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Tiny Whiteflies Provide Insight into Stabilizing Manmade Drones during Takeoff
4/5/2017

The insects spread their wings only after leaping, rotating and reversing direction in midair, TAU researchers say

When whiteflies take off, they don't just spread their wings and fly. Just .03 of an inch long, these tiny insects possess a variety of sophisticated techniques that provide them with exceptional stability in the air. Tel Aviv University researchers now say that they may hold the secret to stabilizing the take-off of small robotic manmade flyers such as miniaturized drones.

TAU research presented at a recent Israel Academy of Sciences and Humanities conference explores how whiteflies, which belong to the order of insects called Hemiptera, successfully take off without flapping their wings, which are 28% longer than their bodies. They raise only their wingtips to provide air resistance and stabilize. The presentation was based on new research following an earlier study published by the Journal of Experimental Biology.

"Whiteflies take a powerful 'jump' before they start using their wings in flight," said Dr. Gal Ribak of TAU's Department of Zoology, who led the research. "Then, when the insects are moving through the air, they have to stop the rotation of their bodies to reorient themselves for flapping flight. They are able to do that by extending the tips of their folded wings, causing high air resistance behind the body. This aerodynamic force stabilizes the take-off and only then do the insects spread their wings and start flying.

"What is noteworthy here is the response time," Dr. Ribak said. "All this takes less than 12 milliseconds, and it doesn't require feedback from the nervous system. Nature is providing us with guidance on how to stabilize the take-off of small robotic manmade flyers."

Small but powerful

According to the study, conducted with TAU undergraduate student Eyal Dafni and in collaboration with the late Prof. Dan Gerling, TAU Emeritus Professor of Entomology, size is a key component of the insects' successful ascent. Their tiny size allows them to execute swift stabilizing responses using the air resistance of different body parts.

"The whiteflies leave the ground rotating forward," said Dr. Ribak. "That rotation should result in the insects somersaulting upon leaving the ground. But the tips of the folded wings provide adequate air resistance, similar to the horizontal surfaces on an airplane tail."

As part of the study, the team filmed the ascent of the insects with high-speed cameras, which allowed them to observe the take-offs in slow motion and extract 3D data on the motion of the insects. (Video) They then used the data to model the aerodynamics and rotation of the insects during take-off. The model revealed the tips of the folded wings to be the most important element of the stability mechanism.

"To test this prediction, we clipped the wingtips of some whiteflies and observed their take-off again," said Dr. Ribak. "As we predicted, the whiteflies with clipped wings were incapable of stabilizing before spreading and flapping their wings."

The researchers are currently studying other small insects with shorter wings that also leap during take-off but use alternative mechanisms for stabilizing the jump.

Photo: Video still of a whitefly "leaping" before beginning to fly. Credit: Laboratory of Dr. Gal Ribak.

Bat Calls Contain Wealth of Discernible Information
12/27/2016

Analyzing some 15,000 bat vocalizations, TAU researchers identify speakers, objectives and contexts of bat conversations

Bats, like humans, are extremely social mammals. They enjoy an average lifespan of 20-30 years, settle in large colonies, and rely heavily on social interactions for their survival, using vocalizations — or calls — for communication. There is very little known about the purpose and content of these noises.

A new Tel Aviv University study published in Scientific Reports extracts critical information from bat vocalizations to offer a rare, informative look into the world of bat communication. The new research, led by Prof. Yossi Yovel of the Department of Zoology at TAU's Faculty of Life Sciences, delves into the veritable cacophony emitted by bats to identify concrete evidence of a socially sophisticated species that learns communication, rather than being born with a fixed set of communication skills.

"When you enter a bat cave, you hear a lot of 'gibberish,' a cacophony of aggressive bat noise – but is this merely 'shouting' or is there information amid the noise?" said Prof. Yovel. "Previous research presumed that most bat communication was based on screaming and shouting. We wanted to know how much information was actually conveyed — and we wanted to see if we could, in fact, extract that information."

For the purpose of the research, Mor Taub and Yosef Prat, students in Prof. Yovel's lab, recorded the sounds emitted by 22 Egyptian fruit bats in TAU's "bat cave" over the course of 75 days. The authors then assembled a dataset of approximately 15,000 vocalizations, which represented the full vocal repertoire the bats used during the experiment. By analyzing this dataset, the authors found that the vocalizations contained information about the identity of the bat emitting the call and even about the identity of the bat being addressed by the call. Moreover, while most of this species' vocalizations were emitted during aggressive encounters, by analyzing the spectral composition of the calls, the authors were also able to distinguish their specific aggressive context (such as squabbling over food, sleeping spots or other resources).

"Studying how much information is conveyed in animal communication is important if you're interested in the evolution of human language," said Prof. Yovel. "Specifically, one big unknown in the world of animal communication is their grasp on semanticity — i.e., when you hear the word 'apple' you immediately imagine a round, red fruit. We found, in our research, that bat calls contain information about the identities of the caller and the addressee, which implies that there is a recognition factor. We were also able to discern the purpose and the context of the conversation, as well as the possible outcome of the 'discussion.'"

Due to the difficulty of cataloguing animal calls, these vocalizations are often grouped into one category in acoustic studies. According to Prof. Yovel, the new findings suggest that delving into animal calls could serve a bigger purpose, shedding light on the evolution of communication altogether.

"We generated a massive amount of data — dozens of calls over three months," said Prof. Yovel. "We have found that bats fight over sleeping positions, over mating, over food or just for the sake of fighting. To our surprise, we were able to differentiate between all of these contexts in complete darkness, and we are confident bats themselves are able to identify even more information and with greater accuracy — they are, after all, an extremely social species that live with the same neighbors for dozens of years."

The researchers were even able to identify different intonations indicating the greetings of a "friend" or a "foe."

"The last finding allowed us to predict whether the two would stay together or part, whether the interaction would end well or badly," said Prof. Yovel, who is currently researching different bat accents and the assimilation of bats into different social groups.

Genetic Testing Proves Bene Israel Community in India Has Jewish Roots
5/10/2016

TAU–Cornell collaboration provides insight into unique community whose history is largely unknown

A new study from Tel Aviv University, Cornell University and the Albert Einstein College of Medicine reveals genetic proof of the Jewish roots of the Bene Israel community in the western part of India. They have always considered themselves Jewish.

"Almost nothing is known about the Bene Israel community before the 18th century, when Cochin Jews and later Christian missionaries first came into contact with it," says first author Yedael Waldman of both TAU's Department of Molecular Microbiology and Cornell's Department of Biological Statistics and Computational Biology. "Beyond vague oral history and speculations, there has been no independent support for Bene Israel claims of Jewish ancestry, claims that have remained shrouded in legend."

"Human genetics now has the potential to not only improve human health but also help us understand human history," says Prof. Eran Halperin of TAU's Department of Molecular Microbiology and Biotechnology and TAU's Blavatnik School of Computer Sciences, who together with Prof. Alon Keinan of Cornell University's Department of Biological Statistics and Computational Biology advised Waldman. The research was published in PLoS One on March 24, 2016.

From folklore to science

According to their oral history, the Bene Israel people descended from 14 Jewish survivors of a shipwreck on India's Konkan shore. The exact timing of this event and the origin and identity of the Jewish visitors are unknown. Some date the event to around 2,000 years ago. Others estimate that it took place in 175 BCE. Still others believe their Jewish ancestors arrived as early as the 8th century BCE.

"In the last few decades, genetic information has become an important source for the study of human history," says Prof. Keinan, the study's senior author. "It has been applied several times to the study of Jewish populations across diasporas, providing evidence of a shared ancestry."

The research team, including members of Prof. Keinan's lab, Prof. Eitan Friedman of TAU's Sackler School of Medicine, and Prof. Gil Azmon and colleagues at Albert Einstein College of Medicine and the University of Haifa, based their study on data from the Jewish HapMap project, an international effort led by Prof. Harry Ostrer of Albert Einstein College of Medicine, to determine the genetic history of worldwide Jewish diasporas. They used sophisticated genetic tools to conduct comprehensive genome-wide analyses on the genetic markers of 18 Bene Israel individuals.

"We found that while Bene Israel individuals genetically resemble local Indian populations, they constitute a clearly separated and unique population in India," Waldman says.

How the community grew

"The results point to Bene Israel being an 'admixed' population, with both Jewish and Indian ancestry. The genetic contribution of each of these ancestral populations is substantial," adds study co-lead author Arjun Biddanda of Cornell.

The results even indicate when the Jewish and Indian ancestors of Bene Israel "admixed": some 19-33 generations (approximately 650-1,050 years) ago.

"We believe that the first encounter involved Middle-Eastern Jews and was followed by a high rate of tribal intermarriage," says Waldman. "This study provides a new example of how genetic analysis can be a valuable and powerful tool to advance our knowledge of human history."

How Bats Recognize Their Own "Bat Signals"
1/28/2016

TAU researcher discovers a unique mechanism bats use to overcome communication interference in the wild

Individual bats emit sonar calls in the dark, using the echo of their signature sounds to identify and target potential prey. But because they travel in large groups, their signals often "jam" each other, a problem resembling extreme radar interference. How do bats overcome this "cocktail party" cacophony to feed and survive in the wild?

A new Tel Aviv University study published in Proceedings of the Royal Society B: Biological Sciences identifies the mechanism that allows individual bats to stand out from the crowd. The research, by Dr. Yossi Yovel of TAU's Department of Zoology, finds that individual bats manage to avoid noise overlap by increasing the volume, duration and repetition rate of their signals.

According to Dr. Yovel, unlocking the mystery of bat echo recognition may offer a valuable insight into military and civilian radar systems, which are vulnerable to electronic interference.

Cocktail party chatter

"Imagine you are at a cocktail party where everyone is uttering the same word over and over again, and you are expected to recognize the echo of your own utterance to identify the location of the punch bowl," Dr. Yovel said. "Now imagine that this is tantamount to your survival. This is the bat experience. Bats often fly in groups and rely on sounds — very similar sounds — to find their food. They deal with two challenges: They need to detect weak echoes in a cluster of noise, and if they manage to receive the echo, they need to recognize it as their own."

Dr. Yovel and his team of TAU researchers, including Eran Amichai and Dr. Gaddi Blumrosen, tested bat responses in situations mimicking a high density of bats. They played back bat echolocation calls from multiple speakers to jam the echoes of five flying Pipistrellus kuhlii bats, simulating a naturally occurring situation of many bats flying in proximity. Under severe interference, bats emitted calls of higher intensity and longer duration, and called more often — but they did not change the pitch of their signals, as was previously believed.

The new study builds on previous research conducted by Dr. Yovel in which he developed miniature microphones, attached to bat backs, allowing for the first-ever recording of bat frequencies in real time.

"In a study we conducted last year, we found evidence that bats do not harness any such 'jamming avoidance,' as hypothesized in the past by other scientists," said Dr. Yovel. He believes that they simply recognize their own voices.

"In another paper, published in 2009, we trained bats to crawl toward one side or another, in the direction of another bat," Dr. Yovel explained. "This indicated that they indeed differentiated between the voice of one bat and another. This also proved they could identify their own calls.

"In the current study, we trained bats to fly around a small room and land on a small object – in the midst of a loud mixture of bat signals playing overhead. They found the object by increasing their emissions: crying louder and longer and shouting more frequently. They cried 'ahhhhhhh' instead of 'ah' twice as frequently — every 50 milliseconds instead of the usual 100 milliseconds."

From bats to automobiles

According to Dr. Yovel, this research may provide insight into engineering used for human beings.

"We want to understand the problem," said Dr. Yovel. "The better we understand the radar interference problem, the easier it will be to solve. In the future, we will all have radar systems in our cars, and there can be hundreds of these on a stretch of highway as well. Individuality must be built into these radar codes, very clear signature codes."

Dr. Yovel is currently seeking how individuality is intrinsic to bat codes, which continues to escape scientific research.

TAU Discovers Genetic Trigger for Asexual Plant Reproduction
1/25/2016

Collaboration with Freiburg University reveals regulator that produces moss embryos without cross-fertilization

The reproduction process is essentially the same in humans, animals and most plants. Both female and male organisms are required to contribute to the phenomenon.

A new joint Tel Aviv University–Freiburg University study offers an alternative: the discovery of a genetic trigger for the development of offspring without cross-fertilization — in moss. It identifies and explores the master genetic switch for self-reproduction in the moss Physcomitrella patens. According to the new study, the BELL1 gene triggers a pathway of genes that facilitate embryo development without fertilization to form fully functional adult moss plants.

The research was led jointly by Prof. Nir Ohad, Director of the Manna Center Program for Food Safety and Security at TAU's Faculty of Life Sciences, and Prof. Ralf Reski of the University of Freiburg. It was recently published in Nature Plants.

"The knowledge gained from our research may help to modernize agriculture, allowing us to clone certain important plants and distribute their seeds to farmers," Prof. Ohad said.

A model for self-fertilization

"Moss possesses both egg cells and motile sperm, and as such, serves as a simple model plant to understand self-fertilization processes," said Prof. Ohad. "Our results explain at the molecular level how asexual reproduction — known as parthenogenesis or apomixes — has evolved. In these processes, genetically identical plants are formed."

In reproduction, a network of genes is activated after the fusion of sperm and egg cell. This leads to the development of an embryo, which then grows into a new living being. Until now, it was unclear whether a central genetic switch for this process existed.

The team pinpoints the gene BELL1 as the master regulator for the formation of embryos and their development in moss. "This gene was conserved in evolution," said Prof. Ohad, a specialist in the epigenetic regulation of reproductive development. He helped identify the first BELL genes in seed plants 20 years ago as a member of a team led by Prof. Robert Fischer of UC Berkeley. "Our new findings may have implications for generating genetically identical offspring from high yielding crop plants."

The scientists harnessed genetic engineering to activate the BELL1 gene in moss plants and observed embryos developing spontaneously on a specific cell type. To their surprise, these embryos grew to fully functional moss sporophytes. These spore capsules later formed spores, which grew into new adult moss plants.

From plants to humans?

According to the study, the protein encoded by the BELL1 gene belongs to the class of "homeobox" transcription factors. Similar homeotic genes are also present in humans and animals, where they also control pivotal developmental processes. Whether or not a congener of BELL1 is a master regulator of embryo development in humans remains unclear.

"Our results are important beyond mosses," said Prof. Reski. "First, they can explain how algae developed into land plants and shaped our current ecosystems. Second, they may help to revive the concept of genetic master regulators in the development of plants, animals and humans."

The study was supported by the German-Israeli Foundation, the Freiburg Excellence Cluster BIOSS and the Freiburg Institute for Advanced Studies. The scientists are carrying forward their research to identify the exact genes triggered by BELL1 to facilitate the formation of embryos without fertilization.

Bat Signals: TAU’s Yossi Yovel Is Cracking Bat Codes
11/24/2015

AFTAU's "Giving Tuesday" campaign invites you to "Adopt-a-Bat" to support scientific research

Photo: Dr. Yossi Yovel and friendDr. Yossi Yovel, the noted biologist and physicist, has established one of the world's foremost labs for the study of bats in the heart of the Tel Aviv University Research Zoo (TAURZ). "In everything I do, and everything I study, I am trying to understand one thing: How animals make decisions in the real world — not in the lab, not in unnatural conditions, but outside, in nature," said Dr. Yovel, who maintains his own batcave of 60 bats on the TAU campus.

And according to Dr. Yovel, Israel's "Batman," insight into bats provides insight into other mammals, humans included. "We want to understand what bats say to each other, how they navigate over hundreds of kilometers, and what they think," he explained. "This is all part of our attempt to understand where our own behavior comes from, what we share with each other and with other animals, and how all this has changed over time."

Now nature enthusiasts will have a fun way to support this important research with the "Adopt-a-Bat" campaign from American Friends of Tel Aviv University, scheduled to launch on Giving Tuesday, December 1, 2015. Everyone from six to 60 will have the opportunity to "adopt" one of Dr. Yovel's little critters and even offer them for unique holiday "gifts." The Web site at http://www.aftau.org/adopt-a-bat will feature photos, fascinating bat facts, and short "biographies" of the bats, as well as a live feed from Dr. Yovel's own batcave. The campaign will continue through December 31.

How to track a bat

In the course of Dr. Yovel's doctoral research, he realized that all existing research on animal behavior had been conducted exclusively in laboratories due to the challenges of monitoring an animal outdoors over long periods of time and over large distances.

"It's not enough to follow an animal in a controlled environment," said Dr. Yovel. "You have to monitor its behavior in the wild. Is it interacting with other animals? Did it find food?" Seeking answers to these questions, he developed state-of-the-art miniature tracking devices that can be attached to a bat's back to track his/her movement and behavior over hundreds, if not thousands, of miles.

"Over the past four years, my lab has developed miniature devices, the smallest in the world, with GPS, audio, video, acceleration, EEG, and other technologies to measure physical and environmental cues that truly allow us to sense the world from a bat's point of view," said Dr. Yovel.

"Our bats are under our constant surveillance. We have been able to discover what a bat is doing even when it's flying more than 3,000 feet above the ground."

More than 1,200 species of bats account for more than 20 percent of all mammals. These miniature flying mammals are highly sociable and emit special sonar signals to sense their environment. "By recording these sounds in real time, we can tell when they're attacking prey or when they encounter another bat and how they respond to it," said Dr. Yovel. "This allows us to reveal how bats work and thrive in a group, which provides radical new insight into the social world of mammals."

City of bats

Bat colonies, or "bat cities," are inhabited by thousands of bats who live together for up to 40 years.

"The largest non-human mammalian cities on earth are bat cities — colonies of millions of bats, all of whom roost together, interact with each other, communicate vocally, fly together, and search for food together," said Dr. Yovel. "We still don't know much about their social systems. We don't know if they live in pairs or in small groups or in families — all of this is still completely unknown. We really want to understand if they transfer information the way humans do.

"We are constantly improving our technology," Dr. Yovel continued. "We are currently working on a device that will also include a camera that will allow us to see what bats see.

"We are also developing a device with electrodes that can be placed on a bat's head to record its brain activity, even while flying. We are constantly working to improve the devices we already invented, to gain even more insight into the world of bats."

TAU Discovery May Redefine Traditional Classifications in the Animal Kingdom
11/18/2015

Research finds a close cousin of the jellyfish evolved into a microscopic parasite that lives in fish

Children are taught that all living organisms — from animals, plants, and fungi to bacteria and single-celled organisms — belong to specifically different categories of organic life. A new discovery by Tel Aviv University researchers and international collaborators is poised to redefine the very criteria used to define and classify these animals.

Researchers have found that a close cousin of the jellyfish has evolved over time into a microscopic parasite. The finding represents the first case of extreme evolutionary degeneration of an animal body.

The research was led by Prof. Dorothée Huchon of TAU's Department of Zoology and Prof. Paulyn Cartwright of the University of Kansas, in collaboration with Prof. Arik Diamant of Israel's National Center for Mariculture and Prof. Hervé Philippe of the Centre for Biodiversity Theory and Modelling, CNRS, France. It was published this week in the Proceedings of the National Academy of Scientists.

What makes a myxozoan

The international research used genome sequencing to find that myxozoans, a diverse group of microscopic parasites that infect invertebrate and vertebrate hosts, are actually are highly degenerated cnidarians — the category or phylum that includes jellyfish, corals and sea anemones.

"These micro-jellyfish expand our basic understanding of what makes up an animal," said Prof. Huchon. "What's more, the confirmation that myxozoans are cnidarians demands the re-classification of myxozoa into the phylum cnidaria."

Despite the radical changes in its body structure and genome over millions of years, the myxozoa have retained some of the basic characteristics of the jellyfish, including the essential genes to produce the jellyfish stinger.

"The myxozoa are microscopic — only a few cells measuring 10 to 20 microns across — and therefore biologists assumed that they were single-celled organisms," said Prof. Huchon. "But when we sequenced their DNA, we discovered the genome of an extremely strange macroscopic marine animal."

Real-world applications

The discovery of the dramatic change from macroscopic marine animal to microscopic parasite is interesting on its own, but it may also have commercial applications, as myxozoa commonly plague commercial fish stock such as trout and salmon.

"Some myxozoa cause a neurological problem in salmon called 'whirling disease,'" said Prof. Huchon. "These fish parasites cause tremendous damage to the fish industry, and unfortunately there is no general treatment against them. We hope that our data will lead to a better understanding of the biology of these organisms and the development of more effective drugs to fight against myxozoa."

The researchers are currently studying the evolution in myxozoa of genes that form the stinging organ of jellyfish. The study was funded by the National Science Foundation, the Binational Science Foundation, and the Israel Science Foundation.

Survival of the Gutless? Filter-Feeders Eject Internal Organs in Response to Stress
6/23/2015

TAU researcher discovers tropical organisms that expel their digestive tracts and rebuild them in 12 days


Arrows point to the areas of new tissue formation five days post-evisceration. Photo: Dr. Noa Shenkar

The vast range of regenerative powers within the animal kingdom has fascinated scientists since the early 18th century. From hydras to planarians and geckos, the remarkable ability of certain species to regrow parts of their bodies and subsequently regain some or all of their original form and function has presented invaluable opportunities for research on human cell signalling, development, and adaptation.

A recent Tel Aviv University study published in Scientific Reports explores the ability of the tropical ascidian Polycarpa mytiligera, a common coral reef organism, to eviscerate and regenerate its gut within 12 days and rebuild its filtration organ, the branchial sac, within 19 days. Dr. Noa Shenkar and her student Tal Gordon from the Department of Zoology at TAU's Faculty of Life Sciences and the Steinhardt Museum of Natural History and National Research Center observed a recurrent pattern of evisceration, "death," and finally rejuvenation in ascidians from the Gulf of Aqaba.

The organism is a "filter-feeder" that eats by straining suspended matter and food particles from water, usually by passing the water over a specialized filtering structure.

Playing dead

"Polycarpa are the most abundant ascidian species in the Gulf of Aqaba and one of the most abundant in the world," said Dr. Shenkar. "In the process of studying their distribution and depths, we noticed they would throw something at us and then immediately shrink and remain highly contracted and camouflaged. I was sure they had died, but something told me not to discard them.

"Sure enough, four days later, the organisms regained their composition — as if they had been 'reborn,'" Dr. Shenkar said. "This was very unexpected."

The researchers conducted most of their study underwater, marking individual organisms then taking movies of the process. They observed the specimens to discover how the viscera were ejected (i.e., from which end of the organism); whether they survived following evisceration; and if and how they rebuilt their organs. They found that the polycarpa ruptured its branchial sac to eject its digestive tract. Using light mechanical pressure, it contracted, camouflaging itself as "dead." See video footage of the contraction: https://www.youtube.com/watch?v=BkuYoSTRWZQ

"In the underwater observatory, we observed fish — which had not fed for a day — circling, but none of them ate the ejected digestive tract," said Dr. Shenkar. Although the eviscerated guts were unpalatable to preying triggerfish and pufferfish, the researchers' chemical analysis revealed no significant levels of toxic compounds in the expelled organs. It is possible that the digestive tract contains other compounds that are unpalatable to the fish, which are not detected in a regular chemical analysis.

A new direction for soft-tissue regeneration research

The polycarpa's evisceration response provides a unique opportunity to deepen the knowledge and revive the study of evisceration in ascidians. But perhaps more importantly, the study findings establish a solid platform from which to study regeneration of the human digestive tract in its molecular, cellular, and developmental aspects.

"All signs point to evisceration as a defense mechanism, and this alone is interesting," said Dr. Shenkar. "But this is also important and relevant to human research. Ascidians and vertebrates — and humans are vertebrates — share close affinities, so understanding ascidian regeneration pathways can point to promising new directions in human soft tissue regeneration research."

The human body and the ascidian body share many basic biochemical and cellular processes as they are both chordates. Studying Polycarpa as a model organism provides insight into the workings of other organisms, as well as an in-vivo model for research of the human immune system and regeneration.

"This information can surely be used to study different biochemical pathways involved in soft-tissue regeneration," Dr. Shenkar concluded.

Bat Species Is First Mammal Found Hibernating at Constant Warm Temperatures
3/10/2015

TAU research changes the concept of hibernation

Many mammals — and some birds — escape the winter by hibernating for three to nine months. This period of dormancy permits species which would otherwise perish from the cold and scarce food to survive to see another spring. The Middle East, with temperate winters, was until recently considered an unlikely host for hibernating mammals.

New research published in Proceedings of the Royal Society of London by Tel Aviv University researchers is set to not only correct this fallacy but also change the very concept of hibernation. Prof. Noga Kronfeld-Schor, Chair of the Department of Zoology at TAU's Faculty of Life Sciences, and doctoral student Dr. Eran Levin found two species of the mouse-tailed bat (the Rhinopoma microphyllum and the R. Cystops) hibernating at the unusually warm and constant temperature of 68°F in caves in Israel's Great Rift Valley. From October to February, these bats were discovered semi-conscious, breathing only once every 15-30 minutes, with extremely low energy expenditures.

"Hibernation in mammals is known to occur at much lower temperatures, allowing the animal to undergo many physiological changes, including decreased heart rate and body temperature," said Prof. Kronfeld-Schor. "But we have found these bats maintain a high body temperature while lowering energy expenditure levels drastically. We hypothesize that these caves, which feature a constant high temperature during winter, enable these subtropical species to survive on the northernmost edge of their world distribution."

Taking their temperature

The researchers monitored the activity of the bats during this period and found that they neither fed nor drank, even on warm nights when other bat species were active in the same caves. The researchers used heat-sensitive transmitters to measure the bats' skin temperature in the caves. Then in the laboratory, they measured the bats' metabolic rates and evaporative water loss at different ambient temperatures.

The bats' average skin temperature in the caves was found to be about 71.6°F. Both bat species reached their lowest metabolic rates at cave temperatures (about 68°F). During hibernation, the bats also exhibited long periods of suspended exhalation.

"Until recently, it was believed that there was no mammalian hibernation in Israel, apart from hedgehogs," said Prof. Kronfeld-Schor. "But this discovery leads us to believe there may be others we don't know about. Scientists haven't been looking for incidences of hibernation at warm temperatures. This is a new direction for us.

"The second main finding is that hibernating animals don't need to lower their body temperatures in order to lower their energy expenditure. These bats exhibited dramatic metabolic depression at warm body temperatures in the hottest caves in the desert."

The researchers found that the bats, like camels, flare their nostrils to conserve water. A month before hibernating, they also changed their diets from unsaturated to saturated fats, feeding only on queen ants with wings to gain a 50 percent increase in body mass.

The researchers are further exploring the importance of heated caves for the conservation of these species.

Leader of the Pack
2/17/2015

TAU study follows the rise of individuals with the greatest influence on collective group behavior

Who takes charge during a disaster or at an accident scene? The question has intrigued sociologists since Gustave Le Bon first studied "herd behavior" in nineteenth-century France. The question of an individual's influence over the activity of a collective has perplexed researchers, in countless studies of this behavior, ever since.

Now a new Tel Aviv University study, published in Behavioral Processes, looks to the animal kingdom to track the rise of group leaders in chaotic situations and pinpoint the traits that set them apart from their followers. The research, led by Prof. David Eilam of the Department of Zoology at TAU's Faculty of Life Sciences and conducted by TAU doctoral students Michal Kleiman and Sivan Bodek, was based on experiments with voles and owls, and its conclusions may reflect on human behavior as well.

"The big controversy remains: Are group behaviors self-organized? Do they emerge spontaneously or under the guidance of a leader?" said Prof. Eilam. "The problem in studying this phenomenon among humans is the ethical consideration. One must limit the research to simulations or to after-the-fact analyses of real situations. On the other hand, collective behavior as a subject is flourishing in animal studies."

An attack from the skies

The researchers sought to establish the differential division of labor in groups by placing several small rodents called voles in a simulated life-threatening situation — an "attack" by predatory barn owls. The owls had no way of physically reaching the rodents, which were always protected by a cage barrier, but their menacing presence sparked pandemonium within the cage. Out of the chaos, the researchers discovered, vole leaders emerged.

"Our study bucks against the notion that leaders arise spontaneously," said Prof. Eilam. "There are always certain individuals who simply contribute more than others — but who they are and what traits make them leaders are the questions we've managed to answer in a limited realm."

The researchers found that, after an owl attack, larger voles calmed more quickly and smaller voles displayed greater anxiety at first, but over time the larger, older male voles assumed leadership and presented an exemplary model for the smaller male voles and female voles. As a consequence of their larger size, experience, and physical strength, the large male voles displayed more consistent behavior to their companions, hardly changing after the owl attack. The smaller male and female voles displayed an extreme range of frightened behavior before the attack, but converged to the mid-range response of the larger males afterwards. The researchers concluded that the larger male voles were less affected by the threat and set an example for the smaller group.

To protect and stabilize

"Less affected by the owl attacks, the experienced, larger male voles set the behavioral code, leading the other voles to imitate their behavior," said Prof. Eilam. "These 'leaders' have a dual role, not just to protect but also to stabilize the behavior of the group. You can also see such leaders emerge in human societies in distress — take post-9/11 New York City, for example, or even among a family in mourning. All differences are set aside and a typical behavioral code under threat emerges, with a few dominant figures at the head."

The behavioral results were further supported by a series of stress hormone tests before and after the simulated owl attacks, revealing that the smaller voles had high corticosterone levels, while the levels in the larger voles remained stable.

Prof. Eilam is currently extending the study to larger groups to obtain a better representation of the way swarms, flocks, or crowds organize behavior. "We are also trying to uncover what the 'leaders' benefit from their costly role in the group, and how information is passed on from one group to the next," he said.

Make Like a Squid and Transform
2/12/2015

TAU researcher discovers that squid recode their genetic make-up on-the-fly to adjust to their surroundings

The principle of adaptation — the gradual modification of a species' structures and features — is one of the pillars of evolution. While there exists ample evidence to support the slow, ongoing process that alters the genetic makeup of a species, scientists could only suspect that there were also organisms capable of transforming themselves ad hoc to adjust to changing conditions.

Now a new study published in eLife by Dr. Eli Eisenberg of Tel Aviv University's Department of Physics and Sagol School of Neuroscience, in collaboration with Dr. Joshua J. Rosenthal of the University of Puerto Rico, showcases the first example of an animal editing its own genetic makeup on-the-fly to modify most of its proteins, enabling adjustments to its immediate surroundings. The research, conducted in part by TAU graduate student Shahar Alon, explored RNA editing in the Doryteuthis pealieii squid.

"We have demonstrated that RNA editing is a major player in genetic information processing rather than an exception to the rule," said Dr. Eisenberg. "By showing that the squid's RNA-editing dramatically reshaped its entire proteome — the entire set of proteins expressed by a genome, cell, tissue, or organism at a certain time — we proved that an organism’s self-editing of mRNA is a critical evolutionary and adaptive force." This demonstration, he said, may have implications for human diseases as well.

Using the genetic red pencil

RNA is a copy of the genetic code that is translated into protein. But the RNA "transcript" can be edited before being translated into protein, paving the way for different versions of proteins. Abnormal RNA editing in humans has been observed in patients with neurological diseases. The changing physiological appearance of squid and octopuses over their lifetime and across different habitats has suggested extensive recoding might occur in these species. However, this could never be confirmed, as their genomes (and those of most species) have never been sequenced.

For the purpose of the new study, the researchers extracted both DNA and RNA from squid. Harnessing DNA sequencing and computational analyses at TAU, the team compared the RNA and DNA sequences to observe differences. The sequences in which the RNA and DNA did not match up were identified as "edited."

"It was astonishing to find that 60 percent of the squid RNA transcripts were edited. The fruit fly, for the sake of comparison, is thought to edit only 3% of its makeup," said Dr. Eisenberg. "Why do squid edit to such an extent? One theory is that they have an extremely complex nervous system, exhibiting behavioral sophistication unusual for invertebrates. They may also utilize this mechanism to respond to changing temperatures and other environmental parameters."

"Misfolding" the proteins

The researchers hope to use this approach to identify recoding sites in other organisms whose genomes have not been sequenced.

"We would like to understand better how prevalent this phenomenon is in the animal world. How is it regulated? How is it exploited to confer adaptability?" said Dr. Eisenberg. "There may be implications for us as well. Human diseases are often the result of 'misfolded' proteins, which often become toxic. Therefore the question of treating the misfolded proteins, likely to be generated by such an extensive recoding as exhibited in the squid cells, is very important for future therapeutic approaches. Does the squid have some mechanism we can learn from?"

The researchers recently received an Israel-U.S. Binational Science Foundation grant to explore the subject of genetic editing in octopuses.

I'll Have the (Test-Tube) Chicken
2/4/2015

TAU researcher launches world's first feasibility study on meat cultured in a lab

Concrete buildings, clean drinking water, and antibiotics are just a few of the "unnatural" benefits of modernity. Now cultured meat engineered in a laboratory, also known as in-vitro meat, may be poised to join this estimable list.

Tel Aviv University, together with the Modern Agricultural Foundation, has just launched a trailblazing feasibility study on cultured chicken breast production. The study will determine, among other things, how cultured meat, grown in a lab from animal stem cells, could be manufactured commercially, and examine the costs, technology, and potential problems involved. Prof. Amit Gefen of TAU's Department of Biomedical Engineering, one of the world's leading experts in tissue engineering, is leading the study on cultured meat production.

Cultured meat is produced by placing stem cells in a growth culture (fetal bovine serum, for example, is extracted from cow uteruses and rich with energy substrates, amino acids, and inorganic salts that support cell metabolism and growth). The cells divide and grow, creating solid pieces of meat.

There are many reasons to prefer cultured meat, researchers advise. First, the real thing isn't exactly "real" anymore. Animals raised for eventual slaughter are shot full of growth hormones and antibiotics, which are later ingested by people. Animal cruelty, which offends the values of many cultures, is another important reason, not to mention that health and safety regulations are often overlooked in factories.

But even if meat could be produced humanely, naturally, and safely, the world is fast approaching its production limit. By 2050, the world's population is projected to reach 9.2 billion, and meat production will need to be at least double what it is today, say experts.

For more, read the story in the Times of Israel: "'Test-tube steak' could be coming to your plate soon"

Sending Bat Signals: Unique “Supper's Ready” Alert Beckons Hungry Bats
1/22/2015

TAU researcher discovers bat homing call informs other bats of enticing prey several hundred feet away

The sound of a bag of potato chips being torn open cuts through a darkened movie theater. The noise, in an otherwise silent space, pinpoints for all moviegoers exactly where the chips are being devoured. According to a new Tel Aviv University study, bats operate in a similar fashion.

Bats, hunting at night in groups, improve their chances of finding the best patches of insects by engaging in reciprocal eavesdropping, says the study's lead investigator Dr. Yossi Yovel of TAU's Department of Zoology. "Bats emit sonar signals to sense their environment. By recording them in real time, we can tell when they're attacking prey or when they encounter another bat and how they respond to it. This reveals new knowledge on the world of these miniature flying mammals, which account for more than 20% of mammalian species. It is an example of how an animal gains from working in a group, and it could even provide insight into operating swarms of drones in a collective search mission, for example."

The research, published recently in the journal Current Biology, was conducted in part by TAU graduate students Noam Cvikel, Katya Egert-Berg, and post-doc Eran Levin.

Watch a New York Times video report about this research

Eavesdropping on the eavesdroppers

The subject of the study, the Rhinopoma microphyllum, also known as the greater mouse-tailed bat, preys on flying queen ants, an insect that congregates in highly-dispersed patches that can be difficult to find. While bats are able to use biosonar to detect their prey within 33 feet, their remarkable "eavesdropping" honing radar is able to identify other bats eating that prey from some 328 feet away. The study, conducted over two summers (2012-13) in Israel's northern Galilee region, found that bats' unique ability to snoop on others' hunting improved their collective chance of feeding well.

For the purpose of the study, Dr. Yovel and his team rigged 30 greater mouse-tailed bats, a highly social species of bats that migrate to Israel for the summer, with very small, GPS-enabled ultrasonic recorders. The chips were attached with surgical glue which wore off after a week, causing them to fall off the bats. The team collected these chips to analyze the data they contained. They were only able to retrieve 40 per cent of the recorders, but they contained valuable recordings of 1,100 bat interactions, allowing the researchers to identify when the bats were hunting down prey and when they were simply chatting with other bats.

"The high bat density might result in a few possible sources of interference," said Dr. Yovel. "A bat might compete for the same prey, bat signals might theoretically jam others' sonar calls, and bats might suffer because they constantly need to track other bats while at the same time tracking food. We found this last source to be of most importance to the bats. Imagine that you are tracking a fly and a baseball is thrown towards you — you will have to stop tracking the fly. This is a kind of trade-off. Foraging in a group is beneficial, but not when the group is too dense."

Using high-tech to study low-tech animals

"We seek to understand nature," Dr. Yovel said. "We seek to understand how animals make decisions in the wild, but we are very limited in our ability to track animals in their natural environment, to accurately track their behavior, their foraging tactics and interactions with counterparts. In this study we were lucky to be able to harness a novel technology to gain insight into the secret world of bats."

The researchers are continuing to study bat behavior, comparing bats that use different foraging strategies. Dr. Yovel is also developing new sensors to monitor a host of other bat biological markers.

A Bird's-Eye View of the Protein Universe
11/18/2014

TAU study offers first global picture of the evolutionary origins of proteins


Networks of similarity among protein structural domains. The complex protein space features both continuous and discrete regions. Image courtesy Varda Wexler of the multimedia unit of the Faculty of Life Sciences.

Each cell contains thousands of proteins, each one of which bears a unique signature. All proteins, distinct in shape and function, are built from the same amino acid strings. Many proteins are vital, as evidenced by the plethora of diseases linked to their absence or malfunction. But how exactly did proteins first come to be? Do they all share a single common ancestor? Or did proteins evolve from many different origins?

Forming a global picture of the protein universe is crucial to addressing these and other important questions, but it's nearly impossible to do. Such a bird's-eye view demands comparisons of nearly innumerable pairs of known and unknown proteins. Now, new research published in the journal PNAS by Prof. Nir Ben-Tal of the Department of Biochemistry and Molecular Biology at Tel Aviv University's Faculty of Life Sciences, Prof. Rachel Kolodny of University of Haifa's Department of Computer Science, and Dr. Sergey Nepomnyachiy of New York University's Polytechnic Institute, is providing a first step toward piecing together a global picture of the protein universe.

"This is the first study that combines sequence and shape similarity between proteins within the context of networks to provide a bird's eye view of the protein universe," said Prof. Ben-Tal. "The network offers a natural way to organize and search among all proteins. It could be used to theorize about protein evolution, suggest evolutionary pathways, and even suggest strategies for the design of new proteins."

A master of their domain

Conveniently, proteins are comprised of various combinations of domains — conserved and commonly occurring parts that can function on their own; it is therefore sufficient to analyze relationships among these. The researchers studied the evolutionary relationships among a representative set of 9,710 domains. They compared them, searching for common motifs. The motif includes parts of each of the two compared domains, and can therefore indicate an evolutionary relationship among them. The researchers presented their results as a series of networks, in which edges connect domains with a shared motif.

According to their analysis of protein pairs, the researchers revealed a truly complex picture of protein space — a large, connected component with many isolated "islands."

"The protein network can be interpreted as a collection of evolutionary paths in protein space," said Prof. Ben-Tal. "Paths in the major connected component of the network include many domains, and demonstrate the sequence and shape resemblance between them. The large number of paths within the major connected component suggest it is particularly easy to add and delete motifs in the continuous region of protein space without impeding stability. Apparently, evolution took advantage of this property to design new proteins with novel functions."

The researchers are currently working on ways of supplementing the study with data on protein function (such as DNA/RNA binding), its role in disease pathology, and drug binding to individual proteins.

Less Sex + More Greens = A Longer Life
11/17/2014

New TAU study finds a slow pace of life is the secret to longevity of lizards and snakes

Doctors tell us that the frenzied pace of the modern 24-hour lifestyle — in which we struggle to juggle work commitments with the demands of family and daily life — is damaging to our health. But while life in the slow lane may be better, will it be any longer? It will if you’re a reptile.

A new study by Tel Aviv University researchers finds that reduced reproductive rates and a plant-rich diet increases the lifespan of reptiles. The research, published in the journal Global Ecology and Biogeography, was led by Prof. Shai Meiri, Dr. Inon Scharf, and doctoral student Anat Feldman of the Department of Zoology at TAU's Faculty of Life Sciences, in collaboration with Dr. Daniel Pincheira-Donoso of the University of Lincoln, UK, and other scientists from the US, the UK, Ecuador, and Malaysia.

The international team collected literature on 1,014 species of reptiles (including 672 lizards and 336 snakes), a representative sample of the approximately 10,000 known reptiles on the planet, and examined their life history parameters: body size, earliest age at first reproduction, body temperature, reproductive modes, litter or clutch size and frequency, geographic distribution, and diet. The researchers found that, among other factors, early sexual maturation and a higher frequency of laying eggs or giving birth were associated with shortened longevity.

Putting the brakes on physical stress

"There were aspects of this study that we were able to anticipate," said Prof. Meiri. "Reproduction, for example, comes at the price of great stress to the mother. She experience physiological stress, is unable to forage efficiently, and is more vulnerable to her surroundings. This reflects evolutionary logic. To relate this to humans, imagine the physical stress the body of an Olympic gymnast experiences — and the first thing that disappears is her period. In reptiles, it also increases the probability of being preyed upon.

"We found that reptiles that were sexually mature early on were less likely to make it to old age," Prof. Meiri continued. "Live fast and die young, they say — but live slow, live long."

Eat your greens

The team also discovered that herbivores — lizards with a plant-rich diet — lived longer than similar-sized carnivores that ate mostly insects. Ingestion of a protein-rich diet seemed to lead to faster growth, earlier and more intense reproduction, and a shortened lifespan. Herbivorous reptiles were thought to consume nutritionally poorer food, so they reached maturity later — and therefore lived longer.

Hunting may also be riskier than gathering fruits and leaves — at least for animals, the researchers concluded. "If you're an animal, hunting your food can be dangerous," said Prof. Meiri. "You risk injury or even death. This is why you cannot simply transfer this logic to humans. Going to buy a head of lettuce at the supermarket is just as risky as going to the meat department. As a reptile, if you eat plants, you may need to be frugal, take life more slowly, and save your calories for digestion. You are forced to have a slower life, a more phlegmatic existence."

The researchers also found correlates that suggested reptiles in geographically colder regions lived longer — probably due to two factors: hibernation, which offers respite from predators, and slower movement due to a seasonal drop in metabolic rate. "Our main predictors of longevity were herbivorous diets, colder climates, larger body sizes, and infrequent and later reproduction," said Prof. Meiri. "I stress that you cannot simply transfer the results of a study on lizards to humans — but this is the first study of its kind on reptiles, which does open up an avenue for further research on other factors that lead to longevity of these and other species."

The Bad News: Just in Time for Passover, Plague of Locusts Arrives in Israel
8/5/2014

The good news: Swarms present an opportunity for regional collaboration, says TAU researcher

Celebrated as the eighth plague visited on the people of Egypt in the story of Passover, locusts have been pestering farmers for millennia. Common in Sudan and Egypt, now swarms have arrived in Israel, too—just in time for the holiday in which they play a role in the Israelites' escape from slavery.

Though the timing is uncanny, researchers note that the current plague is a normal ecological phenomenon rather than a form of divine punishment. In the Middle East, locusts typically swarm every 10 to 15 years, and the pattern can be unpredictable. In this case, a rainy winter caused excessive vegetation growth—and a boom in the locust population.

Because the swarms impact several countries in the region, Prof. Amir Ayali of Tel Aviv University's Department of Zoology believes this could be an opportunity for collaboration, in much the way birders and ornithologists from Israel, Jordan, and Palestine cooperate in monitoring bird migration. "Maybe scientists should work to bridge the gaps in the region," he says in a recent article in Smithsonian. "We could take the opportunity of this little locust plague to make sure together that we're better prepared for the next."

From a solitary pest to a dangerous plague

A locust begins life as a form of grasshopper. When it switches from a sedentary, solo lifestyle to a swarming lifestyle, it undergoes a series of physical, behavioral, and neurological changes, representing one of the most extreme cases of behavioral plasticity found in nature. Before swarming, locusts change from their normal tan or green coloring to a bright black, yellow, or red exoskeleton. Females begin laying eggs in unison, which hatch in synch and fuel the swarm. In this way, millions of insects can become billions in a matter of months. The swarm will consume any vegetation in its path, and will move to new feeding grounds after devouring everything at hand.

The damage caused by locust swarms is expensive, taking into account the cost of pesticides, crop damage, replacement food provisions and more. And while it's important to develop new methods for dealing with the swarms, the best strategy would be to prevent the swarms from taking flight in the first place through monitoring of locust-prone areas. "We really want to find them before they swarm, as wingless nymphs on the ground," explains Prof. Ayali. "Once you miss that window, your chances of combating them are poor and you're obliged to spray around like crazy and hope you catch them on the ground."

For the full story on this modern-day locust plague, see the smithsonian.com story:
http://blogs.smithsonianmag.com/science/2013/03/a-plague-of-locusts-descends-upon-the-holy-land-just-in-time-for-passover/


The "Memory" of Starvation is in Your Genes
7/31/2014

Israeli and American researchers discover the genetic mechanism that passes on physical responses to hardship

During the winter of 1944, the Nazis blocked food supplies to the western Netherlands, creating a period of widespread famine and devastation. The impact of starvation on expectant mothers produced one of the first known epigenetic "experiments" — changes resulting from external rather than genetic influences — which suggested that the body's physiological responses to hardship could be inherited. The underlying mechanism, however, remained a mystery.

In a paper published recently in the journal Cell, Dr. Oded Rechavi, Dr. Leah Houri-Ze'ev, and Dr. Sarit Anava of Tel Aviv University's Faculty of Life Sciences and Sagol School of Neuroscience, Prof. Oliver Hobert and Dr. Sze Yen Kerk of Columbia University Medical Center and the Howard Hughes Medical Institute, and Dr. Wee Siong Sho Goh and Dr. Gregory J. Hannon of the Cold Spring Harbor Laboratory and the Howard Hughes Medical Institute, explore a genetic mechanism that passes on the body's response to starvation to subsequent generations of worms, with potential implications for humans also exposed to starvation and other physiological challenges, such as anorexia nervosa.

"There are possibly several different genetic mechanisms that enable inheritance of traits in response to changes in the environment. This is a new field, so these mechanisms are only now being discovered," said Dr. Rechavi. "We identified a mechanism called 'small RNA inheritance' that enables worms to pass on the memory of starvation to multiple generations."

Does RNA have a memory?

RNA molecules are produced from DNA templates in response to the needs of specific cells. "Messenger" RNA molecules (mRNAs) contain instructions for the production of proteins, which service cells and allow them to function. But other RNA molecules have different regulatory functions. Small RNAs are one species of these regulatory RNAs — short molecules that regulate gene expression, mostly by shutting genes off, but sometimes by turning them on.

Dr. Rechavi first became interested in studying starvation-induced epigenetic responses following a discovery made as a post doctorate in Prof. Hobert's lab at Columbia University Medical Center in New York. "Back then, we found that small RNAs were inherited, and that this inheritance affected antiviral immunity in worms. It was obvious that this was only the tip of the iceberg," he said.

In the course of the new study, worms (C.elegans nematodes) were starved early in their development. They responded by producing small RNAs, which function by regulating genes through a process that is known as RNA interference (RNAi). The researchers discovered that the starvation-responsive small RNAs target genes that are involved in nutrition. More important, the starvation-induced small RNAs were inherited by at least three subsequent generations of worm specimens.

Inheriting resilience

"We were also surprised to find that the great-grandchildren of the starved worms had an extended life span," said Dr. Rechavi. "To the best of our knowledge, our paper provides the first concrete evidence that it's enough to simply experience a particular environment — in this case, an environment without food — for small RNA inheritance and RNA interference to ensue. In this case, the environmental challenge is starvation, a very physiologically relevant challenge, and it is likely that other environments induce transgenerational inheritance of small RNAs as well.

"We identified genes that are essential for production and for the inheritance of starvation-responsive small RNAs. RNA inheritance could prove to be an important genetic mechanism in other organisms, including humans, acting parallel to DNA. This could possibly allow parents to prepare their progeny for hardships similar to the ones that they experience," Dr. Rechavi said.

The researchers are currently researching a wide variety of traits affected by inherited small RNAs.

Turning the Tide on "Jellyfish Terrorism"
7/16/2014

TAU researcher suggests converting the expansive species into a useful resource

A United Nations report released in May called on scientists worldwide to join a war on jellyfish. Jellyfish have disrupted the marine ecosystem and are seen by scientists as "terrorists" in the food chain. For example, a recent report describes how a bloom of jellyfish, spanning four square miles, devoured 100,000 salmon at a fish farm in Northern Ireland, causing damages of $1.5 million. And even though 450,000 tons of jellyfish are fished every year for the East Asian food industry, jellyfish consumption is far from effective in reducing or controlling the rapidly reproducing creatures’ population growth.

According to a recent article in Haaretz, Tel Aviv University has been successful in turning jellyfish to more useful purposes. Prof. Shahar Richter of TAU's Department of Materials Science and Engineering and Center for Nano Science and Nanotechnology, Prof. Michael Gozin of TAU's School of Chemistry, and TAU students Liron Reshef, Gad Kedem, Roman Nudelman, and Dr. Tamila Giolahamdov have devised a way of turning jellyfish into a resource that could be used in various industries, providing an incentive to fish the creatures en masse and reduce their number.

Richter's method, now being registered as a patent, could turn jellyfish into an attractive resource for paramedical, hygiene, and perishable-product industries. They could be used for environmentally safe medical treatments, advanced bandages, and other plastic products.

The jellyfish's triple threat

"Jellyfish cause damage in three major areas," Richter told Haaretz. "First, they clog up and paralyze atomic or electric power stations and desalination plants. In fact, they spell disaster for any facility that uses sea water. This happens in many places, including Korea, Japan, Sweden and India."

Second, jellyfish have had a dramatic impact on the world fishing industry, snagging and blocking fishing nets with their massive size. The third industry to come under jellyfish attack is tourism. While jellyfish on Israeli shores cause painful burning at worst, the species off Australia's shores are deadly, requiring the closure of beaches for extended periods.

A jellyfish consists of an umbrella-shaped bell and trailing tentacles; 90 percent of it is water. In studies, the researchers first cut off the tentacles and then ground the jellyfish to eliminate the water. The remaining substance consisted of two proteins useful in the biotechnological industries — collagen (found in human skin) and mucin (found in mucous tissues). The team developed methods to turn this jellyfish "essence" into composite materials, adding nanoparticles with useful properties, like electrical conductivity, anti-bacterial materials, medicines, and glowing substances.

"The result is a composite biological material. Our innovation is proving that the material is perishable, so that if we bury it in the ground it will decompose, not pollute or cause environmental damage," Prof. Richter told Haaretz. The team is currently examining industrial and commercial applications for this material.

Read more in Haaretz:
"Israeli scientist turning jellyfish plague into plenty"

Blind Fish Use Their Mouths to "See" in the Dark
5/6/2014

TAU researchers discover eyeless Mexican cavefish use suction to navigate

Blind fish found in the pools of Mexican caves use high-frequency waves generated with their mouths to navigate, Tel Aviv University researchers have discovered.

In a study published last month in the Journal of Experimental Biology, Dr. Roi Holzman and Dr. Shimrit Perkol-Finkel of TAU's School of Zoology and Prof. Gregory Zilman of TAU's School of Mechanical Engineering observed a previously unknown mechanism by which Mexican blind cavefish (Astyanax fasciatus) produce suction waves to create vibrations in the water around them, then measure their distance to nearby objects by detecting changes to water pressure on their skin.

The researchers described the practice as being somewhat similar to echolocation, the method used by bats and dolphins to gauge their distance from objects by emitting sound waves and measuring how long they take to bounce back. But unlike echolocation, the fish's method does not measure time but the ways in which water pressure changes as a result of the suction movement.

The team conducted experiments in which they observed the mouth movements of specimens, noting that the fish made much more frequent movements when around new objects than when swimming in familiar territory. They also noted that the suction action increased dramatically the closer the fish came to solid objects.  

For more, read the Times of Israel story:
http://www.timesofisrael.com/israelis-find-how-eyeless-fish-navigates

A Digital Test for Toxic Genes
1/29/2014

TAU researchers develop a computer algorithm that identifies genes whose activation is lethal to bacteria

Like little factories, cells metabolize raw materials and convert them into chemical compounds. Biotechnologists take advantage of this ability, using microorganisms to produce pharmaceuticals and biofuels. To boost output to an industrial scale and create new types of chemicals, biotechnologists manipulate the microorganisms' natural metabolism, often by "overexpressing" certain genes in the cell. But such metabolic engineering is hampered by the fact that many genes become toxic to the cell when overexpressed.

Now, Allon Wagner, Uri Gophna, and Eytan Ruppin of Tel Aviv University's Blavatnik School of Computer Science and Department of Molecular Microbiology and Biotechnology, along with researchers at the Weizmann Institute of Science, have developed a computer algorithm that predicts which metabolic genes are lethal to cells when overexpressed. The findings, published in Proceedings of the National Academy of Sciences, could help guide metabolic engineering to produce new chemicals in more cost-effective ways.

"In the lab, biotechnologists often determine which genes can be overexpressed using trial and error," said Wagner. "We can save them a lot of time and money by ruling out certain possibilities and highlighting other, more promising ones."

Gaining an EDGE

When metabolic genes are expressed, the genetic information they contain is converted into proteins, which catalyze the chemical reactions necessary for life. Overexpression means that greater-than-normal amounts of proteins are produced. Biotechnologists typically overexpress native genes of an industrial microorganism to boost a certain metabolic pathway in the cell, thus increasing the production of desired compounds. Sometimes they overexpress foreign genes — genes transferred from other organisms — in an industrial microbe to build new metabolic pathways and allow it to synthesize new compounds. But they often find that their efforts are hindered by the toxicity of the genes that they wish to overexpress.

Prof. Ruppin's laboratory builds large-scale software models of cellular metabolism, one of the most fundamental aspects of life. These models convert physical, chemical, and biological information into a set of mathematical equations, allowing scientists to learn how cells work and explore what happens if they are tweaked in certain ways. The newly developed algorithm, Expression Dependent Gene Effects, or EDGE, predicts what happens if scientists manipulate cells to overexpress certain genes. EDGE allows biotechnologists to foresee cases in which the overexpressed genes become toxic and then direct their efforts toward other genes.

To validate their method, TAU researchers used genetic manipulation tools to overexpress 26 different genes in E. coli bacterial cells. Comparing the results of their computer simulations with the actual growth of the overexpressed strains that was measured in the lab, they saw that EDGE was able to predict which of the overexpressed genes turned out to be lethal to E. coli. EDGE was also successful in identifying cases of foreign genes that were toxic to E. coli, as the researchers learned from comparing the simulations' results with data collected by their collaborators at the Weizmann Institute of Science.

Beyond bacteria

EDGE's applications appear to extend beyond bacteria. The researchers conducted tests showing that the genes EDGE predicted to be toxic when overexpressed are expressed at low levels not only in microorganisms like bacteria, but also in multicellular organisms, including humans. The researchers say these results reflect the vital evolutionary need to keep the expression of potentially deleterious genes in check.

"Although EDGE's current focus is biotechnology, gene overexpression also plays a central part in many human diseases, particularly in cancer. We hope that future work will apply EDGE to those directions," Wagner said.

How Bats Took Over the Night
12/12/2013

TAU researchers unlock the secrets of echolocation's relationship to vision

Blessed with the power of echolocation — reflected sound — bats rule the night skies. There are more than 1,000 species of these echolocating night creatures, compared with just 80 species of non-echolocating nocturnal birds. And while it seems that echolocation works together with normal vision to give bats an evolutionary edge, nobody knows exactly how.

Now Dr. Arjan Boonman and Dr. Yossi Yovel of Tel Aviv University's Department of Zoology suggest that bats use vision to keep track of where they're going and echolocation to hunt tiny insects that most nocturnal predators can't see. The findings, published in Frontiers in Physiology, add to our scientific understanding of sensory evolution.

"Imagine driving down the highway: Everything is clear in the distance, but objects are a blur when you pass them," said Dr. Boonman. "Well, echolocation gives bats the unique ability to home in on small objects — mostly insects — while flying at high speeds."

Battle of the senses

Bats do most of their feeding at dusk, when insects are most active and there is still plenty of light. Under these conditions, vision seems a better option than echolocation — it conveys more information, and more quickly, at a higher resolution. The researchers wondered: If bats evolved vision before echolocation, as scientists believe, why did echolocation ever come along?

The team set out to answer this question by comparing the distances at which the two senses can detect small objects. To estimate the range of ultrasonic bat echolocation, the researchers played taped calls of two species of bats in a soundproof room and recorded the way the sound bounced off four dead insects — a moth, an ant, a lacewing, and a mosquito. Vision is hard to simulate, so, extrapolating from the findings of two previous studies, the researchers calculated the distance at which bats would be able to see the same insects in medium to low light.

Even erring on the side of vision in their estimates, the researchers found that echolocation was twice as effective as vision in detecting the insects in medium to low light — from 40 feet away versus the 20 feet that was the effective range with vision. They also note that echolocation is unaffected by objects in the background, while visual range is three-to-five fold worse when it has to contend with obstacles like vegetation. Previous studies have shown that echolocation provides more accurate estimates of the distance and velocity of objects, and sometimes even of the distance of the background behind them.

These results suggest that echolocation gives bats a huge evolutionary advantage, allowing them to track insects from further away and with greater accuracy at peak feeding time. Echolocation also, of course, allows bats to continue hunting into the night, when their competitors are blinded by darkness.

A one-two evolutionary punch

On the negative side, bat echolocation was poor at detecting large objects in the distance: Vision can detect large objects at distances several orders of magnitude greater than echolocation does. The researchers think that bats therefore use both senses in combination — vision mostly for orientation, navigation, and avoiding large objects in the distance, and echolocation to search for small prey. Different species of bats probably combine the senses somewhat differently.

"We believe that bats are constantly integrating two streams of information — one from vision and one from echolocation — to create a single image of the world," said Dr. Yovel, also of TAU's Sagol School of Neuroscience. "This image has a higher definition than the one created by vision alone."

The combination of vision and echolocation opened up a large nocturnal advantage for bats in which they have multiplied and diversified — bats account for 20 percent of all classified mammal species on earth today. The researchers speculate that nocturnal birds may not have evolved their own ultrasonic echolocation for anatomical reasons. The next steps are to research how bats integrate echolocation and vision and what the evolutionary costs of echolocation are.

Shining a Light on the Spooky World of Bats
10/31/2013

TAU researchers equip bats with cutting-edge technology to follow them into the darkness for the first time

Roosting upside-down in caves and flying through the night on leathery wings, bats are dark and mysterious creatures. They are popularly associated with the world of vampires, werewolves, and witches that we celebrate on Halloween.

Now Dr. Yossi Yovel of Tel Aviv University's Department of Zoology is using cutting-edge technology to shine a light on the shadowy behavior of bats. By equipping a colony with super-lightweight video cameras, audio recorders, GPS devices, and brain-monitoring equipment, he hopes to reveal their secrets — with applications for sonar and radar technology and brain science. Faculty and students from the School of Electrical Engineering and School of Mechanical Engineering are contributing to the project.

"My team and I believe bat behavior should be studied in the wild, so we created our own wild colony," says Dr. Yovel. "We will be the first to release bats raised in captivity and to equip them with recording devices. After spending the summer testing the technology, we're getting ready to launch."

Born (in captivity) to be wild

Dr. Yovel and his students have created two bat colonies, each with a few dozen members, on the grounds of TAU's Zoological Gardens. One is made up of bats born in the wild and their pups born in captivity. The other is made up entirely of bats born and raised in captivity. Bats from both colonies have adapted to their indoor roosts and are comfortable associating with the research team, says Dr. Yovel. The ultimate goal is to allow bats raised entirely in captivity to come and go freely – with monitoring equipment attached.

As a test run, Dr. Yovel will release the mixed colony into the wild this winter. Last month, he created a window connecting the colony's roost to a caged outdoor area, which the bats are making use of. The goal is to habituate the bats to coming and going freely. Dr. Yovel made the roost as comfortable as possible and chose to release them in the winter, when the weather is worse and there are fewer bugs to eat, to encourage the bats to return.

"We think there is a very strong chance they will return," he says. "If they don't, we'll try again with the colony born entirely in captivity. Members of that colony have already escaped and come back."

Meanwhile, back in the batcave ...

By monitoring the bats outside the laboratory, Dr. Yovel hopes to learn how they use echolocation to effectively hunt insects and find fruit and how they behave in groups. When the bats leave the roost every night, the GPS devices will track their travels; the cameras will document what they see and hear; the audio recorders will capture their sonar signals; and the EEG devices will monitor the electrical signals in their brains.

The GPS devices have been tested in a previous study, and Dr. Yovel has successfully recorded audio and video on flying bats in the laboratory. He has also recorded the slow brain waves characteristic of sleep in anesthetized bats. Besides leading to more knowledge about bats as a species, the research could have applications in the study of robotics, sensors, and sonar technology, along with the functioning of the brain. In the future, Dr. Yovel may introduce additional technologies, like night vision, and create a website featuring streaming video of the roosts and data about the individual bats.

TAU operates Israel's first and only academic research zoo, one of only two on-campus zoos in the world:
http://www.tau.ac.il/lifesci/zoo/research.html

For more, see the Gizmag story at:
http://www.gizmag.com/bat-gps-microphones/23264/

1.8 Million-Year-Old Skull Sheds New Light on Human Evolution
10/23/2013

TAU researcher says finding is evidence of a simpler evolutionary path for humans

Dr. Yoel Rak of Tel Aviv University's Sackler Faculty of Medicine and an international team of researchers released a study last week based on a 1.8 million-year-old skull that suggests human evolutionary history may be simpler than previously believed. There is wide agreement that the discovery of the skull is a watershed in the study of evolution.

The intact skull — that of a primitive human ancestor — was found in the Republic of Georgia in 2005. Dr. Rak traveled to Georgia in 2011 to carefully separate the skull from surrounding rock and sediment using specialized tools and a microscope. Along with partial remains previously unearthed at the site, the skull gave scientists the earliest-ever glimpse of the physical diversity of a group of pre-humans living at one time.

In a study published last Thursday in Science, the researchers say the remains support the theory that modern human ancestry includes fewer species than previously thought. The remains are different sizes, and if they had been discovered in separate sites, they might have been classified as different species by current standards. But because they were found together, they are assumed to represent members of the same species — either early Homo erectus or its predecessor Homo georgicus.

Measuring evolution with a new yardstick

"The fact that all these fossils were found in a single pit in the ground led us to assume that we are talking about a single species," says Dr. Rak, who teaches anatomy and human evolution and is a member of the prestigious Israel Academy of Sciences and Humanities. "With the considerable range of variation that is apparently exhibited in this confined site, the Georgian fossil population has become a yardstick that helps define a single fossil species."

The remains — the oldest ever found outside of Africa — also push back the date at which pre-humans are believed to have left the continent where they evolved. The skull had a number of notably primitive features: a long, apelike face; large teeth; and a tiny braincase, about one-third the size of that of a modern human being. This constellation of features confirmed that, contrary to previous conjecture, early pre-humans did not need big brains to make their way out of Africa and north to the rest of the world.

For more, see the Times of Israel story:
http://www.timesofisrael.com/tel-aviv-prof-helps-shake-up-evolutionary-tree-with-1-8m-year-old-skull-find/

Bugs Not Gay, Just Confused
10/21/2013

TAU research finds that homosexuality in insects and spiders is a case of mistaken identity

Many species of insects and spiders engage in homosexual behavior, like courting, mounting, and trying to mate with members of the same sex. But it is unclear what role evolution plays in this curious situation. Like heterosexual behavior, it takes time and energy and can be dangerous — and it lacks the potential payoff of procreation.

Now Dr. Inon Scharf of Tel Aviv University's Department of Zoology and Dr. Oliver Martin of ETH Zurich have found that homosexual behavior in bugs is probably accidental in most cases. In the rush to produce offspring, bugs do not take much time to inspect their mates' gender, potentially leading to same-sex mating. The study, a comprehensive review of research on insects and spiders, was published in Behavioral Ecology and Sociobiology.

"Insects and spiders mate quick and dirty," Dr. Scharf observes. "The cost of taking the time to identify the gender of mates or the cost of hesitation appears to be greater than the cost of making some mistakes."

Friends without benefits

In birds and mammals, homosexual behavior has been shown to have evolutionary benefits. It provides "practice" for young adults and maintains alliances within groups. Scientists have recently tried to find explanations for similar behavior in insects, suggesting it could serve to prepare for heterosexual courtship, dispose of old sperm, discourage predators, and distract competitors.

But in reviewing research on some 110 species of male insects and spiders, the researchers found that the available evidence weakly supports such adaptive theories. In general there is no clear benefit to homosexual behavior in insects. The costs, on the other hand, can be considerable. Homosexual mating is at least as risky as the heterosexual kind, expending sperm, wasting time that could go toward other activities, and boosting the risk of injury, disease, and predation. In a previous study, the researchers found that all of these factors shorten the lives of heterosexually active males by an average of 25 percent. They expect homosexual behavior to be similarly costly.

And yet, in some species, up to 85 percent of males engage in homosexual behavior. The researchers say this is not because bugs directly benefit from the behavior, but because they mistake other males for females. Almost 80 percent of the cases of homosexual behavior the researchers appeared to be the result of misidentification or belated identification of gender. In some cases, males carry around the scents of females they have just mated with, sending confusing signals to other males. In other cases, males and females look so similar to one another that males cannot tell if potential mates are female until after they have mounted them.

Better unsafe than sorry

The researchers say insects and spiders probably have not evolved to be more discriminating in their mating choices because the cost of rejecting an opportunity to mate with a female is greater than that of mistakenly mating with a male. This explanation is supported by the fact that many species that exhibit homosexual behavior also mate with related species or inanimate objects, like beer bottles — indicating a general tendency toward misidentification. It is also possible that sexual enthusiasm in bugs is related to other evolutionarily beneficial traits, the researchers say.

"Homosexual behavior may be genomically linked to being more active, a better forager, or a better competitor," says Dr. Schart. "So even though misidentifying mates isn't a desirable trait, it's part of a package of traits that leaves the insect better adapted overall."

To confirm their theory, the researchers plan to study the conditions that make homosexual behavior more or less likely in bugs. They also want to look more deeply into male resistance to homosexual mating.

Israel Prize Awarded to TAU Biochemist for Research into Molecular Biology and Proteins
1/29/2013

Prof. Nathan Nelson wins Israel's top honor

Prof. Nathan Nelson of Tel Aviv University's Department of Biochemistry and Molecular Biology and Renewable Energy Center has been awarded the 2012 Israel Prize in the field of Life Sciences. The prize will be awarded in Jerusalem on the eve of Israel's Independence Day in April 2013.

An expert in biochemistry and molecular biology, Prof. Nelson is internationally renowned for his research into cell membrane molecular proteins and complexes. His most significant achievements include the isolation and structural determination of super-complexes involved in cellular energy transduction, including solving the structure of the plant PSI super-complex — a complicated protein system that governs the process of photosynthesis. He is additionally credited with the discovery and functional determination of genes coding various neurotransmitter transporters, metal-ion transporters, and others.

A step forward for renewable energy

Prof. Nelson is now employing his experience in photosynthesis as a researcher at the Renewable Energy Center, working to develop a clean and sustainable energy source.

The winner of many prestigious prizes in Israel and abroad, he is also a member of the European Organization for Excellence in Life Sciences and has served as the president of the Israel Society for Biochemistry and Molecular Biology and the director of the Daniella Rich Institute for Structural Biology. He has more than 250 published articles to his credit and over 15,000 citations in academic articles globally.

Tel Aviv University is proud to add number 74 to its list of recipients of the Israel Prize. The prizes are given every year by the state of Israel to those who have displayed excellence in their fields of study or made a strong contribution to Israeli culture.

Into the Mind of the Common Fruit Fly
9/24/2012

Fly neurons could reveal the root of Alzheimer's disease, says a TAU researcher

Although they're a common nuisance in the home, fruit flies have made great contributions to research in genetics and developmental biology. Now a Tel Aviv University researcher is again turning to this everyday pest to answer crucial questions about how neurons function at a cellular level — which may uncover the secrets of neurological disorders such as Alzheimer's disease.

Approximately 75 percent of the genes that are related to diseases in humans are also to be found in the fly, says Ya'ara Saad, a PhD candidate in the lab of Prof. Amir Ayali at TAU's Department of Zoology and the Sagol School of Neurosciences. There are many similarities in the functioning of the nervous system in both organisms, and by observing how neuronal networks taken from the fly grow and function outside of the body, there are many clues to the way human neuronal cells interact and the factors that influence their viability and physiology.

Saad's work, which has been published in the Journal of Molecular Histology, could help researchers to better understand how individual neurons are physically and chemically altered in response to disease and therapeutic intervention, and lead to new treatments.

Testing medications cell by cell

Saad is exploring how neural networks develop one neuron at a time. In the lab, the researchers break the fly's nervous system down into single cells, separate these cells, then place them at a distance from each other in a Petri dish. After a few days, the neurons begin to grow towards one another and establish connections, and then migrate to form clusters of cells. Finally, they re-organize themselves to form a sophisticated network, says Saad. Because these experiments uniquely allow researchers to concentrate on individual neurons, they can perform specific measurements of proteins, note electrical activity, watch synapses develop, and see how physical changes take shape.

Saad and her fellow researchers are using this technique to observe how neurodegenerative diseases take over the neurons and to potentially test various medicinal interventions. In their experiments, one group of flies is genetically modified so that it expresses a peptide called Amyloid Beta, found in protein-based plaques of human Alzheimer's disease patients. The results of these studies are then compared to those of a non-modified control group. Both strains of flies are provided by Prof. Daniel Segal of TAU's Department of Molecular Microbiology and Biotechnology.

Previous studies performed on flies expressing Amyloid Beta showed that they demonstrate Alzheimer's-like symptoms such as motor problems, impaired learning capabilities, and shorter lifespans. While this peptide has been researched for quite some time, scientists still do not know how it functions. Saad says her work may help unlock the mystery of this function. "Now I can really get into the molecular operation of Amyloid Beta inside the cell. I can watch the dysfunction in the synapses, monitor the proteins involved, and record electrical activity in a much more accessible way," she says.

Testing pharmacological agents is as simple as putting the medication into the dish and following how the cells change in response, Saad explains. Her next step will be to test various medications and search for a treatment that restores normal function, morphology, and chemical make-up to the neurons.

The benefits of invertebrates

As one of the first organisms for which scientists cracked the entire genome, there is a wealth of genetic information about the fruit fly, making it an ideal subject for her research, explains Saad. Though fly brains are simpler than those of human brains, the neurons are the same size and structure, and possess similar chemical activity. With a life span of 30 days on average, flies have a short aging process, an important consideration for the study of neurodegenerative diseases.

"A lot of basic discoveries in neurobiology have been made on invertebrates. If you want to see things on a cellular level, there are a lot of advantages to using these models," says Saad. She also says that using insects instead of mammals as experimental subjects has an additional plus: no ethical approval is necessary until the research is advanced enough to move on to more sophisticated life forms.

TAU Researcher Says Plants Can See, Smell, Feel, and Taste
7/30/2012

Unlocking the secrets of plant genetics could lead to breakthroughs in cancer research and food security

Increasingly, scientists are uncovering surprising biological connections between humans and other forms of life. Now a Tel Aviv University researcher has revealed that plant and human biology is much closer than has ever been understood — and the study of these similarities could uncover the biological basis of diseases like cancer as well as other "animal" behaviors.

In his new book What a Plant Knows (Farrar, Straus and Giroux) and his articles in Scientific American, Prof. Daniel Chamovitz, Director of TAU's Manna Center for Plant Biosciences, says that the discovery of similarities between plants and humans is making an impact in the scientific community. Like humans, Prof. Chamovitz says, plants also have "senses" such as sight, smell, touch, and taste.

Ultimately, he adds, if we share so much of our genetic makeup with plants, we have to reconsider what characterizes us as human.

These findings could prompt scientists to rethink what they know about biology, says Prof. Chamovitz, pointing out that plants serve as an excellent model for experiments on a cellular level. This research is also crucial to food security, he adds, noting that knowledge about plant genetics and how plants sense and respond to their environment is central to ensuring a sufficient food supply for the growing population — one of the main goals of the Manna Center.

Seeing the light

One of the most intriguing discoveries of recent years is that a group of plant genes used to regulate responses to light is also part of the human DNA. These affect responses like the circadian rhythm, the immune system, and cell division.

A plant geneticist, Prof. Chamovitz was researching the way plants react to light when he discovered an group of genes that were responsible for a plant "knowing" whether it was in the light or in the dark. He first believed that these genes were specific to plant life, but was surprised to later identify the same group of genes in humans and animals.

"The same group of proteins that plants use to decide if they are in the light or dark is also used by animals and humans," Prof. Chamovitz says. "For example, these proteins control two seemingly separate processes. First, they control the circadian rhythm, the biological clock that helps our bodies keep a 24 hour schedule. Second, they control the cell cycle — which means we can learn more about mutations in these genes that lead to cancer." In experiments with fruit flies who had a mutated version of one of these genes, Prof. Chamovitz and his fellow researchers observed that the flies not only developed a fly form of leukemia, but also that their circadian rhythm was disrupted, leading to a condition somewhat like permanent jet-lag.

Plants use light as a behavioral signal, letting them know when to open their leaves to gather necessary nutrients. This response to light can be viewed as a rudimentary form of sight, contends Prof. Chamovitz, noting that the plants "see" light signals, including color, direction, and intensity, then integrate this information and decide on a response. And plants do all this without the benefit of a nervous system.

And that's not the limit of plant "senses." Plants also demonstrate smell — a ripe fruit releases a "ripening pheromone" in the air, which is detected by unripe fruit and signals them to follow suit — as well as the ability to feel and taste. To some degree, plants also have different forms of "memory," allowing them to encode, store, and retrieve information.

Just like us

Beyond the genes that regulate responses to light, plants and humans share a bevy of other proteins and genes — for example, the genes that cause cystic fibrosis and breast cancer. Plants might not come down with these diseases, but the biological basis is the same, says Prof. Chamovitz. Because of this, plants are an excellent first stop when looking for a biological model, and could replace or at least enhance animal models for human disease in some types of research.

He is working alongside Prof. Yossi Shiloh, Israel Prize winner and incumbent of the David and Inez Myers Chair of Cancer Genetics at Tel Aviv University's Sackler Faculty of Medicine, to understand how the genes Chamovitz discovered function in protecting human cells from radiation.


Wiring Bats for Neuroscience Research
7/9/2012

TAU uses GPS and cutting-edge technologies with a first-ever captivity-bred bat colony

Mysterious creatures that thrive in the dark, bats have long been associated with witchcraft, vampires, and black magic. But according to Dr. Yossi Yovel of Tel Aviv University's Department of Zoology at Tel Aviv University, we have much to learn from these highly intelligent winged mammals. Now he is developing the world's first bat colony born and raised in captivity to unlock the secrets of behavior and cognition, including social hierarchy and structure, communication abilities, and memory.

The bats, which will be born in captivity but free to forage outside, are outfitted with high-tech sensors including GPS and ultra-sonic microphones to track their activities and interactions. In addition, Dr. Yovel's new state-of-the-art "flightrooms," acoustic rooms within the lab, are specially equipped to better analyze bat sonar.

This research, which has appeared in a number of journals including Science and PLoS Biology, is already unlocking secrets of the ways that the brain processes time and sound. It could also inspire future developments in robotics, sensors, and sonar technology, among other applications.

Taking neuroscience to the field

Along with high cognitive skills, bats have a sixth sense called echolocation. They and other biosonar animals such as dolphins send ultrasonic "pings" into the environment to identify the type and location of objects by the "shape" of the returning sound. Though man-made sonar and radar technology is inspired by nature, the bat-brain's ability to measure time within hundreds of nanoseconds and distances within less than a millimetre remains a riddle.

Until now, says Dr. Yovel, scientists were ill equipped to learn more about the behavior and functioning of bats. No sensors were light or small enough to attach to the animals, which often weigh only 30 grams or less. But with new sensors weighing less than five grams and novel GPS systems, bats can be observed in their natural condition as part of a research field that he calls "neuroecology."

Though most work in neuroscience is conducted in the lab, this environment is unnatural, says Dr. Yovel. TAU's bat colony is called an "imprinted colony" because despite being born in lab facilities and returning to their artificial "home" roosts daily, the bats are free to forage outside and behave as wild bats do. The GPS sensors relay information on where the bat has been, and sonic microphones record their social communication and echolocation practices. In the future, he hopes to mount cameras on the bats and even measure their brain activity with portable EEG devices.

High-speed perception

Equipped with over 100 sonic microphones and high-speed video cameras to the record bats' signals and behavior, Dr. Yovel's "flightrooms" seek to unlock mysteries of the working of the mammal's brain — which processes information at a speed that no machine can match. "Bats must make super-quick decisions when chasing tiny insects while flying at speeds of up to 50 kilometers per hour," he says.

The accuracy of biosonar is well known. Bats can identify different plant types by the shape of the ultrasonic sound that returns from them. And Dr. Yovel is researching the possibility the animals can identify each other as well by the different "sound pictures" that their unique features create. But another factor to consider is how quickly this information is processed.

"Time coding in the brain is something that we don't understand well," Dr. Yovel says. "We don't know how neurons that work on a time scale of milliseconds can measure time with an accuracy of hundreds of nanoseconds. Since humans rely on vision, we can't accurately measure when something is perceived. But because bats emit sonar calls that can be recorded and analyzed, we have a window into the bat's brain," says Dr. Yovel. With ultra-sonic microphones designed to measure the incoming and outgoing of sonar signals, he can gather accurate information on the bats' decision-making processes. This could answer the question of whether a specific network in the brain governs time coding.

Besides having applications in sonar and radar technologies, the research also contributes to understanding the limits and functioning of the brain, he says, noting that he is also attempting to use Functional Magnetic Resonance Imaging (fMRI) to measure bats' brain activity for the first time.

Naked Mole Rat May Hold the Secret to Long Life
7/2/2012

High levels of brain-protecting protein are unique in the rodent, says TAU researcher

Compared to the average three year life span of a common rat, the 10 to 30 year life of the naked mole rat, a subterranean rodent native to East Africa, is impressive. And compared to the human body, the body of this rodent shows little decline due to aging, maintaining high activity, bone health, reproductive capacity, and cognitive ability throughout its lifetime. Now a collaborative of researchers in Israel and the United States is working to uncover the secret to the small mammal's long — and active — lifespan.

Dr. Dorothee Huchon of Tel Aviv University's Department of Zoology, Prof. Rochelle Buffenstein of the University of Texas Health Science Center in San Antonio, and Dr. Yael Edrey of the City College of New York are working together to determine whether the naked mole rat's unusually high levels of NRG-1, a neuroprotecting protein, is behind the naked mole rat's three-decade life span. Because rodents have an 85 percent genetic similarity to humans, it may hold the key to a longer and healthier life for us as well.

This research has been published in the journal Aging Cell.

A family trait?

Genetic analysis comparing the mole rat with several other rodent species revealed that high levels NRG-1 in adults correlated with a longer life span. Of all the species the researchers studied, the naked mole rat had the most plentiful and long-lasting supply of the protein, maintaining a consistent level throughout its lifetime. It is concentrated in the cerebellum, the part of the brain important to motor control.

Dr. Huchon, an evolutionary biologist, joined the project to lend her expertise on rodent genetics. She studied seven species of rodents, including guinea pigs, mice, and mole rats, to determine the genetic relationships between them. Her analysis revealed that the correlation between life span and NRG-1 levels was independent of evolutionary lineage — meaning that it was unique to the naked mole rat, not a common trait of these rodent species.

Prof. Buffenstein and Edrey monitored NRG-1 levels in a population of naked mole rats ranging in age from one day to 26 years. They found that throughout their lives, levels of NRG-1, essential for normal brain functioning, were sustained. The protein is a neuroprotector, safeguarding the integrity of neurons, which may explain why naked mole rats are able to live so healthfully for such a long period of time.

Shaping future aging research

This discovery is an important first step towards understanding how aging — and the NRG-1 protein in particular — functions in these interesting animals, says Dr. Huchon. Future research could reveal how NRG-1 helps to maintain neuron integrity and lead to discoveries about human aging as well.

The naked mole rat, a burrowing rodent that lives in colonies much like those of ants, has already proven to be an excellent tool for aging and biomedical research because it is resistant to cancer and maintains protein integrity in the brain despite being exposed to oxidative damage, Dr. Huchon says.

Looking for the Next American Hyrax?
6/28/2012

Audience-loving animals express multiple traits through their songs, say TAU researchers

If popular karaoke bars and the long audition lines for American Idol demonstrate anything, it's that people like to express themselves through song — and the bigger the audience, the better. Now researchers at Tel Aviv University have found the same trait in small, rodent-like mammals called hyraxes, indigenous to Africa and the Middle East.

According to Prof. Eli Geffen and PhD candidate Amiyaal Ilany of TAU's Department of Zoology, hyrax vocalizations or "songs" go a long way towards communicating the singer's unique identity. Each one has unique songs that communicate a variety of information such as the singer's age, social rank, hormone levels, and size. And preliminary data suggests that the hyraxes prefer to sing when they have a more alert audience, taking the opportunity to promote themselves.

Understanding the function of the hyrax song will shed new light on animal communications, says Prof. Geffen, who notes that while birds are well known in the animal kingdom for singing, more complex vocalizations are rare in mammals. It's a model for learning how animals emit and receive signals, and what they understand from these communication channels, adds Ilany.

Their research, done in collaboration with Dr. Lee Koren of the University of Calgary and Adi Barocas of the University of Wyoming, and has been published in a number of journals including PLoS ONE and Behavioral Ecology and Sociobiology.

(Click here to listen to a sample of the hyrax song.)

Playing to the audience

A wealth of information is encoded in a hyrax song, which can continue for five to 10 minutes at a time.Identity, age, hormone levels, or social rank have the capacity to alter the songs, explain the researchers, who have been studying the same hyrax population for the last 13 years at the Ein Gedi nature reserve near the Dead Sea. "The long duration is a major strength of this project because we now know a lot about each individual animal," explains Ilany, including the details of their birth, life history, and social standing. "We can recognize this information encoded in song because we know them that well."

Using vocalization to signify identity is not without precedent. Many animals have the ability to identify another individual member of the same species by sound, say the researchers, because vocal sounds are unique to the individual that makes them. Flamingo mothers returning to the colony recognize their chicks by sound, for example. And of course humans can, too — recognizing the voice on the other end of the telephone before the caller introduces himself.

Beyond the information that is being communicated in the song itself, the function, context, and reception of the song are also significant. Singing hyraxes, who are almost exclusively male, are more likely to sing when they have an alert audience to listen to them. Prof. Geffen believes that perhaps the hyraxes use singing as a tool to promote themselves and facilitate communication with the other hyraxes.

Call and response?

In some cases, another male hyrax will respond with a song of its own, says Ilany. The researchers are now working to discover exactly what prompts this two-way communication. They are in the process of conducting "playback" experiments in which recorded hyrax songs are played to groups of hyraxes to see if different messages elicit different listener responses. For example, is a song that communicates a high social ranking more likely to get a response? The researchers are also testing the success of these self-advertisements by measuring whether hyraxes that sing in specific ways have higher success rates in finding mates and siring offspring.

There are still many questions left to answer, say the researchers, noting that many research groups around the world are attempting to decode animal communication systems. Eventually the aim is to create a "big picture" of how vocal communication works in this system, says Prof. Geffen, whose research has already gone a long way towards understanding communication in the animal world.

The Developing Genome?
2/13/2012

Since Charles Darwin first put forth the theory of evolution, scientists have been trying to unlock the mysteries of genetics. But research on the genome — the organism's entire hereditary package encoded in DNA and RNA — has been less extensive. There is a tendency to think of the genome as a static and passive container of information, says Dr. Ehud Lamm of Tel Aviv University's Cohn Institute for the History and Philosophy of Science and Ideas.

In the Proceedings of the 23rd Annual Workshop on the History and Philosophy of Science, Dr. Lamm has introduced a critical new paradigm that redefines the genome as a dynamic structure that can impact genes themselves. "When you try to explain human society by reducing it to individuals, you neglect the fact that people are also shaped by their social environment. The picture is bidirectional," he says, explaining that the relationship between genes and genomes is comparable. "Genomes have a physiology — and genes are a manifestation of this."

His reconception of the genome could change both biological discourse and research. Focusing on notions such as genomic response to stress factors, his theoretical work has the potential to provide deeper insight into how organisms develop and evolve.

Changing genetic research

Historically, genetic research has relegated understanding of the genome to the background, says Dr. Lamm. Past theories that regarded the capacity of the genome to respond to its environment were largely dismissed. But the concept of the genome as a mere collection of genes is a hindrance to research, he says. Based on current empirical knowledge from the fields of genetics, epigenetics, and genomics as well as "thought experiments," a tool used by scientists and philosophers to analyze situations and experimental conditions, Dr. Lamm is bringing to light the consequences of a new perspective on the genome.

From its embryonic development and continuing throughout our lives, the three-dimensional structure of the genome is changing constantly. The subtle relationship between genes and genomes impacts properties such as recessivity and dominance — a result of the developmental system rather than an intrinsic genetic property — and the process of how genes are inherited.

Lamm calls mechanisms that are involved in genomic changes "genomic epigenetic mechanisms" (GEMs) and highlights their importance for understanding the evolution of both genomes and organisms. Some GEMs are activated under conditions of ecological or genomic stress and can lead to changes that are subsequently inherited, contributing to the evolutionary process.

Although research into genomic structure and dynamics is ongoing, existing information can be used to reassess central notions in evolutionary biology. Ultimately, the mechanisms of the genome impact how, when, and in what way genetic material acts, as well as the physiology of cells themselves.

Building a new conceptual framework

So far, no useful theoretical framework exists to help scientists conceptualize the genome and the genes as a developmental system. Dr. Lamm hopes to provide it.

"The time is ripe to start thinking about how the genome and genes work as a system. With a gene-centric point of view, central concepts in genetics are problematic, most critically the gene concept itself. Considering the genome in addition to the gene might fill the gaps," concludes Dr. Lamm. With better conceptual tools, scientists can become more adept at thinking about these crucial biological systems.

Brain's Connective Cells Are Much More Than Glue
12/29/2011

Glia cells, named for the Greek word for "glue," hold the brain's neurons together and protect the cells that determine our thoughts and behaviors, but scientists have long puzzled over their prominence in the activities of the brain dedicated to learning and memory. Now Tel Aviv University researchers say that glia cells are central to the brain's plasticity — how the brain adapts, learns, and stores information.

According to Ph.D. student Maurizio De Pittà of TAU's Schools of Physics and Astronomy and Electrical Engineering, glia cells do much more than hold the brain together. A mechanism within the glia cells also sorts information for learning purposes, De Pittà says. "Glia cells are like the brain's supervisors. By regulating the synapses, they control the transfer of information between neurons, affecting how the brain processes information and learns."

De Pittà's research, led by his TAU supervisor Prof. Eshel Ben-Jacob, along with Vladislav Volman of The Salk Institute and the University of California at San Diego and Hugues Berry of the Université de Lyon in France, has developed the first computer model that incorporates the influence of glia cells on synaptic information transfer. Detailed in the journal PLoS Computational Biology, the model can also be implemented in technologies based on brain networks such as microchips and computer software, Prof. Ben-Jacob says, and aid in research on brain disorders such as Alzheimer's disease and epilepsy.

Regulating the brain's "social network"

The brain is constituted of two main types of cells: neurons and glia. Neurons fire off signals that dictate how we think and behave, using synapses to pass along the message from one neuron to another, explains De Pittà. Scientists theorize that memory and learning are dictated by synaptic activity because they are "plastic," with the ability to adapt to different stimuli.

But Ben-Jacob and colleagues suspected that glia cells were even more central to how the brain works. Glia cells are abundant in the brain's hippocampus and the cortex, the two parts of the brain that have the most control over the brain's ability to process information, learn and memorize. In fact, for every neuron cell, there are two to five glia cells. Taking into account previous experimental data, the researchers were able to build a model that could resolve the puzzle.

The brain is like a social network, says Prof. Ben-Jacob. Messages may originate with the neurons, which use the synapses as their delivery system, but the glia serve as an overall moderator, regulating which messages are sent on and when. These cells can either prompt the transfer of information, or slow activity if the synapses are becoming overactive. This makes the glia cells the guardians of our learning and memory processes, he notes, orchestrating the transmission of information for optimal brain function.

New brain-inspired technologies and therapies

The team's findings could have important implications for a number of brain disorders. Almost all neurodegenerative diseases are glia-related pathologies, Prof. Ben-Jacob notes. In epileptic seizures, for example, the neurons' activity at one brain location propagates and overtakes the normal activity at other locations. This can happen when the glia cells fail to properly regulate synaptic transmission. Alternatively, when brain activity is low, glia cells boost transmissions of information, keeping the connections between neurons "alive."

The model provides a "new view" of how the brain functions. While the study was in press, two experimental works appeared that supported the model's predictions. "A growing number of scientists are starting to recognize the fact that you need the glia to perform tasks that neurons alone can't accomplish in an efficient way," says De Pittà. The model will provide a new tool to begin revising the theories of computational neuroscience and lead to more realistic brain-inspired algorithms and microchips, which are designed to mimic neuronal networks.

To read the article, see:
http://www.ploscompbiol.org/article/info%3Adoi%2F10.1371%2Fjournal.pcbi.1002293

The Disappearance of the Elephant Caused the Rise of Modern Man
12/12/2011

Elephants have long been known to be part of the Homo erectus diet. But the significance of this specific food source, in relation to both the survival of Homo erectus and the evolution of modern humans, has never been understood — until now.

When Tel Aviv University researchers Dr. Ran Barkai, Miki Ben-Dor, and Prof. Avi Gopher of TAU's Department of Archaeology and Ancient Near Eastern Studies examined the published data describing animal bones associated with Homo erectus at the Acheulian site of Gesher Benot Ya'aqov in Israel, they found that elephant bones made up only two to three percent the total. But these low numbers are misleading, they say. While the six-ton animal may have only been represented by a tiny percentage of bones at the site, it actually provided as much as 60 percent of animal-sourced calories.

The elephant, a huge package of food that is easy to hunt, disappeared from the Middle East 400,000 years ago — an event that must have imposed considerable nutritional stress on Homo erectus. Working with Prof. Israel Hershkovitz of TAU's Sackler Faculty of Medicine, the researchers connected this evidence about diet with other cultural and anatomical clues and concluded that the new hominids recently discovered at Qesem Cave in Israel — who had to be more agile and knowledgeable to satisfy their dietary needs with smaller and faster prey — took over the Middle Eastern landscape and eventually replaced Homo erectus.

The findings, which have been reported in the journal PLoS One, suggest that the disappearance of elephants 400,000 years ago was the reason that modern humans first appeared in the Middle East. In Africa, elephants disappeared from archaeological sites and Homo sapiens emerged much later — only 200,000 years ago.

The perfect food package

Unlike other primates, humans' ability to extract energy from plant fiber and convert protein to energy is limited. So in the absence of fire for cooking, the Homo erectus diet could only consist of a finite amount of plant and protein and would have needed to be supplemented by animal fat. For this reason, elephants were the ultimate prize in hunting — slower than other sources of prey and large enough to feed groups, the giant animals had an ideal fat-to-protein ratio that remained constant regardless of the season. In short, says Ben-Dor, they were the ideal food package for Homo erectus.

When elephants began to die out, Homo erectus "needed to hunt many smaller, more evasive animals. Energy requirements increased, but with plant and protein intake limited, the source had to come from fat. He had to become calculated about hunting," Ben-Dor says, noting that this change is evident in the physical appearance of modern humans, lighter than Homo erectus and with larger brains.

To confirm these findings, the researchers compared archaeological evidence from two sites in Israel: Gesher B'not Yaakov, dating back nearly 800,000 years and associated with Homo erectus; and Qesem Cave, dated 400,000 to 200,000 years ago. Gesher B'not Yaakov contains elephant bones, but at Qesem Cave, which is bereft of elephant bones, the researchers discovered signs of post-erectus hominins, with blades and sophisticated behaviors such as food sharing and the habitual use of fire.

Evolution in the Middle East

Modern humans evolved in Africa 200,000 years ago, says Dr. Barkai, and the ruling paradigm is that this was their first worldwide appearance. Archaeological records tell us that elephants in Africa disappeared alongside the Acheulian culture with the emergence of modern humans there. Though elephants can be found today in Africa, few species survived and no evidence of the animal can be found in archaeological sites after 200,000 years ago. The similarity to the circumstances of the Middle East 400,000 years ago is no coincidence, claim the researchers. Not only do their findings on elephants and the Homo erectus diet give a long-awaited explanation for the evolution of modern humans, but they also call what scientists know about the "birth-place" of modern man into question.

Evidence from the Qesem Cave corroborates this revolutionary timeline. Findings from the site dated from as long as 400,000 years ago, clearly indicate the presence of new and innovative human behavior and a new human type. This sets the stage for a new understanding of the human story, says Prof. Gopher.

To read a reprint of the paper that appeared in PLoS One, click here:
http://www.aftau.org/site/DocServer/elephants_paper.pdf?docID=16321

Fungi: Another Tool in Bacteria's Belt?
11/28/2011

Bacteria and fungi are remarkably mobile. Now researchers at Tel Aviv University have discovered that the two organisms enjoy a mutually beneficial relationship to aid them in that movement — and their survival.

Fungal spores can attach themselves to bacteria, "hitching a ride" wherever the bacteria travel. And while this allows them to travel further than they would on their own, says Prof. Eshel Ben-Jacob of TAU's Raymond and Beverly Sackler School of Physics and Astronomy, it's certainly not a one-way street. Bacteria live largely in the rhizosphere — the environment that surrounds plant roots — where air pockets can interrupt their progress, he explains. When faced with a gap, the bacteria can drop the fungal spores to form a bridge, and continue across the chasm.

The research, which was recently published in PNAS, was done in collaboration with Dr. Colin J. Ingham of Wageningen University and JBZ Hospital in the Netherlands, the paper's lead author; post-doctoral fellow Dr. Alin Finkelshtein; and graduate student Oren Kalishman working in Prof. Ben-Eshel's TAU lab.

This discovery contributes to our understanding of the way bacteria and fungi spread. Confirmation that the two organisms work in collaboration will help scientists fight disease-causing bacteria, or promote the spread of "good kinds" of bacteria or fungi, such as those that contribute to the health of plants. "In addition we now know that when you fight fungi, you are also fighting bacteria — and vice versa," notes Prof. Ben-Jacob.

A bridge to mutual survival

Mobile or "motile" bacteria, such as Paenibacillus vortex, are known to be able to carry cargo. With this in mind, the researchers were motivated to test whether P. vortex would be able to carry non-motile fungi, aiding in its dispersion. In fact, they observed that not only can the bacteria transport the fungi over long distances, like humans being carried by air travel, but they are also able to recover fungal spores from life-threatening locations, moving them to new and more favorable places where they can germinate and start new colonies. "The bacteria entrap the spores and wrap them in their flagella, which are like arms," explains Prof. Ben-Jacob. "This is similar to the way the Lilliputians moved the giant Gulliver by trapping him in a mesh of ropes."

But the bacteria's services aren't free. In an experiment, the researchers created air gaps or "canyons" too large for bacteria to cross. When confronted with this challenge, the bacteria used the fungi's mycelia — branch-like structures on the spores — as natural bridges, enabling them to cross otherwise impenetrable gaps, notes Dr. Ingham.

"We see that upon encountering impossible terrains, the bacteria can bring fungal spores to help," Prof. Ben-Jacob continues. "The bacteria allow the fungi to germinate and form a colony, and then use the mycelia to cross obstacles."

Taking over new territories

Ultimately, this collaboration helps both the bacteria and the fungi to spread and thrive in highly competitive habitats. It's a sophisticated survival strategy, say the researchers, and contributes to our understanding of bacteria as smart organisms with an intricate social life. "The bacteria never let us down," Prof. Ben-Jacob says with a smile. "Just present them with a new challenge and you can be sure they'll provide new surprises."

These observations can also be applied to agriculture and medicine, showing new mechanisms by which bacteria and fungi can help one another to invade new territories in the rhizosphere — as well as in hospitals and within our own bodies.

Smart Swarms of Bacteria Inspire Robotics Researchers
11/17/2011

TAU model discovers adaptable decision-making in bacteria communities

Much to humans' chagrin, bacteria have superior survival skills. Their decision-making processes and collective behaviors allow them to thrive and even spread efficiently in difficult environments.

Now researchers at Tel Aviv University have developed a computational model that better explains how bacteria move in a swarm — and this model can be applied to man-made technologies, including computers, artificial intelligence, and robotics. Ph.D. student Adi Shklarsh — with her supervisor Prof. Eshel Ben-Jacob of TAU's Sackler School of Physics and Astronomy, Gil Ariel from Bar Ilan University and Elad Schneidman from the Weizmann Institute of Science — has discovered how bacteria collectively gather information about their environment and find an optimal path to growth, even in the most complex terrains.

Studying the principles of bacteria navigation will allow researchers to design a new generation of smart robots that can form intelligent swarms, aid in the development of medical micro-robots used to diagnose or distribute medications in the body, or "de-code" systems used in social networks and throughout the Internet to gather information on consumer behaviors. The research was recently published in PLoS Computational Biology.

A dash of bacterial self-confidence

Bacteria aren't the only organisms that travel in swarms, says Shklarsh. Fish, bees, and birds also exhibit collective navigation. But as simple organisms with less sophisticated receptors, bacteria are not as well-equipped to deal with large amounts of information or "noise" in the complex environments they navigate, such as human tissue. The assumption has been, she says, that bacteria would be at a disadvantage compared to other swarming organisms.

But in a surprising discovery, the researchers found that computationally, bacteria actually have superior survival tactics, finding "food" and avoiding harm more easily than swarms such as amoeba or fish. Their secret? A liberal amount of self-confidence.

Many animal swarms, Shklarsh explains, can be harmed by "erroneous positive feedback," a common side effect of navigating complex terrains. This occurs when a subgroup of the swarm, based on wrong information, leads the entire group in the wrong direction. But bacteria communicate differently, through molecular, chemical and mechanical means, and can avoid this pitfall.

Based on confidence in their own information and decisions, "bacteria can adjust their interactions with their peers," Prof. Ben-Jacob says. "When an individual bacterium finds a more beneficial path, it pays less attention to the signals from the other cells. But at other times, upon encountering challenging paths, the individual cell will increase its interaction with the other cells and learn from its peers. Since each of the cells adopts the same strategy, the group as a whole is able to find an optimal trajectory in an extremely complex terrain."

Benefitting from short-term memory

In the computer model developed by the TAU researchers, bacteria decreased their peers' influence while navigating in a beneficial direction, but listened to each other when they sensed they were failing. This is not only a superior way to operate, but a simple one as well. Such a model shows how a swarm can perform optimally with only simple computational abilities and short term memory, says Shklarsh, It's also a principle that can be used to design new and more efficient technologies.

Robots are often required to navigate complex environments, such as terrains in space, deep in the sea, or the online world, and communicate their findings among themselves. Currently, this is based on complex algorithms and data structures that use a great deal of computer resources. Understanding the secrets of bacteria swarms, Shklarsh concludes, can provide crucial hints towards the design of new generation robots that are programmed to perform adjustable interactions without taking up a great amount of data or memory.

To read the article, see:
http://www.ploscompbiol.org/article/info%3Adoi%2F10.1371%2Fjournal.pcbi.1002177

To see Prof. Ben-Eshel's lecture entitled "Learning from Bacteria about Social Networks," visit:
http://www.youtube.com/watch?v=yJpi8SnFXHs


Amphibians: Beware Young Beetles' Deadly "Siren Call"
9/26/2011

In role reversal, carnivorous ground beetle stalks its amphibian prey, says TAU researcher

Ground beetles can immobilize and devour amphibian prey many times their size. Now Gil Wizen, a graduate student of Tel Aviv University's Department of Zoology, along with his supervisor Prof. Avital Gasith, has discovered that they have an additional advantage — the larvae of these beetles, like their fully grown adult counterparts, have a unique method for luring and feeding off amphibians.

Wizen's research revealed that, like the sirens who lured Ulysses' sailors to their demise, larvae have a lethal method for attracting the attention of amphibians — tricking the toads into thinking they will be tasty prey.

In a dry country like Israel, amphibian species are already being threatened with extinction. Greater understanding of the larvae's habits and their impact on the amphibian population will have significant impact towards an accurate environmental risk assessment, says Wizen. His research was recently published in PLoS ONE.

Reversing the role of predator and prey

The project was set in motion when toad specimens were brought to Wizen's lab for observation. Discovering that some of the specimens had larvae attached to their bodies, the researchers noted over time that the larvae spent their entire life cycle feeding off the toads.

Adult beetles, Wizen says, ambush and then paralyze the amphibians by making a small incision into their back, perhaps severing the spinal cord or cutting a muscle so they cannot jump away. The beetles then consume and kill the amphibian. But the researchers wanted to know how this David-and-Goliath feat was accomplished, and collected more information on the larvae themselves and how they first attracted the amphibians' attention.

Amphibians hunt based on their prey's movement, Wizen explains. Larvae, immobile on the ground, attract the amphibian's attention by performing a sequence of movements, including opening their jaws and moving their antennae side to side, almost like a dance. When the amphibian tries to grab the larvae with its tongue, however, the larvae jumps and attaches itself to the amphibian with its jaws.

"It's really a predator-prey role reversal — the insect actually draws in its potential predator instead of avoiding it," says Wizen. "It's quite a unique phenomenon."

An unbeatable opponent

Although they are many times the larvae's size, the amphibians don't stand a chance, says Wizen. Researchers did observe some instances where the amphibian was quicker and managed to ingest the larvae, but success didn't last — in every case, the amphibian ended up regurgitating the larvae, which then attached itself to the amphibian's mouth.

Once the larvae has attached, the amphibian's diagnosis is grim. If the larvae are in the first stage of development, they will feed off the amphibian's body fluids like an exoparasite, and eventually, when they need to moult into its next developmental stage, they will fall off the amphibian's body, leaving a nasty scar.

But in the second or third stages of development, Wizen explains, the larvae begin to chew on the amphibians themselves, leaving behind nothing but bones.

To see a video of a larva's "dance" to lure its amphibian prey, visit:
http://video.tau.ac.il/Lectures/Life_Sciences/2009/Gil/luring.asx


Repairing Our Inner Clock with a Two-Inch Fish
7/21/2011

Humans and zebrafish share mechanisms that regulate our circadian system, says TAU researcher

Circadian rhythms — the natural cycle that dictates our biological processes over a 24-hour day — does more than tell us when to sleep or wake. Disruptions in the cycle are also associated with depression, problems with weight control, jet lag and more. Now Prof. Yoav Gothilf of Tel Aviv University's Department of Neurobiology at the George S. Wise Faculty of Life Sciences is looking to the common zebrafish to learn more about how the human circadian system functions.

Prof. Gothilf and his Ph.D. student Gad Vatine, in collaboration with Prof. Nicholas Foulkes of the Karlsruhe Institute for Technology in Germany and Dr. David Klein of the National Institute of Health in Maryland, has discovered that a mechanism that regulates the circadian system in zebrafish also has a hand in running its human counterpart.

The zebrafish discovery provides an excellent model for research that may help to develop new treatments for human ailments such as mental illness, metabolic diseases or sleep disorders. The research appears in the journals PLoS Biology and FEBS Letters.

A miniature model

Zebrafish may be small, but their circadian system is similar to those of human beings. And as test subjects, says Prof. Gothilf, zebrafish also have several distinct advantages: their embryos are transparent, allowing researchers to watch as they develop; their genetics can be easily manipulated; and their development is quick — eggs hatch in two days and the fish become sexually mature at three months old.

Previous research on zebrafish revealed that a gene called Period2, also present in humans, is associated with the fish's circadian system and is activated by light. "When we knocked down the gene in our zebrafish models," says Prof. Gothilf, "the circadian system was lost." This identified the importance of the gene to the system, but the researchers had yet to discover how light triggered gene activity.

The team subsequently identified a region called LRM (Light Responsive Model) within Period2 that explains the phenomenon. Within this region, there are short genetic sequences called Ebox, which mediate clock activity, and Dbox, which confer light-driven expression — the interplay between the two sequences is responsible for light activation. Based on this information, they identified the proteins which bind the Ebox and Dbox and trigger the light-induction of the Period2 gene, a process that is important for synchronization of the circadian system.

To determine whether a similar mechanism may exist in humans, Prof. Gothilf and his fellow researchers isolated and tested the human LRM and inserted it into zebrafish cells. In these fish cells, the human LRM behaved in exactly the same way, activating Period2 when exposed to light — and unveiling a fascinating connection between humans and the two-inch-long fish.

Shedding new light on circadian systems and the brain

Zebrafish and humans could have much more in common, Prof. Gothilf says, leading to breakthroughs in human medicine. Unlike rats and mice but like human beings, zebrafish are diurnal — awake during the day and asleep at night — and they have circadian systems that are active as early as two days after fertilization. This provides an opportunity to manipulate the circadian clock, testing different therapies and medications to advance our understanding of the circadian system and how disruptions, whether caused by biology or lifestyle, can best be treated.

Prof. Gothilf believes this model has further application to brain and biomedical research. Researchers can already manipulate the genetic makeup of zebrafish, for example, to make specific neurons and their synapses (the junctions between neurons in the brain) fluorescent — easy to see and track. "Synapses can be actually counted. This kind of accessible model can be used in research into degenerative brain disorders," he notes, adding that several additional research groups at TAU are now using zebrafish to advance their work.


Traumatizing Your DNA
3/23/2011

When the Human Genome Project ended a decade ago, scientists thought that they'd closed the lid on all that's to be known about our genes. But what they really did was open a Pandora's Box, says theoretical evolutionary biologist Prof. Eva Jablonka of Tel Aviv University's Cohn Institute for the History and Philosophy of Science and Ideas.

After sifting through hundreds of scientific studies concerned with epigenetics, Prof. Jablonka concludes that some of the effects of stress, cancer, and other chronic diseases we suffer from may be passed on to our offspring through deep and complicated underlying cellular mechanisms that we are just now beginning to understand.

Prof. Jablonka will discuss her findings at an epigenetics conference in North Carolina later this month.

The invisible threat

Epigenetic research suggests that the effects of stress and environmental pollution can be passed on to future generations without any obvious change or mutation in our DNA. The problem, Prof. Jablonka points out, is that we have no idea of the extent these effects will have on the human genome of the future.

"I am a story teller. I read a lot of information and develop theories about evolution. For the last 25 years, before it became a fad, I was interested in the transmission of information not dependent on DNA variations," Dr. Jablonka says. "Epigenetic inheritance is information about us that is not explicitly encoded in our genes. Two individuals may have identical genes, but the genes present very different characteristics. They can be genetically identical but different epigenetically."

In a 2009 paper for the Quarterly Review of Biology, Prof. Jablonka wrote about cellular epigenetic inheritance and explored some of the consequences of such inheritance for the study of evolution, also pointing to the importance of recognizing and understanding epigenetic inheritance for practical and theoretical issues in biology. She has since concluded that individuals can influence their heredity.

After reviewing the literature, she has found more than 100 examples of living organisms, from bacteria to human beings, demonstrating how our genes' expression can be altered and inherited.

"Stress is enormously important," Prof. Jablonka says. "It can affect the development of cancer and other chronic diseases, and may also have long term impacts on ecology." At the conclusion of the Human Genome Project, researchers hoped that the findings would provide relief from several diseases. "What they weren't prepared for," she continues, "is that genes really do so many things, and that gene expression patterns can be heritable. We can learn some things about diseases from our DNA, but it doesn't tell the whole story."

Is environmental pollution irreversible?

Stress can create near invisible effects on gene expression, effects that can be passed from mother or father to child. Some of this operates through microRNA, tiny RNA discovered about a decade ago which work as cellular "micro-managers." In addition, a process called DNA methylation alters gene function. Various processes "hidden" in chromosomes within the cells appear to be influenced by lifestyle and disease.

As a result, Prof. Jablonka advises that it might be prudent to reconsider all the environmental pollutants being introduced into the planet's ecosystems. Some pesticides and fungicides are androgen suppressors and have many effects on gene expression — and these effects can be inherited. Whether and how future generations can endure with these altered gene functions are still open questions, she says.


Angling to Understand Nature's Design
3/9/2011

A cheetah can go from zero to 100 in a matter of seconds — without the benefit of a sportscar's gearbox. Now a Tel Aviv University marine biologist is working in a field of biomechanics called biomimicry, or the designs of nature, to replicate them in robots, airplanes, and nanotechnology.

Concentrating on fish, Dr. Roi Holzman of Tel Aviv University's Department of Zoology at the George S. Wise Faculty of Life Sciences is studying why animals exhibit structures far more complex than human engineers could dream up. An organism's ability to perform life-sustaining tasks like eating, moving, and reproducing depend on a number of biological traits that work together. To capture their prey, for example, fish generate a vacuum cleaner-like "suction power" by unfolding bones in their skull to open the mouth. Lasting less than a blink of the eye and involving many moveable bones, this feeding gesture is amazingly complicated — much more complicated than the way humans and terrestrial vertebrates eat, Dr. Holzman says.

These observations led Dr. Holzman to investigate whether the complex behaviors animals perform evolved differently than simpler ones — and whether these behaviors can be replicated in technology to benefit human beings.

It takes small and big mouths

Consider the complicated transmission of an 18-wheeler. In low gear, it can pull heavy loads, and in high gear, it can go fast, but it can't do both at the same time. A low gear can't generate a high speed, and a high gear doesn't support a lot of torque. Is the same trade-off true in nature when it comes to complicated physical behaviors? Dr. Holzman is applying the question to his test subjects, the North American bluegill and largemouth bass.

"Engineers will tell you that trade-offs are the basics in biomechanics," says Holzman. "But I want to know if becoming good at one task in nature means the performance of other tasks will suffer."

Filming fish in motion with a high-speed video camera, Dr. Holzman measured mouth and skull movements and applied them to a hydrodynamic model developed in the laboratory. His team was able to predict if a fish, based on its evolutionary features, would be able to catch its prey in a variety of different scenarios.

Any small-mouthed fish, like the bluegill, creates a strong flow in the front of its mouth, exerting that flow to capture its prey. But its small mouth size also means that the flow cannot extend too far in front of its mouth. A larger-mouthed fish like the largemouth bass exerts less force on its prey, but can gulp more of the water in front of it, extending the reach of the force.

"Evolving" a back-up plan

Holzman and his colleagues at UC Davis found that the fish employ several "back-up mechanisms" to compensate for biomechanical limitations. Nature appears to have built wiggle room into the evolutionary process.

Combining a number of complex traits, fish and other animals may have been able to avoid the high price of trade-offs found in existing technology, says Holzman. This news bodes well for engineers of the future, who may learn from animals how to build much more complicated machines to improve energy efficiency, for example.

His conclusion is that animals, including humans, are very complicated machines for a reason. Whether exploring the complex biological structures in fish or the muscles in human legs, there appear to be some very important "design" considerations at work. These may not be optimal in themselves, but when they "collaborate" with other systems they can perform a range of tasks effectively.

Dr. Holzman can't say if he'll be able to solve medical whys, such as the reason for our seemingly useless tonsil, pancreas or wisdom teeth. But he does believe that by looking at animal evolution we see how complexity grows. "Considering all this in addition to cell types, germ cell layers, and new and novel organs, I believe that the complexity of nature, and our bodies, benefits both our performance and survival," he concludes.


Roaches Inspire Robotics
2/7/2011

Ask anyone who has ever tried to squash a skittering cockroach — they're masters of quick and precise movement. Now Tel Aviv University is using their maddening locomotive skills to improve robotic technology too.

Prof. Amir Ayali of Tel Aviv University's Department of Zoology says the study of cockroaches has already inspired advanced robotics. Robots have long been based on these six-legged houseguests, whose nervous system is relatively straightforward and easy to study. But until now, walking machines based on the cockroach’s movement have been influenced by outside observations and mainly imitate the insect's appearance, not its internal mechanics.

He and his fellow researchers are delving deeper into the neurological functioning of the cockroach. This, he says, will give engineers the information they need to design robots with a more compact build and greater efficiency in terms of energy, time, robustness and rigidity. Such superior robotics can be even used to explore new terrain in outer space.

This research was recently presented at the International Neuroethology conference in Spain as well as the Israeli Neuroscience Meeting in December.

Roach control systems as the ideal model

According to Prof. Ayali, it's clear why robotics have been inspired by these unsavory insects. A cockroach is supported by at least three legs at all times during movement, which provides great stability. "Not only do cockroaches arguably exhibit one of the most stable ways to walk, called a tripod gate," he explains, "but they move equally quickly on every kind of terrain. Their speed and stability is almost too good to be true."

In their lab, Prof. Ayali and his fellow researchers are conducting a number of tests to uncover the mysteries of the cockroach’s nervous system, studying how sensory feedback from one leg is translated to the coordination of all the other legs. Their analysis of the contribution of each leg is shared with collaborating scientists at Princeton University, who use the information to construct models and simulations of insect locomotion.

Insects, says Prof. Ayali, utilize information from the environment around them to determine how they will move. Sensors give them data about the terrain they are encountering and how they should approach it. How this information transfers to the insect’s legs is central to understanding how to mimic their locomotion.

An army of robotic insects

Cockroaches are not the only insects that have captured the scientific imagination. Projects that highlight both the flight of the locust and the crawling of the soft-bodied caterpillar are also underway.

Locusts are amazing flyers, Prof. Ayali notes. Scientists are studying both their aerodynamic build and their energy metabolism for long-distance flights. Recordings of their nervous systems and simultaneous video tracking to observe the movement of their wings during flight can be expected to lead to better technology for miniscule flying robots.

As for caterpillars, engineers are trying to recreate in soft-bodied robots what they call the creatures "endless degrees of freedom of movement." "Caterpillars are not confined by a stiff structure — they have no rigid skeletons," says Prof. Ayali. "This is exactly what makes them unique."


The Genius of Bacteria
1/24/2011

IQ scores are used to assess the intelligence of human beings. Now Tel Aviv University has developed a "Social-IQ score" for bacteria — and it may lead to new antibiotics and powerful bacteria-based "green" pesticides for the agricultural industry.

An international team led by Prof. Eshel Ben-Jacob of Tel Aviv University's Department of Physics and Astronomy and his research student Alexandra Sirota-Madi says that their results deepen science’s knowledge of the social capabilities of bacteria, one of the most prolific and important organisms on earth. "Bacteria are our worst enemies but they can also be our best friends. To better exploit their capabilities and to outsmart pathogenic bacteria, we must realize their social intelligence," says Prof. Ben-Jacob.

The international team was first to sequence the genome of pattern-forming bacteria, the Paenibacillus vortex (Vortex) discovered two decades ago by Prof. Ben-Jacob and his collaborators. While sequencing the genome, the team developed the first "Bacteria Social-IQ Score" and found that Vortex and two other Paenibacillus strains have the world's highest Social-IQ scores among all 500 sequenced bacteria. The research was recently published in the journal BMC Genomics.

Highly evolved communities

The impact of the team's research is three-fold. First, it shows just how "smart" bacteria can really be — a new paradigm that has just begun to be recognised by the science community today. Second, it demonstrates bacteria's high level of social intelligence — how bacteria work together to communicate and grow. And finally, the work points out some potentially significant applications in medicine and agriculture.

The researchers looked at genes which allow the bacteria to communicate and process information about their environment, making decisions and synthesizing agents for defensive and offensive purposes. This research shows that bacteria are not simple solitary organisms, or "low level" entities, as earlier believed — they are highly social and evolved creatures. They consistently foil the medical community as they constantly develop strategies against the latest antibiotics. In the West, bacteria are one of the top three killers in hospitals today.

The recent study shows that everyday pathogenic bacteria are not so smart: their S-IQ score is just at the average level. But the social intelligence of the Vortex bacteria is at the "genius range": if compared to human IQ scores it is about 60 points higher than the average IQ at 100. Armed with this kind of information on the social intelligence of bacteria, researchers will be better able to outsmart them, says Prof. Ben-Jacob.

This information can also be directly applied in "green" agriculture or biological control, where bacteria's advanced offense strategies and toxic agents can be used to fight harmful bacteria, fungi and even higher organisms.

Tiny biotechnology factories

Bacteria are often found in soil, and live in symbiotic harmony with a plant's roots. They help the roots access nutrients, and in exchange the bacteria eat sugar from the roots.

For that reason, bacteria are now applied in agriculture to increase the productivity of plants and make them stronger against pests and disease. They can be used instead of fertilizer, and also against insects and fungi themselves. Knowing the Social-IQ score could help developers determine which bacteria are the most efficient.

"Thanks to the special capabilities of our bacteria strain, it can be used by researchers globally to further investigate the social intelligence of bacteria," says co-author Sirota-Madi. "When we can determine how smart they really are, we can use them as biotechnology factories and apply them optimally in agriculture."

The international research team includes researchers from Israel, Holland, Russia and India.


Is the Hornet Our Key to Renewable Energy?
1/5/2011

As every middle-school child knows, in the process of photosynthesis, plants take the sun's energy and convert it to electrical energy. Now a Tel Aviv University team has demonstrated how a member of the animal kingdom, the Oriental hornet, takes the sun's energy and converts it into electric power — in the brown and yellow parts of its body — as well.

"The interesting thing here is that a living biological creature does a thing like that," says physicist Prof. David Bergman of Tel Aviv University's School of Physics and Astronomy, who was part of the team that made discovery. "The hornet may have discovered things we do not yet know." In partnership with the late Prof. Jacob Ishay of the university's Sackler Faculty of Medicine, Prof. Bergman and his doctoral candidate Marian Plotkin engaged in a truly interdisciplinary research project to explain the biological processes that turn a hornet's abdomen into solar cells.

The research team made the discovery several years ago, and recently tried to mimic it. The results show that the hornet's body shell, or exoskeleton, is able to harvest solar energy. They were recently published in the German journal Naturwissenschaften.

Discovering a new system for renewable energy?

Previously, entomologists noted that Oriental wasps, unlike other wasps and bees, are active in the afternoon rather than the morning when the sun is just rising. They also noticed that the hornet digs more intensely as the sun's intensity increases.

Taking this information to the lab, the Tel Aviv University team studied weather conditions like temperature, humidity and solar radiation to determine if and how these factors also affected the hornet's behavior, but found that UVB radiation alone dictated the change.

In the course of their research, the Tel Aviv University team also found that the yellow and brown stripes on the hornet abdomen enable a photo-voltaic effect: the brown and yellow stripes on the hornet abdomen can absorb solar radiation, and the yellow pigment transforms that into electric power.

The team determined that the brown shell of the hornet was made from grooves that split light into diverging beams. The yellow stripe on the abdomen is made from pinhole depressions, and contains a pigment called xanthopterin. Together, the light diverging grooves, pinhole depressions and xanthopterin change light into electrical energy. The shell traps the light and the pigment does the conversion.

A biological heat pump

The researchers also found a number of energy processes unique to the insect. Like air conditioners and refrigerators, the hornet has a well-developed heat pump system in its body which keeps it cooler than the outside temperature while it forages in the sun. This is something that's not easy to do, says Prof. Bergman.

To see if the solar collecting prowess of the hornet could be duplicated, the team imitated the structure of the hornet's body but had poor results in achieving the same high efficiency rates of energy collection. In the future, they plan to refine the model to see if this "bio-mimicry" can give clues to novel renewable energy solutions.

The research team also discovered that hornets use finely honed acoustic signals to guide them so they can build their combs with extraordinary precision in total darkness. Bees can at least see what they are doing, explains Prof. Bergman, but hornets cannot — it's totally dark inside a hornet nest.


Do Our Bodies' Bacteria Play Matchmaker?
12/2/2010

Could the bacteria that we carry in our bodies decide who we marry? According to a new study from Tel Aviv University, the answer lies in the gut of a small fruit fly.

Prof. Eugene Rosenberg, Prof. Daniel Segel and doctoral student Gil Sharon of Tel Aviv University's Department of Molecular Microbiology and Biotechnology recently demonstrated that the symbiotic bacteria inside a fruit fly greatly influence its choice of mates.

The research was done in cooperation with Prof. John Ringo of the University of Maine, and was recently published in the Proceedings of the National Academy of Sciences (PNAS).

Love, marriage and fruit flies

Based on a theory developed by Prof. Rosenberg and Dr. Ilana Zilber-Rosenberg, the scientists propose that the basic unit of natural selection is not the individual living organism, plant or animal, but rather a larger biological milieu called a holobiont. This milieu can include plant or animal life as well as their symbiotic partners. In the case of animals, these partners tend to be microorganisms like intestinal bacteria.

"Up to now, it was assumed that the host organism undergoes evolution on its own, while its symbiotic bacteria undergo their own evolution," Prof. Rosenberg says. "The mechanism that we discovered enables evolution to occur more rapidly in response to environmental changes. Since a generation is shorter for bacteria than for multicellular organisms, they genetically adjust more quickly to changes in the holobiont," says Prof. Rosenberg.

Conducting their experiments on the rapidly-reproducing fruit fly, the scientists were able to test this new theory. The first experiment repeated a study carried out two decades ago by a Yale University researcher, in which a fly population was divided in half and fed different diets — malt sugar versus starch. A year later, when the flies were re-integrated as one group, those who had been fed starch preferred starch-fed mates, while the sugar-fed flies preferred mates of a similar nutritional background. The repeat experiment carried out by the Tel Aviv University researchers shows that this dietary influence takes effect within just a generation or two rather than over an entire year.

In their second experiment, the Tel Aviv University team repeated the first, but with the addition of an antibiotic, which killed the bacteria and eliminated the specific mate preference. The mating process became random, with no dietary influence.

In subsequent experiments, the researchers successfully isolated the bacterial species responsible for reproductive isolation in flies with diet-related mating preferences, and found the bacteria Lactobacillus plantarum to be present in greater numbers in starch-fed fruit flies than in sugar-fed flies. When L. plantarum was reintroduced into the antibiotic-treated flies, the preferential mating behavior resumed — proving that this bacterial species is at least partly responsible for the mating preference.

Rewriting Darwin?

Finally, in cooperation with Prof. Avraham Hefetz of Tel Aviv University's Department of Zoology, the team analyzed the sexual pheromones produced by the fruit flies. There turned out to be differences in pheromone levels between the two groups of flies — differences that again disappeared after administering antibiotics.

"The finding indicates that pheromone alterations are a mechanism by which we can identify mating preferences. We therefore hypothesize that it is the bacteria that are driving this change," Prof. Rosenberg says. He adds that these discoveries have implications for our entire understanding of natural selection — something which may even lead to the development of a new theory of evolution.


From the Brain of a Locust ...
11/29/2010

In the human brain, mechanical stress — the amount of pressure applied to a particular area — requires a delicate balance. Just the right force keeps neurons together and functioning as a system within the body, and proper nerve function is dependent on this tension.

Now researchers at Tel Aviv University say that mechanical stress plays an even more important role than medical science previously believed. Their research has the potential to tell us more than ever before about the form and function of neuronal systems, including the human brain. And they've used the common locust to prove it.

Prof. Amir Ayali of Tel Aviv University's Department of Zoology, with Prof. Yael Hanein of the School of Electrical Engineering and Prof. Eshel Ben-Jacob of the Department of Physics, has successfully cultured cells taken from the desert locust to delve deeper into the workings of the mammalian neurosystem. Their most recent discovery, he says, is that mechanical stress plays a pivotal role not only in the development of the brain, but also its function.

Recently published in several journals including Biophysical Journal and Nanotechnology, this research demonstrates that mechanical stress is instrumental in several key phenomena in neuronal development. Once a neuron has developed, explains Prof. Ayali, it is attracted to and then attaches to another neuron, which pulls it to the appropriate place within the neurosystem. "This tension is crucial for making the right connections," he says.

A neuron system in a dish

According to Prof. Ayali, insect cells provide a unique window into the world of neurons because they're easier to work with than human cells. Large enough to culture, Prof. Ayali and his fellow researchers harvested insect neurons and allowed them to regenerate, then built an in vitro nervous system in a dish. The team was then able to follow each single cell optically, watching how they regenerated and recording their electrical activity.

Most importantly, the team was able to observe the neurons form a network. A key feature, Prof. Ayali says, is mechanical tension. As the neurosystem develops, some cells are eliminated, while others are stabilized and preserved. Cells that successfully connect with one another maintain this connection through mechanical stress. This tension draws cells to their destined locations throughout the neurosystem. As neurons develop, they migrate to the appropriate location in the body, and it's mechanical stress that draws them there.

A meeting of the minds

Although the researchers' choice of insect cells for their investigation is unorthodox, Prof. Ayali says that the benefits are tremendous. The cells are basic enough to be applicable to any system, including the human neurosystem, he notes. If it were not for the large size and low density that insect cells provide, the team would not be able to follow individual cells and track the connections they make. "We're looking at simple phenomena that apply generally," he says. "The development from single cells to groups of clusters is common to every kind of neuron."

The research is unique in more ways than one. Prof. Ayali emphasizes that this project exhibits a truly interdisciplinary approach to neuroscience. The project includes researchers from numerous scientific fields, including zoology, electrical engineering and physics.


A Chip Off the Early Hominin Tooth
9/16/2010

Were our early mammalian ancestors vegetarians, vegans or omnivores? It's difficult for anthropologists to determine the diet of early mammalians because current fossil analysis provides too little information. But a new method that measures the size of chips in tooth fossils can help determine the kinds of foods these early humans consumed.

Prof. Herzl Chai of Tel Aviv University's School of Mechanical Engineering, in collaboration with scientists from George Washington University and the U.S. National Institute of Standards and Technology (NIST), has developed an equation for determining how the size of a chip found in the enamel of a tooth relates to the bite force needed to produce the chip. With the aid of this information, researchers can better determine the type of food that animals, and early humans, could have consumed during their lifetimes.

Teeth are the only relevant fossils with staying power, Prof. Chai explains. Made of hard, mineralized material, teeth from animals that are thousands of years old remain relatively intact. Teeth that display a greater number of large chips indicate that animals like our early ancestors were consuming harder foods such as nuts, seeds or items with bones. A lesser amount of small chips  demonstrates that the animal’s diet more likely consisted of softer foods, such as vegetation. Dr. Chai's findings were recently reported in the journal Biology Letters.

Joining anthropology and mechanical engineering

In the recent study, Prof. Chai combined his mechanical engineering background with the expertise of anthropologists at George Washington University and material scientists at NIST to develop a simple equation to predict the maximum bite force used to create a tooth chip. The equation correlates well with a commonly-used equation from jaw mechanics — a more complex approach for determining the maximum bite force an animal can deliver.

Drawn from "fracture mechanics," concerned with the formation of cracks in brittle materials, Prof. Chai's equation takes into account the dimensions of the chip — its distance from the edge of the tooth — and from there solves for the bite force required to have made the chip. The maximum force an animal can apply, notes Prof. Chai, relates to the thickness of the enamel and the size of the tooth itself.

"The bigger the tooth, the bigger area for chips to develop, and therefore, the more force the animal can produce," he says. The team surveyed tooth fossils from many types of mammalians, including six hominins, gorillas and chimpanzees.

We are what we eat

A tooth chip is a permanent signature of consumption, says Prof. Chai. His method demonstrates that the probable food sources of a given animal can be determined from a small number of well-preserved teeth. The fossils used for this particular study were widely available at museums. This is an improvement over previous methods, which relied solely on jaw mechanics and required an almost complete skull to determine eating habits.

This moves researchers one step closer towards grasping the dietary habits of early mammalians. Although the study of tooth chips cannot, thus far, reveal exactly what food produced the chip, it allows researchers to determine a range of foods, providing valuable information about the animal's life that other methods tend to miss.


"Magical Thinking" About Islands Is an Illusion
7/8/2010

Long before TV's campy Fantasy Island, the isolation of island communities has touched an exotic and magical core in us. Darwin's fascination with the Galapagos island chain and the evolution of its plant and animal life is just one example.

Think of the extensive lore surrounding island-bred creatures like Komodo dragons, dwarf elephants, and Hobbit-sized humans. Conventional wisdom has it that they — and a horde of monster-sized insects — are all products of island evolution.

But are they?

Dr. Shai Meiri of Tel Aviv University's Department of Zoology says "yes," they are a product of evolution, but nothing more than one would expect to see by "chance," citing research that shows there's nothing extraordinary about evolutionary processes on islands. He and his colleagues have conducted a number of scientific studies comparing evolutionary patterns of island and mainland ecosystems, and the results refute the idea that islands operate under different, "magical" rules.

Man bites evolutionary dog

"My findings are a bit controversial for some evolutionary biologists," says Dr. Meiri, the author of several papers and essays on island evolution. His research is based on statistical models he developed.

"There is a tendency to believe that big animals become very small on islands, and small animals become very big, due to limited resources or lack of competition. I've shown that this is just not true, at least not as a general rule. Evolution operates on islands no differently than anywhere else."

In a recent study reported in Global Ecology and Biogeography, Dr. Meiri and his colleagues looked at a theoretical optimum body size towards which mammals are expected to grow, on both island communities and on the mainland. "Contemporary evolutionary thinking maintains that smaller island mammals will rapidly grow larger towards the optimal size, while bigger animals will rapidly shrink due to the constraints of competition on the islands. The researchers found that island isolation per se does not really affect the evolutionary rate, the rates of diversification of species, or the rate at which body size shifts in populations of island and mainland animals.

Reality Island?

Employing their own statistical tools incorporating large data sets that compared body sizes on various islands and on mainland communities, Dr. Meiri and his colleagues found no such tendency for bizarrely-sized animals to develop on islands. "We concluded that the evolution of body sizes is as random with respect to 'isolation' as on the rest of the planet. This means that you can expect to find the same sort of patterns on islands and on the mainland."

Dr. Meiri attributes our widely held misperceptions about "dragons and dwarfs" to the fact that people tend to notice the extremes more if they are found on islands.

The reason for science and mankind’s fascination with island communities could boil down to "better press," says Dr. Meiri. If observers investigate human beings on 3,000 different South Pacific islands and all but one of the islands are populated by ordinary-sized people, they will tend to concentrate on the unique case. They forget about the other 2,999 islands in the South Pacific with normal-sized humans, and focus on the unusual.

"I think it's purely a psychological bias," Dr. Meiri concludes. "It's just magical thinking. Nothing more." Fantasies about island habitats and the animals that live there are best left for movies, TV shows, and fantasy novels, he adds.


The Truth About Cats and Dogs
9/8/2008

Thinking about adopting a perky little puppy as a friend for your fluffy cat, but worried that they’ll fight -- well, like cats and dogs?

Think again. New research at Tel Aviv University, the first of its kind in the world, has found a new recipe for success. According to the study, if the cat is adopted before the dog and if they are introduced when still young (less than 6 months for kittens, a year for dogs), there is a high probability that your two pets will get along swimmingly. Results from the research were recently reported in the journal Applied Animal Behaviour Science.

“This is the first time anyone has done scientific research on pets living in the same home,” says Prof. Joseph Terkel, from the Department of Zoology at Tel Aviv University.  “It’s especially relevant to the one-third of Americans who own a pet and are thinking about adopting a second one of the opposite species.”

Talk like a dog

After interviewing almost 200 pet owners who own both a cat and a dog, then videotaping and analyzing the animals’ behavior, TAU researchers concluded that cats and dogs can cohabitate happily if certain conditions are met. Prof. Terkel and his graduate student Neta-li Feuerstein found that two-thirds of the homes they surveyed reported a positive relationship between their cat and dog.

But it wasn’t all sweetness and light (or, for that matter, bones and catnip). There was a reported indifference between the cat and dog in 25% of the homes, while aggression and fighting were observed in 10% of the homes.

One reason for the fighting might have been crossed inter-species signals. Cats and dogs may not have been able to read each other’s body cues. For instance, cats tend to lash their tails about when mad, while dogs growl and arch their backs. A cat purrs when happy, while a dog wags its tail. A cat’s averted head signals aggression, while in a dog the same head position signals submission.

In homes where cat/dog détenteexisted, Prof. Terkel observed a surprising behavior. “We found that cats and dogs are learning how to talk each other’s language. It was a surprise that cats can learn how to talk ‘Dog’ and vice versa.”

What’s especially interesting, Prof. Terkel remarks, is that both cats and dogs have appeared to evolve beyond their instincts. They can learn to read each other’s body signals, suggesting that the two species may have more in common than was previously suspected.

Peacemaking pets can be a model for people

Once familiar with each others’ presence and body language, cats and dogs can play together, greet each other nose-to-nose, and enjoy sleeping together on the couch. They can easily share the same water bowl and in some cases groom each other. The far-reaching implications of this Tel Aviv University research on cats and dogs may extend beyond pets -- to people who don’t get along, including neighbours, colleagues at work, and even world superpowers.

“If cats and dogs can learn to get along,” concludes Prof. Terkel, “surely people have a good chance.”


Humans' Evolutionary Response to Risk Can Be Unnecessarily Dangerous, Finds TAU Study
8/6/2008

The traffic light ahead of you is turning yellow. Do you gun the engine and speed through the intersection, trusting that others will wait for their green, or do you slow down and wait your turn?

That depends more on experience than personality, according to new research from Tel Aviv University. Arnon Lotem, a behavioral ecologist from the Department of Zoology at Tel Aviv University, reports in the prestigious journal Nature that people adopt risk-taking behaviors similar to those of animals like rats and bees. And this behavior, Prof. Lotem and his colleagues say, might not prepare humankind for the modern dangers we face every day -- like crossing the street, accepting a high-risk mortgage, or driving on the freeway.

Lotem believes that our risk-taking behavior had its advantages when we were living as cave-dwellers, but that it poses new and potentially dangerous challenges in our modern technology-driven world.

Feeling risky

"People want to know how people make decisions, whether it's how you drive your car, or whether to invest in a mortgage. It's important to understand when and how we make those decisions, to understand the type of errors people are prone to make," says Prof. Lotem.

"What we have found is that people make decisions based on what option 'appears' to be better most of the time. Under conditions in the natural world this would be the best strategy, but in modern life it has nothing do with the real inherent risks," he adds, citing our individual responses to that yellow light.

People are aware of the actual risks when driving through a light at an intersection, but unless they've already had a brush-with-death or a brush-with-a-traffic-cop, the perceived risk remains low, says Prof. Lotem. This is because in most cases nothing happens to the risk-taker. "You save one minute, but you can lose everything. People don't do the math," he says.

Lotem's study found that, presented with simple decision-making stimuli, people are not analyzing the complete situation based on logical rationales or statistics. Instead, they appear to be making decisions based on simple strategies for coping in nature, based mainly on personal experience.

Evolved to fear cobras, not traffic lights

During many years of evolution and under natural conditions, he says, people made decisions like other animals. This tactic worked fine for survival, but did not however evolve to survive the modern world. "We've evolved to be afraid of snakes, but not traffic lights," he says.

The results of Lotem's research may also be used by economists, politicians and psychologists, who need to know when people will take risks, says Prof. Lotem. A wider understanding of this phenomenon can affect business decisions, the economy -- and, hopefully, the number of road accidents in America each year.

In the business world, Lotem says, "If you give feedback and rewards to employees in a clear way, they might be more willing to take risks on your behalf." He adds that this approach might help governments to cultivate the entrepreneurial activities of their citizens.

Don't gamble on it

But the more complex the risk, the more difficult to predict how people will react. Lotem cautions that in complicated decision-making scenarios such as gambling, addiction and excitement are new variables that come into play. It is also difficult to assess whether children exhibit similar risk-taking strategies as adults, because children tend to imitate what adults around them are doing.

The study's participants also included a team of scientists from the Technion Israel Institute of Technology and The Faculty of Agriculture of the Hebrew University of Jerusalem.


Art in a Petri Dish
12/14/2007

Bacteria are one of the world's most prolific organisms found in every habitat on earth -- in the soil, deep in the earth's crust and even throughout our bodies. The single-celled creatures, which help sustain life, are now painted in a mystifying light by Tel Aviv University's Eshel Ben-Jacob.

Prof. Ben-Jacob, from the School of Physics and Astronomy, has an ongoing laboratory "art" project that illuminates the fairly unknown and complex social behaviors of bacteria. Each of his pictures illustrates the sophisticated colonies that billions of bacteria form. The goal of the project is to unravel the secret lives of bacteria -- the secrets that enable them to survive against all odds.

More information about Prof. Ben Jacob's project, along with many of the resulting artworks, can be found at http://star.tau.ac.il/~eshel/gallery.html.

 


Haifa Home to First Homo Sapiens?
9/10/2007

Although a skeleton of the earliest Homo sapien has not yet been found in the Carmel Caves near Haifa, scientists believe that he may have lived there 250,000 years ago.

What has been found at the sites are modern tools such as flint blades, and evidence of systematic hunting techniques.  These important discoveries may mean that the earliest communities of modern man originated in the Middle East rather than in Africa. 

Professor Israel Hershkotvitz of TAU is co-director of the excavations.

http://www.haaretz.com/hasen/spages/901351.html


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