Tag: Life Sciences

A groundbreaking Tel Aviv University study has discovered about 100,000 new types of previously unknown viruses – a ninefold increase in the amount of RNA viruses known to science until now. The viruses were discovered in global environmental data from soil samples, oceans, lakes, and a variety of other ecosystems. The researchers believe that the discovery may help in the development of anti-microbial drugs and in protecting against agriculturally harmful fungi and parasites.

Most Viruses Not Harmful to Humans

The study was led by doctoral student Uri Neri under the guidance of Prof. Uri Gophna of the Shmunis School of Biomedicine and Cancer Research in The George S. Wise Faculty of Life Sciences at Tel Aviv University. The research was conducted in collaboration with the US-based research bodies NIH and JGI, as well as the Pasteur Institute in France. The study was published in the prestigious journal Cell, and comprised data collected by more than a hundred scientists around the world.

Viruses are genetic parasites, meaning they must infect a living cell to replicate their genetic information, produce new viruses, and complete their infection cycle. Some viruses are disease-causing agents that can cause harm to humans (such as the coronavirus), but most viruses do not harm us – some of them even live inside our bodies without us even being aware of it.

“One of the key questions in microbiology is how and why viruses transfer genes between them. We identified several cases in which such gene exchanges enabled viruses to infect new organisms.” Prof. Uri Gophna

Harnessing Viruses for Use in Medicine and Agriculture

Uri Neri says that the study used new computational technologies to mine genetic information collected from thousands of different sampling points around the world: oceans, soil, sewage, geysers, and more. The researchers developed a sophisticated computational tool that distinguishes between the genetic material of RNA viruses and that of the hosts and used it to analyze the big data. The discovery allowed the researchers to reconstruct how the viruses underwent diverse acclimation processes throughout their evolutionary development to adapt to different hosts.

In analyzing their findings, the researchers were able to identify viruses suspected of infecting various pathogenic microorganisms, thus enabling viruses to control them. “The system we developed makes it possible to perform in-depth evolutionary analyses and to understand how the various RNA viruses have developed throughout evolutionary history,” explains Prof. Gophna. “One of the key questions in microbiology is how and why viruses transfer genes between them. We identified several cases in which such gene exchanges enabled viruses to infect new organisms.”

“Furthermore, compared to DNA viruses, the diversity and roles of RNA viruses in microbial ecosystems are not well understood. In our study, we found that RNA viruses are not uncommon in the evolutionary landscape and, in fact, that in some respects they are not that different from DNA viruses. This opens the door for future research, and for a better understanding of how viruses can be harnessed for use in medicine and agriculture.”

Featured image: The researchers (from left to right): Uri Neri and Prof. Uri Gophna

Every year, wind turbines around the world kill millions of bats and other flying animals that fly into the turbine’s blades. A new study by Tel Aviv University and the University of Haifa offers an original solution to the biological challenge of wind turbine operation and helps prevent harm caused to flying animals, in particular bats: a unique drone-mounted technology that transmits a combination of ultrasonic signals and lights. This deters the bats and leads them to fly at a higher altitude, outside the danger zone, thereby allowing the turbines to continue to operate efficiently and continuously.

“Our study was the first in the world to combine these technologies – RADAR, LIDAR and high-altitude acoustic recorders – to track bats.” Yuval Werber

Innovative Bat Tracking and Signaling

The study was conducted under the leadership of doctoral student Yuval Werber of the Department of Evolutionary and Environmental Biology at the University of Haifa and his two supervisors, Prof. Yossi Yovel, head of Tel Aviv University’s Sagol School of Neuroscience and faculty member of the School of Zoology, and Prof. Nir Sapir, the Head of the Department of Evolutionary and Environmental Biology at the University of Haifa, and in collaboration with the company WinGo Energy and the entrepreneur Gadi Hareli. The article was published in the journal Remote Sensing in Ecology and Conservation, and the study was funded by a research grant from the Israeli Ministry of Energy.

“Wind turbines are considered a promising technology in the field of renewable energy, but their operation involves a variety of biological challenges,” explains Prof. Yossi Yovel. “Today, the only solution to prevent the death of bats is to stop turbine activity at times when the bats are expected to be particularly active. But such interruptions reduce the turbines’ efficiency and the amount of energy they can produce.”

“The advantage of the drone is that it is in constant motion and transmits a combination of visual and acoustic signals designed specifically for bats, warning them of danger. When signals are stationary and constant, animals tend to get used to them and eventually ignore them.”

Yuval Werber shares that, “the study, which is part of my doctoral thesis, was conducted in the Hula Valley, an area with a lot of bat activity. We operated the drone at a height of 100 meters – the average height of the center of a wind turbine, and in motion along a path of about 100 meters, back and forth.”

“To track the bats’ activity, we used RADAR located on the ground, which allowed for tracking at a height of 100 meters and above, and we added a LIDAR device – a laser-based tool that is used to detect objects at short distances, mainly in the automotive industry – for tracking at a lower height. At the same time, we made acoustic recordings of the bats in flight, using receivers placed at three different heights: one meter, 150 meters, and 300 meters. We used a blimp to elevate the receivers. Importantly, our study was the first in the world to combine these technologies – RADAR, LIDAR and high-altitude acoustic recorders – to track bats.”

“On the one hand, it prevents the killing of bats, and on the other hand, it enables the operation of the turbine and the production of green energy in a safe, continuous and efficient manner.” Prof. Yossi Yovel

Effective Bat Repeller

Using a variety of monitoring methods, the researchers compared the bats’ normal activity with their activity in the presence of the drone carrying the deterrent device. The findings were unequivocal – the device succeeded in keeping the bats away. With the drone’s presence, the bats’ activity underneath it decreased by about 40 percent, at a distance of up to about 400 meters. On the other hand, their activity increased above the drone’s altitude of 100 meters, up to 800 meters.

“It appears that the device is effective in repelling bats from its immediate environment – the bats sense the visual and ultrasonic signals it emits and choose to fly over it, as we had hoped,” says Prof. Yovel.

“We hypothesize that if the device is activated near a turbine, it will lead the bats to fly over the turbine and out of harm’s way. This is an effective and easily-implemented solution that is reasonably priced, with great benefit to all parties: on the one hand, it prevents the killing of bats, and on the other hand, it enables the operation of the turbine and the production of green energy in a safe, continuous and efficient manner. We intend to carry out a follow-up experiment on a wind turbine site, in order to test the efficiency of the device under these conditions.”

The phenomenon of marine animals invading distant regions endangers local marine environments and their resident species. A new study from Tel Aviv University included a pioneering experiment simulating the changing environmental conditions encountered en route by marine animals ‘hitching a ride’ by clinging to the bottom of container ships, traveling with the ship to distant regions around the globe. In this study, researchers demonstrate that suitable regulation can decrease this phenomenon and prevent potential invaders from reaching new habitats.

The study was led by research student Doron Bereza under the supervision of Prof. Noa Shenkar of the School of Zoology at the George S. Wise Faculty of Life Sciences and the Steinhardt Museum of Natural History at Tel Aviv University. The paper was published in the prestigious journal Science of the Total Environment. 

“At any given moment, thousands of marine creatures travel from one location to another by marine vessels.”

Harmful to Local Species

The experiment demonstrated that the animals’ ability to survive the arduous journey depends on factors like the type of vessel and the route it navigates, as well as the changing temperature and salinity of seawater.

According to the researchers, the routes of vessels of different sizes are determined mainly by technical limitations of infrastructures at different ports, as well as economic trends in the shipping industry. This results in unique geographic routes that create completely different sets of environmental and other challenges for creatures attaching themselves to these vessels. 

“At any given moment, thousands of marine creatures travel from one location to another by marine vessels,” says Prof. Shenkar. “They do this in two different ways: in the ballast water – seawater taken on by the vessel for stabilizing, or by clinging to the ship’s hull. The problem of invasive species transferred by ballast is addressed by legislation, but the ‘hitchhikers’ clinging to the ships are not – and thus numerous species are transferred from place to place along international trade routes.”

Prof. Noa Shenkar

An experiment conducted by research student Doron Bereza, together with Prof. Shenkar, examined the survivability of two species of ‘ascidians’ [marine invertebrates, or cold-blooded animals with no backbone], known to be harmful, on a journey that follows a typical trade route – from Southeast Asia to Northern Europe. Ascidians attach to hard surfaces such as rocks, breakwaters, and ship hulls. There are hundreds of species of ascidians, and the rise in global trade enables some opportunistic species to disperse over great distances, sometimes establishing themselves as invasive species and harming both marine infrastructures and local species in their new habitats.

Doron Bereza: “We focused on two species of ascidians that are common in the Mediterranean, including Israel, and are known to be transferred by ships. I created a comprehensive database, comprising info from about 200 container ships, and used it to build a route representing the trade routes of two different types of container ships – giant vessels, over 395m in length, vs. ‘regular’ container ships that can be served by the infrastructures of more harbors. In addition, I collected data about changes in seawater temperatures and salinity, as well as chlorophyl concentrations, as a measure for the availability of food on the voyage and at the different ports along the way.”

“We were surprised to discover that one tropical ascidian species survived the entire journey to Rotterdam. This does not mean that the creatures enjoyed their trip, but the fact is that they did survive, and just a few individuals are sufficient for launching an invasive population in the new territory.” 

Making their Trip Unbearable

In the second stage of the study, the researchers exposed both species of ascidians to similar conditions in the lab. Bereza: “We discovered that survivability was significantly impacted by several factors: environmental conditions, the type of vessel, and traits of the animal itself. Under extreme conditions, found in some eastern ports, such as a combination of high temperatures and low salinity, one species died out completely, while no mortality was observed in the other species.”

“In real life, even when routes are generally similar, these ports are not visited by ships over a certain size, for lack of suitable infrastructures. Thus, we concluded that docking at ports with different extremes in conditions can significantly diminish the survival chances of specific species clinging to the ships. Additional experiments of this kind, specifically addressing groups of marine animals that pose a threat, can lead to effective regulatory measures for preventing the conveyance of species.”

Prof. Shenkar adds: “We were surprised to discover that one tropical ascidian species survived the entire journey to Rotterdam. This does not mean that the creatures enjoyed their trip, but the fact is that they did survive, and just a few individuals are sufficient for launching an invasive population in the new territory. Moreover, global warming is expected to enable tropical species to thrive in water that is still too cold at present. The fact that the environmental conditions in some ports on the way proved deadly to almost all members of a certain species, suggests that such locations may be utilized as environmental barriers to prevent the spreading of invasive species.”

Today, when coral reefs around the world are being severely damaged by climate change and other human impacts, many are pinning their hopes on deeper reefs to provide a ’lifeline’ of support for shallow-water coral reefs, which may be more exposed to some hazards. A new Tel Aviv University study, in collaboration with the Interuniversity Institute for Marine Sciences in Eilat, suggests that this hope might have been overestimated.

The findings of the study show that coral spawning events in the Gulf of Aqaba and Eilat, Red Sea, at the deep end of the focal species’ depth range (~30–45 m) occur at much lower intensities than those at shallow water (0–30 m). While in shallow water about half of the corals engaged in each reproductive event, this proportion dropped to only 10–20 percent in the deeper part of the reef.

According to the researchers, the significance of this finding is that there is an insufficient basis for the prevalent hope that deep reefs can serve as a ‘lifeline’ for degraded shallow reefs. In fact, they suggest that for some coral species, the opposite is true—to survive through time, deeper coral populations may more often rely on shallow-reef coral more than vice versa.

The study also demonstrates that sharp increases in water temperature within a day or two affected the onset of the breeding events in the examined species.

The study was led by PhD candidate Ronen Liberman from Tel Aviv University’s School of Zoology and Dr. Tom Shlesinger from Florida Institute of Technology; and supervised by Prof. Yehuda Benayahu of Tel Aviv University’s School of Zoology and Steinhardt Museum of Natural History. Prof. Yossi Loya, also of TAU’s Zoology School and Steinhardt Museum, participated in the study as well. The research was recently published in the prominent journal Ecology, the study partially funded by the European Commission as part of its Horizon 2020 program.

Capturing the Moment

The uniqueness of the study lies within the long-term and intensive examination of coral reproduction throughout a wide depth gradient spanning 0–50 m. The study was conducted over the course of five years to include five breeding seasons. It examined the reproduction of soft corals, also called “Octocorallia,” some of which live throughout a wide depth range in the Gulf of Aqaba and Eilat. Specifically, the researchers focused on a species of a soft coral, called Rhytisma fulvum, which reproduces by “surface-brooding”—a reproductive mode by which the coral brood, or hatch, their strikingly yellow larvae glued externally to the coral surface for several days. This unique reproductive mode helps scientists overcome many of the difficulties in examining and monitoring coral reproductive events, especially in the more challenging-to-work depths.

Ronen Liberman explains: “Most coral species are hermaphrodites, meaning that each individual functions as both male and female, and they reproduce by brief and synchronous spawning events, which usually occur once a year in the summer months. During this synchronized event, many corals simultaneously release a huge amount of sperm and eggs which meet externally in the water, where they undergo fertilization and form embryos. In other species, male corals release sperm into the water, and these cells migrate into female corals and fertilize the eggs internally, so that fertilization and embryonic development occurs within the coral. In both cases, the event lasts only a few minutes, mostly at night, so it is very difficult for researchers to ‘capture the moment,’ especially at great depths where divers cannot remain for a long time. Therefore, very little is known about coral reproduction at depths greater than approximately 15 m.”

A Colorful Event

In the present study, the researchers focused on the soft coral Rhytisma fulvum which lives in the Gulf of Eilat and Aqaba along a large depth range: from reef flats close to the sea surface and down to 50m. A particular reason for the choice of this species is its unique reproductive strategy, called “surface-brooding”. This reproductive process begins when male colonies release sperm cells in a synchronized manner, which later reach female colonies where internal fertilization occurs.

Unlike in other coral species, however, in this species, embryos do not proceed to develop internally within the coral. Instead, the fertilized eggs are released and cling to the colony via mucus for six days, where they develop into larvae. “The developing embryos have such a vibrant yellow color that makes it a very colorful event, lasting for several days. Thanks to that fact, we were able to monitor rather easily a large number of colonies along a large depth range throughout five annual reproductive seasons,” says Ronen.

Trying to create their own sunshine? (Photo: Tom Shlesinger)

Corals Like it Hot

The researchers dove to various depths, positioned temperature sensors, and examined several characteristics of the breeding events–timing, duration, and intensity of the events.

They sought to understand which environmental factors influence the onset of reproductive events:

The study showed that the timing and synchronization of reproduction events, at any given depth are associated with a clear and fast increase in water temperature of 1–1.5 degrees Celsius within 24-48 hours – a kind of a “heat wave” that is typical in the waters of the Gulf of Aqaba and Eilat in early summer. In shallow water (approx. 5-15 m), the reproductive events always occurred days to weeks before they were observed at the greater depths. The researchers attributed this phenomenon to the short-term “heat waves” in the deeper water usually occurred only several days to weeks after they occurred in the shallow water.

The reproductive intensity was measured by the number of colonies that reproduced and released embryos at each event. “We found that the number of colonies releasing embryos was significantly smaller at a depth greater than 30 meters,” Ronen adds. “Whereas at a shallow depth, about half of the colonies participated in each spawning event, in the deeper water the participation rate dropped to only 10–20 percent.”

Considering these findings, the researchers believe that the deep-water coral populations are less likely to thrive on their own and are reliant to some extent on populations from the shallower reef. Because of their lower breeding intensity, it appears that the deep-water coral population requires the contribution of the larvae from the corals found in the shallower water. The researchers suggest that this ‘weakness’ among the deep corals may be linked to the much lower intensity of sunlight that reaches their habitat. Sunlight is necessary for photosynthesis, in which symbiotic algae found within the coral tissue convert light energy to provide the coral host with the chemical energy it needs.

Protecting those at High Risk

The researchers conclude: “Today, when coral reefs around the world are being severely damaged by climate change and other human impacts, many are pinning their hopes on deeper reefs to provide a ’lifeline’ of support for shallow-water coral reefs, which may be more exposed to some hazards. While we do not wish to diminish the optimism, our research suggests that this hope might have been overestimated. Rather, it looks like it is the deeper coral populations that need the shallow ones to persist more than vice versa. Therefore, these hidden deep reefs require attention and protection on their own right, perhaps even more than the shallow reefs.”

Wheat supplies about one fifth of all calories and proteins consumed by humanity. However, through the millennia, the process of cultivation has reduced the diversity of wheat varieties, and consequently modern wheat varieties are more vulnerable than their predecessors to diseases, pests, and climate hazards. The escalating climate crisis creates an urgent need to produce wheat varieties capable of thriving in extreme environmental and climatic conditions and withstanding pests and diseases.

An international research team that includes researchers from Tel Aviv University has isolated three disease-resistance genes from wild grasses, enabling resistance to rust diseases that cause severe damage to wheat yields worldwide.

It’s in The Genes

The project was facilitated by several technological innovations that drastically cut down the time needed to identify and isolate genes from wild plant species and transfer them into cultivated plants.

“Since wheat first originated in our part of the world, wild cereals growing in our region are the progenitors of cultivated wheat, still carrying a rich variety of genetic traits that can be used to develop improved wheat varieties.”

The three genes were isolated from plants preserved in the Liberman Okinow Gene Bank of Wild Cereals at the Institute for Cereal Crops Research (ICCR) at the George S. Wise Faculty of Life Sciences at Tel Aviv University. Two of the genes, providing immunity against stem rust disease, were isolated by an international team led by researchers from the UK. The third gene, isolated by researchers at TAU, provides resistance against two different diseases – leaf rust and stripe rust, currently exacerbated due to rising temperatures around the world.

Prof. Amir Sharon, Head of ICCR, says that isolating the genes was enabled by several technological breakthroughs, and that these novel technologies can also be used to isolate genes for other beneficial properties. Transferred into the genome of cultivated wheat, such genes will serve to generate better wheat varieties – featuring higher yields, and resistant to diseases, pests, and harsh environmental conditions. “Just as each of us carries only a small part of his/her grandparents’ genes, cultivated wheat contains only a remnant of its ancient ancestors’ genetic heritage. Since wheat first originated in our part of the world, wild cereals growing in our region are the progenitors of cultivated wheat, still carrying a rich variety of genetic traits that can be used to develop improved wheat varieties,” explains Prof. Sharon.

“Certain traits of wild plants have already been incorporated into cultivated wheat over the years, however this great genetic potential remained mostly untapped, since, until recently, it took more than a decade to isolate a single gene. Today, thanks to several technological breakthroughs, especially genome sequencing and bioinformatics, we can isolate new genes in less than a year. Thus, in the past year alone, three genes providing resistance to various rust diseases were isolated from seeds of wild plants preserved in our gene bank. These genes, implanted in cultivated wheat, can significantly reduce damage from the relevant diseases with no need for pesticides – preventing yield losses while also protecting the environment.”

In addition to disease resistance, Prof. Sharon’s team is collaborating with researchers worldwide to isolate genes for other beneficial traits. Thus, for example, they work with researchers from Ben-Gurion University who recently isolated pest-resistance genes from wild wheat, and in our own Institute they’ve identified a new gene in wheat progenitors, that may provide endurance in an arid climate.

Prof. Amir Sharon & Dr. Arava Shatil Cohen in the lab

‘Safe Box’ to Tackle Climate Change

In addition to new methods for isolating genes, great advances have been made in biotechnology, specifically in technologies for gene transfer and genome editing. These technologies enable the transfer of new genes to crop plants, as well as introduction of changes into existing wheat genes.

“Essentially, the collection serves as a safe box for genes needed to create new, improved varieties of wheat that will give humanity larger crops and meet the challenges of climate change.”

ICCR implements these new technologies, offering services of wheat gene transformation and genome editing to researchers in other institutes, as well as commercial companies. “With the support of the Chief Scientist of Israel’s Ministry of Agriculture, and the Israeli Center for Genome Editing in Agriculture, we have established a center for wheat transformation and genome editing at ICCR,” shares Prof. Sharon. “This is an important milestone, enabling us, for the first time, to perform effective wheat transformation here in Israel,” says Prof. Sharon.

Dr. Arava Shatil Cohen, Head of the wheat transformation unit, adds: “With these technologies we can implant new genes and use genome editing methods to give wheat new properties. We utilize our systems to promote research at ICCR and help companies and researchers from other institutions who wish to use this technology”.

Today, ICCR’s gene bank includes over 17,000 seeds of 20 different species of wild cereals, collected in Israel over the past 50 years. The collection is unique, both because of its large number of species related to cultivated wheat, and because a large portion of the plants preserved in the gene bank were collected in natural habitats that no longer exist due to rapid urban development in Israel. “Essentially, the collection serves as a safe box for genes needed to create new, improved varieties of wheat that will give humanity larger crops and meet the challenges of climate change,” says Prof. Sharon. “The new technologies are the key to the safe box: they enable us to identify and extract the needed genes quickly and incorporate them into cultivated wheat.”