Tag: Life Sciences

Are Corals in Deep Trouble?

Reproductive capacity of coral decreases with water depth.

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.”

Featured image: Life at the bottom (Photo: Jessica Bellworthy)

Making Wheat Rust-Resistant

Researchers respond to the global food crisis by enabling resistance of wheat to rust diseases.

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.”

Like Manna from the Sea

Innovative technology may ease global food crisis: “enriched seaweed” with extremely high nutritional value.

Researchers from Tel Aviv University and the Israel Oceanographic and Limnological Research Institute in Haifa have developed an innovative technology that enables the growth of “enriched seaweed” infused with nutrients, proteins, dietary fiber, and minerals for human and animal needs.


According to the researchers, the state-of-the-art technology significantly increases the growth rate, protein levels, healthy carbohydrates, and minerals in the seaweed’s tissues – making the “enriched seaweed” a natural superfood with extremely high nutritional value, which can be used in the future for the health food industry and to secure an unlimited food source.


The research was led by Ph.D. student Doron Ashkenazi, under the guidance of Prof. Avigdor Abelson from the School of Zoology, George S. Wise Faculty of Life Sciences at Tel Aviv University and Prof. Alvaro Israel of the Israel Oceanographic and Limnological Research Institute (IOLR) in Tel Shikmona, Haifa. The article was published in the scientific journal Innovative Food Science & Emerging Technologies.


“Seaweed can be regarded as a natural superfood, more abundant in the necessary components of the human diet than other food sources.”



A Natural Superfood

Doron Ashkenazi explains that in the study, local species of the algae Ulva, Gracilaria and Hypnea were grown near fish farming systems under different environmental conditions. The special conditions allowed the seaweed to flourish and enabled a significant improvement in their nutritional value ​​to the point of their becoming “enriched seaweed,” a superfood.


“Seaweed can be regarded as a natural superfood, more abundant in the necessary components of the human diet than other food sources,” Ashkenazi adds. “Through the technological approach we developed, a farm owner or entrepreneur will be able to plan in advance a production line of seaweed rich in the substances in which they are interested, which can be used as health foods or nutritional supplements; for example, seaweed with a particularly high level of protein, seaweed rich in minerals such as iron, iodine, calcium, magnesium, and zinc, or in special pigments or anti-oxidants. The enriched seaweed can be used to help populations suffering from malnutrition and nutritional deficiencies, for example disadvantaged populations around the world, as well as supplements to a vegetarian or vegan diet.”


In fact, the use of seaweed as a rich food source that meets all human nutritional needs is reminiscent of the biblical manna that fed the Israelites in the desert.


Layout of the land-based, outdoor, aquaculture system as was stationed at the IOLR institute, Haifa, Israel


“Technologies of this type are undoubtedly a model for a better future for humanity, a future where humans live in idyll and in health in their environment.”


Aquaculture, Tomorrow’s Agriculture

Unlike terrestrial agriculture, aquaculture, and in particular the proposed seaweed farming approach, does not require extensive land, fresh water, or large amounts of fertilizer. Environmentally friendly, it preserves nature and the ecological balance by reducing environmental risks. The new methodology, in fact, offers an ideal situation, of sustainable and clean agriculture.


Today, integrated aquaculture is beginning to receive support from governments around the world due to its environmental benefits, which include the reduction of nutrient loads to coastal waters and of the emission of gases and carbon footprints. In this way, it contributes to combatting the climate crisis and global warming.


“Technologies of this type are undoubtedly a model for a better future for humanity, a future where humans live in idyll and in health in their environment,” concludes Ashkenazi.


The research was conducted in collaboration with other leading researchers from around the country, including Guy Paz and Dr. Yael Segal of the Israel Oceanographic and Limnological Research Institute (IOLR) in Haifa, Dr. Shoshana Ben-Valid, an expert in organic chemistry, Dr. Merav Nadav Tsubery of the Department of Chemistry in the Faculty of Exact Sciences at Bar-Ilan University, and Dr. Eitan Salomon from the National Center for Mariculture in Eilat.

Stop Blaming the Bats for Covid-19

Researchers conclude there’s insufficient proof of correlation between bats and the outbreak of the epidemic.

Shortly after outbreak of the Corona epidemic, accusations were voiced among the public, as well as within the scientific community, claiming that the bats are considered a health threat, as reservoirs of viruses’, including the Covid-19 virus. A new Tel Aviv University study rejects this correlation between the Covid-19 outbreak and bats, which the researchers say was not based on sufficient compelling scientific proof. Bats have a highly effective immune system that enables them to deal relatively easily with viruses that are considered lethal for other mammals.

Bats with a Bad Rap

The study was led by Dr. Maya Weinberg from the laboratory of Prof. Yossi Yovel, Head of the Sagol School of Neuroscience and faculty member of the School of Zoology and the Steinhardt Museum of Natural History at Tel Aviv University. The research team reviewed dozens of leading articles and studies in this field, and their conclusions were published in writing in the prestigious iScience Journal.

The researchers explain that the infamous reputation of the bats is well known among both the scientific community and the public at large, namely that they are often accused of being reservoirs of viruses including Covid-19, thus posing a threat to public health. While there is indeed evidence that the origin of the “ancient potential” Covid-19 was in bats, the researchers note that two years after the pandemic first broke out, we still do not know for sure what the exact origin of the COVID-19 variant is.


“Bats have a highly effective immune system that enables them to deal relatively easily with viruses considered lethal for other mammals.”


Dr. Weinberg: “In general, bats are mistakenly conceived of as reservoirs of many contagious disease, only due to their being positive serologically positive; in other words, in possession of antibodies, which means that bats have survived the disease and developed an immune response. After that, they overcame the virus altogether and disengaged from it; hence, they are no longer its carriers. Nevertheless, in many cases, a virus similar to a human pathogen is liable to be found in bats; however, it is not pathogenic to humans, and is not sufficient to use bats as a reservoir.”


Dr. Weinberg with a friend

Capable of Coping with Different Viruses

To examine the overall situation, the researchers conducted a meta-analysis of literature on over 100 viruses for which bats are considered potential reservoirs, including Ebola, SARS, and COVID. “We found that in a considerable number of cases (48%) this claim was based on the incidence of antibodies or PCR tests, rather than actual isolation of identical viruses. Moreover, many of the reported findings are not convincing,” says Dr. Weinberg.

“The mere isolation of a virus is not enough to see an animal as a reservoir, since a minimum number of index cases is required in which the virus is isolated in order to be considered a reservoir animal, as well as the existence of an established path of transmission. Furthermore, the very detection of a particular virus in bats does not necessarily ensure further infection. Additional biological, ecological, and anthropogenic conditions must exist for such an event to occur.”

According to the researchers, simultaneously, in recent years evidence is accumulating of the fact that bats are capable of coping with different viruses, including lethal ones, better than humans and most other mammals. After over 100 years of focus on viruses carried by bats, it appears that bats’ immune system is characterized by a restrained response during inflammatory processes. As we see it, bats have developed an excellent balance between resistance and tolerance: an increased defense response of the host, and immune tolerance through a number of different mechanisms. Moderate inflammatory pathways contribute to immune tolerance with bats, and a well-balanced response that prevents the virus from developing.


“The comprehensive study we’ve conducted raises serious doubts regarding the possibility of bats being the origin of the Covid19 outbreak. The findings give rise to the opposite perspective, according to which we must study in-depth the immunological anti-viral capabilities of bats, and thus obtain new and effective means of coping in humanity’s struggle against contagious disease, aging, and cancer,” concludes Dr. Weinberg.

Featured image: Wouldn’t hurt a fly? (Photo: Yuval Barkai)

Eradicating Deadly Brain Tumors by ‘Starvation’

A groundbreaking study at Tel Aviv University effectively eradicated glioblastoma, a highly lethal type of brain cancer. The researchers achieved the dramatic outcome using a method they developed based on their discovery of two critical mechanisms in the brain that support tumor growth and survival: one protects cancer cells from the immune system, while the other supplies the energy required for rapid tumor growth. The researchers found that both mechanisms are controlled by brain cells called astrocytes, and in their absence, the tumor cells die and are eliminated.

The study was led by Ph.D. student Rita Perelroizen, under the supervision of Dr. Lior Mayo of the Shmunis School of Biomedicine and Cancer Research and the Sagol School of Neuroscience, in collaboration with Prof. Eytan Ruppin of the National Institutes of Health (NIH) in the USA. The paper was published in the scientific journal Brain and was highlighted with special commentary.

Focusing on Tumor Environment

The researchers explain: “Glioblastoma is an extremely aggressive and invasive brain cancer, for which there exists no known effective treatment. The tumor cells are highly resistant to all known therapies, and, sadly, patient life expectancy has not increased significantly in the last 50 years. Our findings provide a promising basis for the development of effective medications for treating glioblastoma and other types of brain tumors.”

“We tackled the challenge of glioblastoma from a new angle,” explains Dr. Mayo. “Instead of focusing on the tumor, we focused on its supportive microenvironment, that is, the tissue that surrounds the tumor cells.”


“In the absence of astrocytes, the tumor quickly disappeared, and in most cases, there was no relapse – indicating that the astrocytes are essential to tumor progression and survival.”

“Specifically, we studied astrocytes – a major class of brain cells that support normal brain function, discovered about 200 years ago and named for their starlike shape. Over the past decade, research from us and others revealed additional astrocyte functions that either alleviate or aggravate various brain diseases. Under the microscope we found that activated astrocytes surrounded glioblastoma tumors. Based on this observation, we set out to investigate the role of astrocytes in glioblastoma tumor growth.”

Using a lab model, in which they could eliminate active astrocytes around the tumor, the researchers found that in the presence of astrocytes, the cancer killed all lab models with glioblastoma tumors within 4-5 weeks. Applying a unique method to specifically eradicate the astrocytes near the tumor, they observed a dramatic outcome: the cancer disappeared within days, and all treated lab models survived. Moreover, even after discontinuing treatment, most of the lab models survived.

WATCH: Dr. Lior Mayo explains the dramatic breakthrough in addressing glioblastoma, a deadly brain cancer


Exposing Mechanisms of Double Agents

“In the absence of astrocytes, the tumor quickly disappeared, and in most cases, there was no relapse – indicating that the astrocytes are essential to tumor progression and survival,” notes Dr. Mayo. “Therefore, we investigated the underlying mechanisms: How do astrocytes transform from cells that support normal brain activity into cells that support malignant tumor growth?”

To answer these questions, the researchers compared the gene expression of astrocytes isolated from healthy brains and from glioblastoma tumors. They found two main differences – thereby identifying the changes that astrocytes undergo when exposed to glioblastoma:

  1. The first change was in the immune response to glioblastoma. Dr. Mayo clarifies, “The tumor mass includes up to 40% immune cells – mostly macrophages recruited from the blood or from the brain itself. Furthermore, astrocytes can send signals that summon immune cells to places in the brain that need protection. In this study, we found that astrocytes continue to fulfill this role in the presence of glioblastoma tumors. However, once the summoned immune cells reach the tumor, the astrocytes ‘persuade’ them to ‘change sides’ and support the tumor instead of attacking it. Specifically, we found that the astrocytes change the ability of recruited immune cells to attack the tumor both directly and indirectly – thereby protecting the tumor and facilitating its growth.”
  2. The second change through which astrocytes support glioblastoma is by modulating their access to energy – via the production and transfer of cholesterol to the tumor cells. The malignant glioblastoma cells divide rapidly, a process that demands a great deal of energy. With access to energy sources in the blood barred by the blood-brain barrier, they must obtain this energy from the cholesterol produced in the brain itself – namely in the astrocytes’ ‘cholesterol factory’, which usually supplies energy to neurons and other brain cells. “We discovered that the astrocytes surrounding the tumor increase the production of cholesterol and supply it to the cancer cells,” explains Dr. Mayo. “Therefore, we hypothesized that, because the tumor depends on this cholesterol as its main source of energy, eliminating this supply will starve the tumor.”

The Tumor’s Vulnerability, a Therapeutic Opportunity

Next, the researchers engineered the astrocytes near the tumor to stop expressing a specific protein that transports cholesterol (ABCA1), thereby preventing them from releasing cholesterol into the tumor. Once again, the results were dramatic: with no access to the cholesterol produced by astrocytes, the tumor essentially ‘starved’ to death in just a few days. These remarkable results were obtained in both lab models and glioblastoma samples taken from human patients and are consistent with the researchers’ starvation hypothesis.


“The challenge now, is to develop drugs that target the specific processes in the astrocytes that promote tumor growth. Alternately, existing drugs may be repurposed to inhibit mechanisms identified in this study.”


Dr. Mayo notes: “This work sheds new light on the role of the blood-brain barrier in treating brain diseases. The normal purpose of this barrier is to protect the brain by preventing the passage of substances from the blood to the brain. But in the event of a brain disease, this barrier makes it challenging to deliver medications to the brain and is considered an obstacle to treatment. Our findings suggest that, at least in the specific case of glioblastoma, the blood-brain barrier may be beneficial to future treatments, as it generates a unique vulnerability – the tumor’s dependence on brain-produced cholesterol. We think this weakness can translate into a unique therapeutic opportunity.”

The project also examined databases from hundreds of human glioblastoma patients and correlated them with the results described above. The researchers explain: “For each patient, we examined the expression levels of genes that either neutralize the immune response or provide the tumor with a cholesterol-based energy supply. We found that patients with low expression of these identified genes lived longer, thus supporting the concept that the genes and processes identified are important to the survival of glioblastoma patients.”

“Currently, tools to eliminate the astrocytes surrounding the tumor are available in lab models, but not in humans,” notes Dr. Mayo. “The challenge now, is to develop drugs that target the specific processes in the astrocytes that promote tumor growth. Alternately, existing drugs may be repurposed to inhibit mechanisms identified in this study. We think that the conceptual breakthroughs provided by this study will accelerate success in the fight against glioblastoma. We hope that our findings will serve as a basis for the development of effective treatments for this deadly brain cancer and other types of brain tumors,” he concludes.

Two New Planets Found in Milky Way

TAU team leads discovery of giant planets, similar in size to Jupiter, in remote corner of the galaxy.

Tel Aviv University researchers led the recent discovery of two new planets in remote solar systems within the Milky Way galaxy. They identified the giant planets, named Gaia-1b and Gaia-2b, as part of a study in collaboration with teams from the European Space Agency (ESA) and the body’s Gaia spacecraft.

The development marks the first time that the Gaia spacecraft successfully detected new planets. Gaia is a star-surveying satellite on a mission to chart a 3D map of the Milky Way with unprecedented accuracy comparable to standing on Earth and identifying a 10-shekel coin (roughly the size of a U.S. nickel) on the Moon.  

TAU’s Prof. Shay Zucker, Head of the Porter School of the Environment and Earth Sciences, and doctoral student Aviad Panhi from the Raymond and Beverly Sackler School of Physics & Astronomy led the initiative. The findings were published in the scientific journal Astronomy & Astrophysics. 

More Discoveries on the Horizon

“The discovery of the two new planets was made in the wake of precise searches, using methods of artificial intelligence,” said Prof. Zucker. “We have also published 40 more candidates we detected by Gaia. The astronomical community will now have to try to corroborate their planetary nature, like we did for the first two candidates.”

The two new planets are referred to as “Hot Jupiters” due to their size and proximity to their host star: “The measurements we made with the telescope in the U.S. confirmed that these were in fact two giant planets, similar in size to the planet Jupiter in our solar system, and located so close to their suns that they complete an orbit in less than four days, meaning that each Earth year is comparable to 90 years of that planet,” he adds.  

Giant Leaps for Astronomy 

There are eight planets in our solar system. Less known are the hundreds of thousands of other planets in the Milky Way, which contains an untold number of solar systems. Planets in remote solar systems were first discovered in 1995 and have been an ongoing subject of astronomers’ research ever since, in hopes of using them to learn more about our own solar system.  

To fulfill its mission, Gaia scans the skies while rotating around an axis, tracking the locations of about 2 billion suns, stars at the center of a solar system, in our galaxy with precision of up to a millionth of a degree. While tracking the location of the stars, Gaia also measures their brightness — an incomparably important feature in observational astronomy, since it relays significant information about the physical characteristics of celestial bodies around them. Changes documented in the brightness of the two remote stars were what led to the discovery. Aviad Panhi explains: “The planets were discovered thanks to the fact that they partially hide their suns every time they complete an orbit, and thus cause a cyclical drop in the intensity of the light reaching us from that distant sun.”

To confirm that the celestial bodies were in fact planets, the researchers performed tracking measurements with the Large Binocular Telescope, in Arizona, one of the largest telescopes in the world today. The telescope makes it possible to track small fluctuations in a star’s movement which are caused by the presence of an orbiting planet.

The discovery marks another milestone in the scientific contribution of the Gaia spacecraft’s mission, which has already been credited with a true revolution in the world of astronomy. Gaia’s ability to discover planets via the partial occultation method, which generally requires continuous monitoring over a long period of time, has been doubted up to now. The research team charged with this mission developed an algorithm specially adapted to Gaia’s characteristics, and searched for years for these signals in the cumulative databases from the spaceship.  

Signs of Life?

What about the possibility of life on the surface of those remote new planets? “The new planets are very close to their suns, and therefore the temperature there is extremely high, about 1,000 degrees Celsius, so there is zero chance of life developing there,” explains Panhi. Still, he says, “I’m convinced that there are countless others that do have life on them, and it’s reasonable to assume that in the next few years we will discover signs of organic molecules in the atmospheres of remote planets. Most likely we will not get to visit those distant worlds any time soon, but we’re just starting the journey, and it’s very exciting to be part of the search.” 

Diagnosing Diseases in Space

TAU researchers successfully test genetic diagnosis under microgravity conditions.

If pursuing the unknown in space is on your bucket list, you can take comfort in knowing that TAU researchers recently conducted a unique experiment at the International Space Station to test genetic diagnosis under microgravity conditions. The researchers launched a kit together with Israeli astronaut Eytan Stibbe to space and proved that an existing technology based on a bacterial immune system against viruses, ‘CRISPR’, can be used to identify viruses and bacteria infecting crew members during space missions.

The study was led by Dr. Dudu Burstein from the Shmunis School of Biomedicine and Cancer Research, Tel Aviv University and Dr. Gur Pines from the Volcani Institute. The experiment was conducted by Stibbe as part of the “Rakia” mission in April, under the leadership of the Ramon Foundation and the Israel Space Agency.

Suited for Astronauts

CRISPR systems are the immune systems of bacteria from viruses. Bacteria use the CRISPR-Cas systems as a sort of molecular ‘search engine’ to locate viral sequences and cleave them to disable viruses.

As part of their scientific vision, the researchers hypothesized that genetic diagnostics using this method, which requires minimal and easily operated equipment, could be suitable for long space missions: “Conditions in space are extremely problematic,” explains Burstein. “Treatment methods are limited, so it is essential to identify pathogens [= a microorganism that can cause disease] in a rapid, reliable, and straightforward method.” The method stands in contrast to tests like PCR (which we are now all familiar with due to Covid-19), which Burstein notes require trained personnel and relatively complex equipment.”


Researchers discussing the experimental design. From left to right: Dan Alon, Dr. David Burstein, Dr. Gur Pines (Photo: Ella Rannon)

Burstein outlines the process: “First, the DNA is amplified: each targeted DNA molecule is repeatedly duplicated many times. Then the CRISPR-Cas goes into action: If it identifies the target DNA, it activates a fluorescent molecular marker. The fluorescence lets us know whether the bacteria or viruses of interest are indeed present in the sample. This whole process can be conducted in one tiny test tube, so it is well suited for the astronauts’ needs.”

Zero Gravity? No problem!

Dr. Burstein describes the preparation for the space experiment: “Doctoral student Dan Alon and Dr. Karin Mittelman planned the experiment in detail and conducted it countless times in the lab under various conditions. After reaching the desired result, they prepared a kit, including the CRISPR-Cas system and the other components required for detection. Eventually, the kit was launched with Eytan Stibbe to the International Space Station.”

The experiments conducted by Stibbe were very successful, and proved that it is indeed possible to perform precise and sensitive CRISPR-based diagnosis – even in an environment with virtually no gravity.

What now? “This is the first step towards the simple and rapid diagnosis of diseases and pathogens on space missions,” says Burstein, adding that there is still some work to do on the next stages, including, “simple extraction of DNA from samples, making the system more efficient, so that it will be able to test a variety of organisms in one test tube, and diagnosis of more complex samples.”

“It was inspiring to see our test kit in Eytan’s hands at the Space Station, and we’re even more excited by the possibility that such kits will help future astronauts on their extraterrestrial missions,” he concludes.


Eytan Stibbe executing the experiment on the International Space Station (Photo: the Ramon Foundation and the Israel Space Agency)

Featured image: International space station on orbit of planet Earth 

If We Let Them Go, They Won’t Come Crawling Back

One in every five species of reptiles is facing extinction.

There are over 12,000 species of reptiles crawling our planet, but according to a new international study, involving researchers from Tel Aviv University and Ben-Gurion University of the Negev, 21% of these, or a total of about 2,000 species, are threatened with extinction. How can we save them? Or is it too late?

15.6B Years of Evolution Down the Drain?

The comprehensive study, the first of its kind in history, was conducted by the International Union for Conservation of Nature (IUCN) and included 52 researchers from around the world, including Prof. Shai Meiri of Tel Aviv University’s School of Zoology, The George S. Wise Faculty of Life Sciences and the Steinhardt Museum of Natural History, and Dr. Uri Roll of Ben-Gurion University of the Negev. The study was published in the prestigious journal Nature.

The findings of the study show that 30% of forest-dwelling reptiles and about 14% of those living in arid areas are threatened, and that 58% of all turtle species and 50% of all crocodile species are in danger of becoming extinct. The researchers sadly point out that if all of the 1,829 species of turtles, crocodiles, lizards, and snakes that have been found to be threatened do indeed become extinct in the coming years, the world will lose a cumulative wealth of 15.6 billion years of evolution.

Fortunately, no species of reptile has become extinct in Israel in the last decade, but there are many species that are endangered, such as the Hermon Gecko, the Be’er Sheva fringe-fingered lizard and several more.


50% of all crocodile species are in danger of becoming extinct

Mapping Out the Threats

The IUCN is an international body whose role is, among other things, to assess the threat of extinction posed to various species. Each species of animal or plant receives a score on a five-point scale. The purpose of this ranking is to define those species that are the most endangered, thereby enabling decision makers and various bodies, such the Israel Nature and Parks Authority, to outline policies accordingly.

In 2004, the IUCN released a comprehensive report on amphibians, and a few years later it issued reports on birds and mammals. The IUCN has been working on the reptile report for the past 18 years, having invited experts on this taxonomic group from all over the world to participate.

“In general, the state of reptiles in the world is bad,” says Prof. Meiri. “It’s worse than that of birds and mammals, though not as bad as that of the amphibians. And of course there are a lot of nuances. We see that turtles are in a worse position than lizards and snakes, but that may be because we know more about turtles. Perhaps if we knew more about snakes, we would see that they, too, are in big trouble.”

“The biggest threat to reptiles is the destruction of their habitats due to agriculture, deforestation, and urban development, and less because of direct hunting, which mainly affects turtles and crocodiles. We created detailed maps of these threats. For example, if a particular species is highly threatened in the Israel’s Arava desert, but not in the rest of its habitat range that may span the entire Arabian Peninsula, then globally it is not considered a threatened species. The new assessments, for more than 10,000 species of reptiles, will allow us to understand their conservation needs, and hopefully enable us to find far more intelligent solutions for them than we have been able to so far.”


Prof. Shai Meiri

Dr. Uri Roll adds, “This is important work that forms the initial basis for risk assessment among various reptiles around the world, but is certainly not the end of the story. We still lack a lot of information about the various risks facing reptiles. For example, climate change is expected to have significant effects on reptiles. The current assessment that has just been published does not yet include these future threats in its reptile risk assessments. We still have a lot of work ahead of us.”

When asked whether it is still possible to stop the wheels from turning, Prof. Meiri says that “There’s room for optimism, but not overly so. It is finally possible, thanks in part to this study, to plan dedicated nature conservations for reptiles as well – there is more awareness and there are ways in which we can help them. In Israel, great efforts are made to protect various kinds of turtles. Less attention is paid to most species of lizards and snakes, however, which make up the vast majority.”

Featured image: Endangered: Egyptian mastigure (Photo: Alex slavenko)

The Ultimate Solution to Global Warming?

Breakthrough TAU discovery may accelerate an industrial transition to sustainable energy.

Hydrogen-powered bicycles and cars have been in serial production for years. In these vehicles, the regular polluting lithium battery has been replaced by a fuel cell that converts hydrogen, a non-polluting fuel, to electricity. Most of today’s hydrogen is, however, still produced from natural gas in a highly polluting process and is therefore referred to as gray hydrogen. Not only is natural gas a non-renewable source of energy, but it also creates carbon dioxide gas when burned, damaging our environment and contributing to global warming.

Enter a new TAU discovery, which may boost the industrial transition from using polluting gray hydrogen to environmentally friendly green hydrogen: Researchers identified a mutant of a known strain of microscopic algae that allows, for the first time, the production of green hydrogen gas via photosynthesis on a scale suited to industrial requirements. Hydrogen gas can thus be produced solely through renewable energy and in a climate-neutral manner, reducing our carbon footprint and greenhouse gas emissions dramatically to stabilize global temperatures. 

Humanity’s transition to the use of green hydrogen may be the ultimate solution to the problem of global warming.

The microscopic algae

Continuous Production Achieved

The study was led by doctoral student Tamar Elman, under the supervision of Prof. Iftach Yacoby from the Renewable Energy Laboratory of The George S. Wise Faculty of Life Sciences at Tel Aviv University. The study was recently published in the prestigious journal Cell Reports Physical Science

While production of green hydrogen is possible through solar panels wired to devices that perform water breakdown into hydrogen and oxygen (electrolysers), the researchers explain that this is an expensive process, requiring precious metals and distilled water. In nature, hydrogen is produced as a by-product of photosynthesis for periods of minutes by micro-algae, unicellular algae found in every water reservoir and even in the soil. For this biological process to become a sustainable source of energy, however, humanity must engineer micro-algae strains that produce hydrogen for days and weeks.

Prof. Yacoby explains that as part of the laboratory tests, the researchers identified a new mutant in microscopic algae that prevents oxygen from accumulating at any lighting intensity, and therefore hypothesized that continuous hydrogen production could be achieved from it. With the help of bioreactor measurements in liter volumes, they were indeed able to prove that hydrogen can be produced continuously for more than 12 days.

According to Prof. Yacoby, the new mutant overcomes two major barriers that have so far hindered continuous production of hydrogen:

  1. Accumulation of oxygen in the process of photosynthesis – As a rule, oxygen poisons the enzyme that produces hydrogen in algae, but in the mutation, increased respiration eliminates the oxygen and allows favorable conditions for continuous hydrogen production.
  1. Loss of energy to competing processes – And this includes carbon dioxide fixation into sugar. This, too, has been solved in the mutant and most of the energy is being channeled for continuous hydrogen production.

To industrialize these results, the research team led by Prof. Yacoby is working on a pilot program of larger volumes and the development of methods that will allow the time of hydrogen harvest to be extended, in order to reduce its cost to competitive levels. “The rate of hydrogen production from the new mutant reaches one-tenth of the possible theoretical rate, and with the help of additional research it is possible to improve it even further,” concludes Prof. Yacoby.


Tamar Elman and Prof. Iftach Yacoby in the lab

Featured image: Tamar Elman and the microscopic algae

How are the Birds Coping with Climate Change?

Researchers detect changes in birds’ bodies, probably caused by global warming.

Researchers at Tel Aviv University have found changes in the morphology of many birds in Israel over the past 70 years, which they interpret to be a response to climate change. The body mass of some species decreased, while in others body length increased – in both cases increasing the ratio between surface area and volume. The researchers contend that these are strategies to facilitate heat loss to the environment: “The birds evidently changed in response to the changing climate. However, this solution may not be fully adequate, especially as temperatures continue to rise.”

Relying on the vast bird collection preserved by The Steinhardt Museum of Natural History at TAU, the researchers looked for changes in bird morphology over the past 70 years in Israel. They examined approximately 8,000 adult specimens of 106 different species – including migratory birds that annually pass through Israel (such as the common chiffchaff, white stork, and black buzzard), resident wild birds (like the Eurasian jay, Eurasian eagle-owl, and rock partridge), and commensal birds, that live near humans. They built a complex statistical model consisting of various parameters to assess morphological changes – in the birds’ body mass, body length and wing length – during the relevant period.

The study was led by Prof. Shai Meiri and PhD student Shahar Dubiner of the School of Zoology, 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 scientific journal Global Ecology and Biogeography.

Cooling Down

Prof. Meiri explains that according to Bergmann’s rule, formulated in the 19th century, members of bird and mammal species living in a cold climate tend to be larger than members of the same species living in a warmer climate. This is because the ratio of surface area to volume is higher in smaller animals, permitting more heat loss (an advantage in warm regions), and lower in larger bodies, minimizing heat loss (a benefit in colder climates). Based on this rule, scientists have recently predicted that global warming will lead to a reduction in animal size, with a possible exception: birds living in the human environment (such as pigeons, house sparrows, and the hooded crow) may gain size due to increased food availability, a phenomenon already witnessed in mammals such as jackals and wolves.

Either Long or Slender

Shahar Dubiner: “Our findings revealed a complicated picture. We identified two different types of morphological changes: some species had become lighter – their mass had decreased while their body length remained unchanged; while others had become longer – their body length had increased, while their mass remained unchanged. These together represent more than half of the species examined, but there was practically no overlap between the two groups – almost none of the birds had become both lighter and longer. We think that these are two different strategies for coping with the same problem, namely the rising temperatures. In both cases, the surface area to volume ratio is increased (by either increasing the numerator or reducing the denominator) – which helps the body lose heat to its environment. The opposite, namely a decrease in this ratio, was not observed in any of the species.”


The researchers (from left to right): Shahar Dubiner and Prof. Shai Meiri

Global Phenomenon

Sadly, flying away from global warming is not an option. These findings were observed across the country, regardless of nutrition, and in all types of species: resident birds; commensal species living in the human environment – which, contrary to predictions, exhibited changes similar to those of other birds; and migrants.

A difference was identified, however, between the two strategies: changes in body length tended to occur more in migrants, while changes in body mass were more typical of non-migratory birds. The very fact that such changes were found in migratory birds coming from Asia, Europe, and Africa, suggests that we are witnessing a global phenomenon.

The study also found that the impact of climate change over time on bird morphology (the birds’ change in either weight or length over time, relative to the actual temperature change during that time) is ten times greater than the impact of similar differences in temperature between geographical areas (the birds’ differences in weight or length in different geographical areas, relative to the temperature differences between those areas).

What is the Limit of Evolutionary Flexibility?

Shahar Dubiner: “Our findings indicate that global warming causes fast and significant changes in bird morphology. But what are the implications of these changes? Should we be concerned? Is this a problem, or rather an encouraging ability to adapt to a changing environment? Such morphological changes over a few decades probably do not represent an evolutionary adaptation, but rather certain phenotypic flexibility exhibited by the birds. We are concerned that over such a short period of time, there is a limit to the flexibility or evolutionary potential of these traits, and the birds might run out of effective solutions as temperatures continue to rise.”

Featured image: Israeli birds have become either longer or slenderer over the past 70 years

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