Tag: Life Sciences

TAU Researchers Found the Cause of Sea Urchin Deaths in the Red Sea, Potentially Threatening Coral Reefs Worldwide.

A New TAU Study Shows that Global Warming and Deforestation Could Cause Mass Animal Extinctions.

A joint study by TAU and the University of Colorado (CU) states that the combination of global warming and extreme heat events, alongside the continued expansion of deforestation in the world, may be devastating for many species of animals, especially those that know how to climb trees. As part of the study, the researchers focused on lizards and showed that following the effects of climate change, they will seek refuge from the hot ground by spending a lot of time on trees. However, due to human-related activities, such as deforestation, urbanization and the expansion of agricultural lands at the expense of natural lands, the availability of trees in the areas where the lizards live will decrease, and this may lead to the collapse of many populations.

The research was conducted under the leadership of doctoral student Omer Zlotnick from the laboratory of Dr. Ofir Levy at the School of Zoology, the Wise Faculty of Life Sciences and the Steinhardt Museum of Natural History at TAU and in collaboration with Dr. Keith Musselman from CU. The study was published in the journal Nature Climate Change. 

Climate Crisis: Animals Seeking Comfort in Trees

The researchers explain that the climate crisis and global warming force animals to search for more comfortable places to stay to escape the extreme heat, just as we look for a shady area on a hot day. For climbing animals, trees can serve as a comfortable and pleasant refuge. One of the reasons for this is that the farther you get from the ground, the lower the air temperature gets, and the stronger the wind becomes. Therefore, on hot days, for example, animals can climb up trees to escape from the hot ground.

The importance of trees, then, is expected to increase as the climate warms. The problem is that in many places in the world, the density of trees is decreasing, mainly due to phenomena such as deforestation and the expansion of the use of trees for various purposes such as construction, etc. This phenomenon creates a situation where, on the one hand, due to climate change, animals will depend more on trees for their survival, while on the other hand, the destruction of habitats will lead to a decrease in the availability of trees.

Lizards’ Habitat Loss

Doctoral student Omer Zlotnik: “As part of the research, we wanted to examine how the combined effect of these two processes would be on animals. Specifically, we focused on lizards because they are very dependent on their environment to maintain a normal body temperature, and a lack of comfortable places to stay can affect them dramatically. In the study, we used a computer simulation to simulate where the lizard should be, in the sun, in the shade, or on the tree, every minute for 20 years, under the climate conditions that existed in the past and under those expected in the future. Using the simulation, we examined how populations of lizards would be affected by climate change when trees are available and how their situation would change following the felling of trees in their habitat”.

Left to right – Dr. Ofir Levy & Omer Zlotnick

The results showed that, in general terms, climate change is going to benefit many lizard populations. In most places, the expected warming will allow lizards to be active longer throughout the day and the year, as there will be fewer times when it is too cold to come out of their burrows. However, when climate change occurs at the same time as the felling of trees, the trend is likely to reverse, so that many lizard populations may collapse. In areas with a warm climate, climate change, even if no trees are cut down, is expected to harm lizard populations, and cutting down trees will make the situation even worse.

“What’s really interesting about lizards is that they just need to be able to move a short distance around the tree trunk to get to a very different climate and habitat environment”, said Keith Musselman, an assistant professor in the Department of Geography and CU Boulder’s Institute of Arctic and Alpine Research. 

Musselman: “These microhabitats are particularly important when we think about how we modify our natural environment and make conservation decisions”.

Dr. Ofir Levy concludes: “Our research focused on lizards, but it actually demonstrates a broader problem that is relevant to many species of animals. Our results demonstrate that trees are crucially important to the ability of animals to cope with climate change, and in many cases, their availability can be, for the animals, the difference between crawling and collapsing. Our research proves how important it is to preserve forested areas and trees in general, especially in light of the changing climate. As part of the research, we also provide more practical tools for decision-makers, such as the height or density of trees required in different areas. We hope that this research will be used to build more effective programs for the conservation and restoration of natural areas so that we can provide the animals with what they need to survive”.

How Does Global Warming Impact Fish Abundance?

Bacteria-Targeting Viruses Adapt, Improving their Decision-Making.

Pendulum Experiment Sheds Light on Quantum Mysteries in Topological Materials, Revealing Insights Unreachable by Traditional Methods.

A recent study conducted at Tel Aviv University has devised a large mechanical system that operates under dynamical rules akin to those found in quantum systems. The dynamics of quantum systems, composed of microscopic particles like atoms or electrons, are notoriously difficult, if not impossible, to observe directly. However, this new system allows researchers to visualize phenomena occurring in specialized “topological” materials through the movement of a system of coupled pendula.   The research is a collaboration between Dr. Izhar Neder of the Soreq Nuclear Research Center, Chaviva Sirote-Katz of the Department of Biomedical Engineering, Dr. Meital Geva and Prof. Yair Shokef of the School of Mechanical Engineering, and Prof. Yoav Lahini and Prof. Roni Ilan of the School of Physics and Astronomy at Tel Aviv University and was recently published in the Proceedings of the National Academy of Sciences of the USA (PNAS).       Exploring Quantum Wave Phenomena   Quantum mechanics governs the microscopic world of electrons, atoms and molecules. An electron, which is a particle that moves in an atom or in a solid, may have properties that give rise to wave-like phenomena. For instance, it may demonstrate a probability of dispersing in space similar to waves spreading out in a pool after a stone is thrown in, or the capability to exist simultaneously in more than one place.     Such wave-like properties lead to a unique phenomenon that appears in some solid isolators, where even though there is no electric current through them, and the electrons do not move due to an external electric voltage, the internal arrangement of the material shows up in a state referred to as “topological”. This means that the wave of electrons possesses a quantity that can “close on itself” in different ways, somewhat like the difference between a cylinder and a Möbius strip. This “topological” state of the electrons, for which the 2016 Nobel Prize in Physics was awarded, is considered a new state of matter and attracts much current research.   Chaviva Sirote-Katz   Despite the theoretical interest, there is a limitation in measuring these phenomena in quantum systems. Due to the nature of quantum mechanics, one cannot directly measure the electron’s wave function and its dynamical evolution. Instead, researchers indirectly measure the wave-like and topological properties of electrons in materials, for instance by measuring the electrical conductivity at the edges of solids.     In the current study, the researchers considered the possibility of constructing a sufficiently large mechanical system that would adhere to dynamical rules akin to those found in quantum systems, and in which they could directly measure everything. To this end, they built an array of 50 pendula, with string lengths that slightly varied from one pendulum to the other. The strings of each neighboring pair of pendula were connected at a controlled height, such that each one’s motion would affect its neighbors’ motion.     Quantum Pendulum Insights   On one hand, the system obeyed Newton’s laws of motion, which govern the physics of our everyday lives, but the precise lengths of the pendula and the connections between them created a magical phenomenon: Newton’s laws caused the wave of the pendulum’s motion to approximately obey Schrödinger’s equation – the fundamental equation of quantum mechanics, which governs the motion of electrons in atoms and in solids. Therefore, the motion of the pendula, which is visible in the macroscopic world, reproduced the behaviors of electrons in periodic systems such as crystals.     The researchers pushed a few pendula and then released them. This generated a wave that propagated freely along the chain of pendula, and the researchers could directly measure the evolution of this wave – an impossible mission for the motion of electrons. This enabled the direct measurement of three phenomena. The first phenomenon, known as Bloch oscillations, occurs when electrons within a crystal are influenced by an electric voltage, pulling them in a specific direction. In contrast to what one would expect, the electrons do not simply move along the direction of the field, but they oscillate back and forth due to the periodic structure of the crystal. This phenomenon is predicted to appear in ultra-clean solids, which are very hard to find in nature. In the pendula system, the wave periodically moved back and forth, exactly according to Bloch’s prediction.     The second phenomenon that was directly measured in the pendula system is called Zener tunneling. Tunneling is a unique quantum phenomenon, which allows particles to pass through barriers, in contrast to classical intuition. For Zener tunneling, this appears as the splitting of a wave, the two parts of which then move in opposite directions. One part of the wave returns as in Bloch oscillations, while the other part “tunnels” through a forbidden state and proceeds in its propagation. This splitting, and specifically its connection to the motion of the wave in either direction, is a clear characteristic of the Schrödinger equation.     In fact, such a phenomenon is what disturbed Schrödinger, and is the main reason for the suggestion of his famous paradox; according to Schrödinger’s equation, the wave of an entire cat can split between a live-cat state and a dead-cat state. The researchers analyzed the pendula motion and extracted the parameters of the dynamics, for instance, the ratio between the amplitudes of the two parts of the split wave, which is equivalent to the quantum Zener tunneling probability. The experimental results showed fantastic agreement with the predictions of Schrödinger’s equation.     The pendula system is governed by classical physics. Therefore, it cannot mimic the full richness of quantum systems. For instance, in quantum systems, the measurement can influence the system’s behavior (and cause Schrödinger’s cat to eventually be dead or alive when it is viewed). In the classical system of macroscopic pendulum, there is no counterpart to this phenomenon. However, even with these limitations, the pendula array allows the observation of interesting and non-trivial properties of quantum systems, which may not be directly measured in the latter.     The third phenomenon that was directly observed in the pendula experiment was the wave evolution in a topological medium. Here, the researchers found a way to directly measure the topological characteristic from the wave dynamics in the system – a task that is almost impossible in quantum materials. To this end, the pendula array was tuned twice, so that they would mimic Schrödinger’s equation of the electrons, once in a topological state and once in a trivial (i.e. standard) state. By comparing small differences in the pendulum motion between the two experiments, the researchers could classify the two states. The classification required a very delicate measurement of a difference between the two experiments of exactly half a period of oscillation of a single pendulum after 400 full oscillations that lasted 12 minutes. This small difference was found to be consistent with the theoretical prediction.     The experiment opens the door to realizing further situations that are even more interesting and complex, like the effects of noise and impurities, or how energy leakage affects wave dynamics in Schrödinger’s equation. These are effects that can be easily realized and seen in this system, by deliberately perturbing the pendula motion in a controlled manner.

When the Humans Are Away, Do the Crows Still Play?

A new study from Tel Aviv University examined what happens to birds that are accustomed to living around humans, when their habitat is suddenly emptied of the presence of humans. The study found that when humans are suddenly absent from the urban environment, the activity of the crows and ringneck parakeets that “live” in the area reduces significantly. Conversely, the graceful prinias, who are generally considered shy, increased their activity.  

Bird’s Eye View

Among other birds, the researchers tested crows, ringneck parakeets (also known as rose-ringed parakeets) and graceful prinias – and the findings are surprising: while the crows and ringneck parakeets, who are characterized by their tendency to “follow” humans, are already accustomed to the noises they make and feed on their food scraps, decreased their activity, the graceful prinias, which are considered shy, actually increased their activity in the same area.   A prinia bird leaninn on a branch.   The research was conducted under the leadership of research student Congnan Sun, Dr. Arjan Boonman and Prof. Yossi Yovel, head of The Sagol School of Neuroscience and a member of The School of Zoology at TAU, in collaboration with Prof. Assaf Shwartz from the Landscape Architecture Department at the Technion. The study’s results were published in ELIFE magazine.  

Birdemic: A Lockdown Story

As part of the current study, the researchers took advantage of the first COVID-19 lockdown to test the interrelationship between man and nature, and placed 17 recording wide-band sensitive microphones in the Yarkon Park and the streets adjacent to it in northern Tel Aviv. With the help of artificial intelligence, an analysis of the recordings from the first days of the lockdown until 10 days after its end (March 25 to May 28) showed that the activity of the crows and ringneck parakeets was significantly lower (the calls from the crows in the park decreased by about 50% during the lockdowns and the chirping of ringneck parakeets in the park dropped by about 90%). In contrast, the graceful prinias actually benefited from the absence of people and increased their presence by about 12%.   Prof. Yossi Yovel explains: “When the first COVID-19 lockdown began, we, like many researchers, in many fields, identified a rare opportunity to conduct field experiments that would examine how animals behave in the absence of humans. In general, many studies indicated the return of species to habitats that humans had ‘abandoned’ because of the coronavirus, but most of these studies were carried out through human observation, which obviously requires humans, who are, as mentioned, the factor whose effect we want to examine. We decided to use microphones to allow us to monitor the activity of birds while humans aren’t present, and to disperse them densely throughout parks and residential neighborhoods. We chose the Yarkon Park area, heading south until Arlozorov Street, and we placed 17 microphones at a distance of about 500 meters away from each other. We chose the ‘old north’ neighborhood of Tel Aviv because it is an urban area adjacent to a park, to enable a comparison between the activity of the birds in a park and the activity of the birds in a city”.   Cry of the Crow The researchers examined the changes in the presence of three particularly common and particularly loud bird species, which differ from each other in the extent to which they exploit humans: hooded crow, ringneck parakeet and graceful prinia. The hooded crow is classified as a “human-following species,” that is, it stays near humans and feeds on their food scraps. The ringneck parakeet is an invasive species, it also follows humans. The graceful prinia is classified as “adaptive” – it adapts itself to humans, and knows how to get along in an urban environment, but does not feed on humans’ food scraps and prefers to avoid their company.     In total, the researchers recorded 3,234 hours containing around 250,000 bird calls, using artificial intelligence to identify the calls and the birds that made them. During the lockdown, human activity in the residential areas increased by 49% and human activity in the Yarkon Park – while leaving homes to go to parks was still prohibited – decreased by 31%.   “First, we found that the overall activity of the birds, regardless of COVID-19, is 53% higher in the parks than in the streets adjacent to them”, explains Prof. Yuval. “The parks are a center of activity for birds, and that is always true. On the other hand, a complex picture emerges from the lockdown period. The crows and ringneck parakeets, which usually subsist on leftover food from people in the park, searched for other avenues. The calls from the crows in the park decreased by about 50%, and the chirping of the ringneck parakeets in the park dropped by around 90%. Conversely, the shy graceful prinia, an outstanding adaptor, increased its activity by about 12%. These findings highlight the fact that there are animals that depend on us in the city, as well as the flexibility of these animals and the complexity and diversity of the urban ecosystem”.

Can better rooting in plant cloning improve crop variety, cost, and climate resilience?

Using CRISPR technology, researchers succeed in growing tomatoes that consume less water without compromising yield.

A new discovery by Tel Aviv University has succeeded in cultivating and characterizing tomato varieties with higher water use efficiency without compromising yield. The researchers, employing CRISPR genetic editing technology, were able to grow tomatoes that consume less water while preserving yield, quality, and taste.

The research was conducted in the laboratories of Prof. Shaul Yalovsky and Dr. Nir Sade, and was led by a team of researchers from the School of Plant Sciences and Food Security at Tel Aviv University’s Wise Faculty of Life Sciences. The team included Dr. Mallikarjuna Rao Puli, a former postdoctoral fellow supervised by Prof. Yalovsky, and Purity Muchoki, a doctoral student jointly supervised by Prof. Yalovsky and Dr. Sade. Additional students and postdoctoral fellows from TAU’s School of Plant Sciences and Food Security, along with researchers from Ben Gurion University and the University of Oregon, also contributed to the research. The study’s findings were published in the academic journal PNAS.

The researchers explain that in light of global warming and the diminishing of freshwater resources, there is a growing demand for agricultural crops that consume less water without compromising yield. Naturally, at the same time, because agricultural crops rely on water to grow and develop, it is particularly challenging to identify suitable plant varieties.

In a process called transpiration, plants evaporate water from their leaves. Concurrently, carbon dioxide enters into the leaves, and is assimilated into sugar by photosynthesis, which also takes place in the leaves. These two processes — transpiration and carbon dioxide uptake — occur simultaneously through special openings in the surface of leaves called stomata. The stomata can open and close, serving as a mechanism through which plants regulate their water status.

The researchers highlight that under drought conditions, plants respond by closing their stomata, thereby reducing water loss by transpiration. The problem is that due to the inextricable coupling between the transpiration of the water and the uptake of carbon dioxide, the closing of the stomata leads to a reduction in the uptake of carbon dioxide by the plant. This decrease in carbon dioxide uptake leads to a decline in the production of sugar by photosynthesis. Since plants rely on the sugar generated in photosynthesis as a vital energy source, a reduction in this process adversely affects plant growth.

In crop plants, the decline in photosynthetic sugar production manifests as a decline in both the quantity and quality of the harvest. In tomatoes, for example, the damage to the crop is reflected in a decrease in the number of fruits, their weight, and the amount of sugar in each fruit. Fruits with lower sugar content are less tasty and less nutritious.

In the present study, the researchers induced a modification in the tomato through genetic editing using the CRISPR method, targeting a gene known as ROP9. The ROP proteins function as switches, toggling between an active or inactive state.

Prof. Yalovsky: “We discovered that eliminating ROP9 by the CRISPR technology cause a partial closure of the stomata. This effect is particularly pronounced during midday, when the rate of water loss from the plants in the transpiration process is at its highest. Conversely, in the morning and afternoon, when the transpiration rate is lower, there was no significant difference in the rate of water loss between the control plants and ROP9-modified plants. Because the stomata remained open in the morning and afternoon, the plants were able to uptake enough carbon dioxide, preventing any decline in sugar production by photosynthesis even during the afternoon hours, when the stomata were more closed in the ROP9-modified plants.”

To assess the impact of the impaired ROP9 on the crop, the researchers conducted an extensive field experiment involving hundreds of plants. The results revealed that although the ROP9-modified plants lose less water during the transpiration process, there is no adverse effect on photosynthesis, crop quantity, or quality (the amount of sugar in the fruits). Furthermore, the study identified a new and unexpected mechanism for regulating the opening and closing of the stomata, related to the level of oxidizing substances, known as reactive oxygen species, in the stomata. This discovery holds significant implications for basic scientific knowledge as well.

Dr. Sade: “There is great similarity between the ROP9 in tomatoes and ROP proteins found in other crop plants such as pepper, eggplant and wheat. Therefore, the discoveries detailed in our article could form the basis for the development of additional crop plants with enhanced water use efficiency, and for a deeper understanding of the mechanisms behind stomatal opening and closing.”

Prof. Stephen Quake visited Tel Aviv University and talked about science and collaboration.

Prof. Stephen Quake, the head of science at the Chan Zuckerberg Initiative, visited Tel Aviv University recently and met with its leading scientists.

CZI, which was founded by Facebook’s co-founder Mark Zuckerberg and his wife Priscilla Chan in 2015, is looking to diversify and expand its scientific grant programs, and Quake’s visit was an important step in building cooperation between the Intitative’s and the University’s science communities.

 

“Mark and Priscilla’s goal is to cure, manage or treat all human disease over the course of the century.” 

 

“Mark and Priscilla have decided to give their entire fortune away in their lifetime. Their goal is to achieve a lot … and in science it is to cure, manage or treat all human disease over the course of the century—to try to stimulate the global research community to do it,” said Quake upon being interviewed on Tel Aviv University’s podcast channel, TAU Unbound.

To achieve that, Quake said, CZI’s decision has been “to focus on basic science for a couple of decades—that’s where we think transformative breakthroughs will come from.”

 

 

Currently, CZI is funding research through grants in about 30 different countries, including 9 in Israel. Grant support is given in five broad areas: cell biology, neuroscience, imaging, rare diseases and genome science, and open science, explained Quake.

Another way CZI is catalyzing breakthroughs is by establishing bio-hubs—institutes that partner with “great universities” to take on “a big decade-long problem that they wouldn’t do on their own, be a nexus for driving that collaboration.” For now, CZI has two institutes based in the US, but may consider opening an international bio-hub in the future. “Nobody has all the answers themselves, science goes faster when you share knowledge,” said Quake replying to a question about why international collaboration is important. In the podcast, he also outlined the procedure and criteria for CZI’s grant-giving.

Besides speaking on the podcast, Prof. Quake and the CZI delegation met with a group of TAU’s leading scientists headed by Prof. Dan Peer, TAU’s VP of Research& Development, as well as with the University’s President Prof. Ariel Porat, and the VP for Resource Development, Amos Elad.

“TAU is looking forward to expanding collaboration with the Chan Zuckerberg Initiative, which is an amazing organization with the potential to do great things for humanity,” said President Ariel Porat.