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The study, led by Dr. Marta Acácio as part of her post-doctoral research in Dr. Orr Spiegel's laboratory at Tel Aviv University’s School of Zoology, was conducted in collaboration with Prof. Noa Pinter-Wollman of the University of California, Los Angeles (UCLA) and several other researchers. The findings were published in the prestigious journal PNAS.

Dr. Marta Acácio.

Dr. Orr Spiegel. releasing tagged vultures (Photo credit: Tovale Solomon).

The Eagle Has Landed

Dr. Spiegel explains: “Vultures are a locally endangered species in Israel, with only about 200 individual vultures remaining. They are closely monitored to determine the best possible conservation methods. We thought about what else could be gleaned from the extensive database we have accumulated over the years and agreed it would be interesting to explore how vultures age. Tracking the same individuals in the wild over many years is often very challenging. However, the transmitters we use to monitor the population provided a rare opportunity to observe the aging process in vultures specifically and in animals generally”.

The researchers utilized a database accumulated over 15 years from GPS devices attached to 142 vultures that tracked them for periods of up to 12 years. The vulture, a social bird, sleeps in roosts on cliffs. By cross-referencing the vultures’ ages with the GPS data on their roosting sites, the researchers discovered that as the vultures aged, they increasingly preferred to stay at the same roosting site.

Aging vulture being monitored (Photo credit: Tovale Solomon).

Home Sweet Home

Dr. Spiegel: “It turns out that aging vultures behave a bit like humans and are more inclined to stay at home. When they're young, vultures like to explore new sites and frequently move between places; the likelihood that a young vulture will sleep at the same site two nights in a row is low. When they reach adolescence at the age of five, this behavior stabilizes, and as adults they spend 50 percent of their nights at the same site and the other 50 percent at other sites. When they are old, from the age of 10 onwards, they no longer have the energy to be 'out and about', and return consistently to the same site. Furthermore, when adult vultures do change sites, they do so in a predictable pattern: for example, one night in Ein Avdat, the next in the Small Crater, and the next in Nahal Golhan, following a fixed order. Of course, it could be argued that older vultures move less not because they are old, but because they avoid taking risks in the first place, which is how they reached the age they did. But here we are talking about the exact same individual birds: those who were adventurous at the age of five became more sedentary by age ten”.

Elder Eagles' Poisoning

According to Dr. Spiegel, these fascinating findings on the aging of birds also have very practical implications for conservation efforts. “This new study can help us better protect vultures’ roosting sites in the wild. Additionally, we have now seen that older vultures have fewer social connections, which can help us to prevent poisoning. The transmitters are connected to a system that sends an alert to the Israel Nature and Parks Authority, and to us by phone, if the vulture is not moving or has landed in a dangerous place, indicating that it may have been poisoned.

Collecting dead vultures following poisoning in the Golan Heights by Nature and Parks Authority rangers (Photo credit: Nature and Parks Authority).

Unfortunately, this happens frequently. The danger arises when a vulture descends on a poisoned goat carcass, not knowing that a farmer has poisoned the carcass in order to kill stray dogs. Being social birds, vultures do not come down alone, leading to the risk of dozens of vultures dying at once. Understanding how wide the poisoned vulture’s social circle is will significantly help in mitigating the damage”.

It is important to note that vultures play an important ecological role in the disposing of carcasses. Studies have shown that the extinction of vultures ultimately leads to the loss of human lives, due to the rise of diseases such as rabies. In India, for example, a recently published study revealed that the extinction of vultures due to poisoning resulted in the deaths of half a million people over the course of five years.

A new study at Tel Aviv University found that sponges in the Gulf of Eilat have developed an original way to keep predators away. The researchers found that the sponges contain an unprecedented concentration of the highly toxic mineral molybdenum (Mo). In addition, they identified the bacterium that enables sponges to store such high concentrations of this precious metal and unraveled the symbiosis between the two organisms. The study was led by PhD student Shani Shoham and Prof. Micha Ilan from TAU's School of Zoology. The paper was published in the leading journal Science Advances.

Two Ph.D. candidate Shani Shoham (right) and Raz Marom (Moskovich) happy to finally collect a sponge sample (in the bag) after several dives.

The researchers explain that sponges are the earliest multicellular organisms known to science. They live in marine environments and play an important role in the earth's carbon, nitrogen, and silicon cycles. A sponge can process and filter seawater 50,000 times its body weight daily. With such enormous quantities of water flowing through them, they can accumulate various trace elements – and scientists try to understand how they cope with toxic amounts of materials like arsenic and molybdenum. 

The Hidden Shine of the Sponge

PhD student Shani Shoham: "20 to 30 years ago, researchers from our lab collected samples of a rare sponge called Theonella conica from the coral reef of Zanzibar in the Indian Ocean and found a high concentration of molybdenum. Molybdenum is a trace element, important for metabolism in the cells of all animals including humans, and widely used in industry. In my research, I wanted to test whether such high concentrations are also found in this sponge species in the Gulf of Eilat, where it grows at depths of more than 27 meters. Finding the sponge and analyzing its composition I discovered that it contained more molybdenum than any other organism on earth: 46,793 micrograms per gram of dry weight."

Here's what it looks like under a light microscope: Molybdenum accumulation in the bacterium Entotheonella. You can see the blue in the vacuoles. (Photo: Shani Shoham).

Shoham adds: "Like all trace elements, molybdenum is toxic when its concentration is higher than its solubility in water. But we must remember that a sponge is essentially a hollow mass of cells with no organs or tissues. Specifically in Theonella conica, up to 40% of the body volume is a microbial society - bacteria, viruses, and fungi living in symbiosis with the sponge. One of the most dominant bacteria, called Entotheonella sp., serves as a 'detoxifying organ' for accumulating metals inside the body of its sponge hosts. Hoarding more and more molybdenum, the bacteria convert it from its toxic soluble state into a mineral".

"We are not sure why they do this. Perhaps the molybdenum protects the sponge, by announcing: "I'm toxic! Don't eat me!", and in return for this service the sponge does not eat the bacteria and serves as their host"

Sponge Bling: The Search for Molybdenum

Molybdenum is in high demand, mostly for alloys (for example, high-strength steel). Still, according to Shoham, it would be impracticable to retrieve it from sponges. The concentration is very high, but when translated into weight we could only get a few grams from every sponge, and the sponge itself is relatively rare. Sponges are grown in marine agriculture, mostly for the pharmaceutical industry, but this is quite a challenging endeavor. Sponges are very delicate creatures that need specific conditions".

Shoham continues: "On the other hand, future research should focus on the ability of Entotheonellasp. bacteria to accumulate toxic metals. A few years ago, our lab discovered huge concentrations of other toxic metals, arsenic (As) and barium (Ba), in a close relative of Theonella conica, called Theonella swinhoei, which is common in the Gulf of Eilat. In this case, too, Entotheonellawas found to be largely responsible for hoarding the metals and turning them into minerals, thereby neutralizing their toxicity. Continued research on the bacteria can prove useful for treating water sources polluted with arsenic, a serious hazard which directly affects the health of 200 million people worldwide".

 Prof. Micha Ilan.

The study was led by Prof. Jeff Hausdorff from the Department of Physical Therapy at the Faculty of Medical & Health Sciences and the Sagol School of Neuroscience at Tel Aviv University, and the Center for the Study of Movement, Cognition, and Mobility at the Tel Aviv Medical Center, together with Amit Salomon and Eran Gazit from the Tel Aviv Medical Center. Other investigators included researchers from Belgium, France, and Harvard University. The paper was published in Nature Communications and featured in the Editors’ Highlights.

Prof. Hausdorff, an expert in the fields of gait, aging, and Parkinson's disease, explains: "FOG is a debilitating and so far unexplained phenomenon, affecting 38-65% of Parkinson's sufferers. A FOG episode can last from a few seconds to more than a minute, during which the patient's feet are suddenly 'glued' to the floor, and the person cannot begin or continue walking. FOG can seriously impair the mobility, independence, and quality of life of people with Parkinson’s disease, causing great frustration, and frequently leading to falls and injuries".

Amit Salomon adds: "Today the diagnosis and tracking of FOG are usually based on self-report questionnaires and visual observation by clinicians, as well as frame-by-frame analysis of videos of patients in motion. This last method, currently the prevailing gold standard, is reliable and accurate. Still, it has some serious drawbacks: it is time-consuming, requires the involvement of at least two experts, and is impracticable for long-term monitoring in the home and daily living environment. Researchers worldwide are trying to use wearable sensors to track and quantify patients' daily functioning. So far, however, successful trials have all relied on a very small number of subjects".

TAU's AI Challenge Advances FOG Tracking

In the current study, the researchers collected data from several existing studies, relating to over 100 patients and about 5,000 FOG episodes. All data were uploaded to the Kaggle platform, a Google company that conducts international machine learning competitions. Members of the worldwide machine learning community were invited to develop models that would be incorporated into wearable sensors to quantify various FOG parameters (e.g. duration, frequency, and severity of episodes). A prize of $100,000, funded by Kaggle and the Michael J. Fox Foundation for Parkinson's Research, was offered for the best solutions. 1,379 groups from 83 countries rose to the challenge, ultimately submitting a total of 24,862 solutions. The results of the best models were very close to those obtained through the video analysis method, and significantly better than previous experiments relying on a single wearable sensor.

Moreover, the models led to a discovery: an interesting relationship between FOG frequency and the time of day. Co-author Eran Gazit notes: "We observed, for the first time, a recurring daily pattern, with peaks of FOG episodes at certain hours of the day, that may be associated with clinical phenomena such as fatigue, or effects of medications. These findings are significant for both clinical treatment and continued research about FOG".

Prof. Hausdorff: "Wearable sensors supported by machine learning models can continuously monitor and quantify FOG episodes, as well as the patient's general functioning in daily life. This gives the clinician an accurate picture of the patient's condition at all times: has the illness improved or deteriorated? Does it respond to prescribed drugs? The informed clinician can respond promptly, while data collected through this technology can support the development of new treatments. In addition, our study demonstrates the power of machine learning contests in advancing medical research. The contest we initiated brought together capable, dynamic teams all over the world, who enjoyed a friendly atmosphere of learning and competition for a good cause. Rapid improvement was gained in the effective and precise quantification of FOG data. Moreover, the study laid the foundations for the next stage: long-term 24/7 FOG monitoring in the patient's home and real-world environment".

The research was conducted under the leadership of Prof. Yasmine Meroz from the School of Plant Sciences and Food Security at the Wise Faculty of Life Sciences at Tel Aviv University, in collaboration with Prof. Orit Peleg from the University of Colorado Boulder in the USA. The research team included Dr. Chantal Nguyen (Boulder), Roni Kempinski and Imri Dromi (TAU). The research was published in the prestigious journal Physical Review X.

Do flowers have a sense of direction?

Prof. Meroz explains: "Previous studies have shown that if sunflowers are densely planted in a field where they shade each other they grow in a zigzag pattern - one forward and one back - so as not to be in each other's shadow. This way they grow side by side to maximize illumination from the sun, therefore photosynthesis, on a collective level. Plants know how to distinguish between the shadow of a building and the green shadow of a leaf. If they sense the shadow of a building - they usually don’t change their growth direction, because they 'know' that will have no effect. But if they sense the shadow of a plant, they will grow in a direction away from the shadow".

According to the researchers, Darwin was the first to recognize that all plants grow while exhibiting a kind of cyclical movement known as "circumnutation", which is observed in both stems and roots. However, until today—except for a few cases, such as climbing plants that grow in large circular movements to find something to grab onto—it was unclear whether this was an artifact or a critical feature of growth. Why would a plant invest energy to grow in random directions?

In the current study, the researchers examined how sunflowers "know" to grow optimally—maximizing sunlight capture for the collective—and analyzed the growth dynamics of sunflowers in the laboratory, where they exhibit a zigzag pattern. Prof. Meroz and her team grew sunflowers in a high-density environment and photographed them during growth, taking pictures every few minutes. The photographs were then combined to create a time-lapse movie. By tracking the movement of each sunflower, the researchers observed that the flowers were "dancing" a lot.

Shake your Tail Petal

Prof. Meroz stated, "As part of our research, we conducted a physical analysis that captured the behavior of each sunflower within the collective, revealing that the sunflowers 'dance' to find the optimal angle, ensuring that each flower does not block the sunlight of its neighbor. We quantified this movement statistically and demonstrated through computer simulations that these random movements are used collectively to minimize shadowing. It was also surprising to find that the distribution of the sunflowers' 'steps' was very wide, ranging over three orders of magnitude, from nearly zero displacements to movements of up to two centimeters every few minutes in various directions".

In conclusion, Prof. Meroz adds: "The sunflower plant takes advantage of its ability to use both small, slow steps and large, fast ones to find the optimal arrangement for the collective. If the range of steps were smaller or larger, the arrangement would result in more mutual shading and less photosynthesis. It's somewhat like a crowded dance party, where individuals move around to create more space: if they move too much, they'll interfere with the other dancers, but if they move too little, the crowding problem won't be solved, leaving one corner of the square overcrowded and the other empty. Sunflowers exhibit a similar communication dynamic—a combination of responding to the shade of neighboring plants and making random movements regardless of external stimuli".