Tag: life sciences

Hitting Rock Bottom?

First meta-analysis of its kind shows warming of Mediterranean Sea causes marine species to migrate.

As has been heavily discussed at the recent the UN Climate Change Conference (COP26) in Glasgow, our entire planet has been warming in recent decades. This process has been particularly marked in the Mediterranean Sea, where the average water temperature rises by one degree every thirty years, and the rate is only accelerating. One of the urgent questions that must be asked is how, if at all, the various species living in the Mediterranean will adapt to this sudden warming.

In recent years, evidence has accumulated that some species have deepened their habitats in order to adapt to global warming, while other studies have found that species are limited in their ability to deepen into cooler water. A new TAU study shows that there are species of marine animals such as fish, crustaceans and mollusks (for example squid) that change their habitats and deepen an average of 55 meters across the climatic gradient of the Mediterranean (spanning a range of 60 C) to live in cooler waters.

The Mediterranean – An Ideal Test Case

“It should be remembered that the Mediterranean was hot in the first place, and now we are reaching the limit of many species’ capacity,” explains Prof. Jonathan Belmaker from the School of Zoology in The George S. Wise Faculty of Life Sciences. “Moreover, the temperature range in the Mediterranean is extreme – cold in the northwest and very hot in the southeast. Both of these factors make the Mediterranean an ideal test case for species’ adaptation to global warming.”

The groundbreaking study was led by PhD student Shahar Chaikin under the supervision of Prof. Jonathan Belmaker, and along with researchers Shahar Dubiner, all from the School of Zoology in The George S. Wise Faculty of Life Sciences and The Steinhardt Museum of Natural History at Tel Aviv University. The results of the study were published in the journal Global Ecology and Biogeography, and have far-reaching implications for both fishing and future marine nature reserves.

Life at the Bottom

Cause for Preparation

The results of the study have many implications for the future, in the Mediterranean and in general, given that the response of each species to rising temperatures can be predicted according to its traits, such as temperature preference. This, for the first time, offers researchers the opportunity to forecast changes in the composition of the marine community, as well as for the public the opportunity to prepare for these changes accordingly.

“Our research clearly shows that species do respond to climate change by changing their depth distribution,” Chaikin concludes, “and when we think about the future, decision-makers will have to prepare in advance for the deepening of species. For example, future marine nature reserves will need to be defined so that they can also provide shelter to species that have migrated to greater depths. And on the other hand, fishing in the future will involve fishing the same fish at greater depths, which means sailing further into the sea and burning more fuel.”

So, How Deep is Our Love?

In the framework of the study, the Tel Aviv University researchers conducted a meta-analysis of data on the depth distribution of 236 marine species collected in previous bottom-trawl surveys. The data collected revealed for the first time that species deepen their minimum depth limits in parallel with warming seawater temperatures, from the west to the east Mediterranean, and on average deepen 55 meters across the Mediterranean (a range of 60 C).

However, the pattern of deepening is not uniform between species: cold-water species were found to deepen significantly more than warm-water species, species that live along a narrow depth range deepen less than species that live along a wide depth gradient, and species that can function within in a wider temperature range deepen more than those who can function only within a narrow temperature range.

“Various studies collect fishing data from trawling – that is, a boat that drags a net along the seabed and collects various species – and these studies often also measure the depth at which the species were caught in the net,” says Shahar Chaikin. “We cross-referenced these data with water temperature data, and by analyzing 236 different species we came to a broad and compelling conclusion: there has been a deepening of the depth limits of species’ habitats. The minimum depths for species in the Mediterranean are getting deeper, while the maximum depths remain stable. The deepening effect was found to be more significant among cold-water species. In contrast, there are species that function within a narrow temperature range and at a certain depth that deepen much less, probably because they cannot survive in deeper water.”

 

“Even if species deepen to escape the warm waters and this rapid adaptation helps them, there is still a limit – and that limit is the seabed,” adds Prof. Belmaker. “We are already seeing deep-sea fish like cod whose numbers are declining, probably because they had nowhere deeper to go.”

Seahorses – Slow, but Fierce

Terrible swimmers with incredible preying capability.

Seahorses are not exactly Olympic swimmers, in fact they’re considered to be particularly poor swimmers. Despite being relatively slow, however, they are adept at preying on small, quick-moving animals. In a new study conducted at Tel Aviv University, researchers have succeeded in characterizing the incredible preying capability of seahorses, discovering that they can move their head up at the incredible speed of 0.002 seconds. The rapid head movement is accompanied by a powerful flow of water that snags their prey right into the seahorse’s mouth. How was this spring mechanism formed? When did it develop? The researchers hope the recent study will lead to further studies designed to help solve the riddle of spring fish.

The study was led by Prof. Roi Holzman and the doctoral student Corrine Jacobs of the School of Zoology at The George S. Wise Faculty of Life Sciences and the Steinhardt Museum of Natural History at Tel Aviv University, and was conducted at the Interuniversity Institute for Marine Sciences in Eilat. The study was published in the Journal of Experimental Biology.

Springing to Action

The researchers explain that seahorses are fish that possess unique properties such as male ‘pregnancy’, square tail vertebrae, and of course the unique eating system. For most of the day, seahorses are anchored with their tail to seaweeds or corals with their head tilted downward, close to their body. However, when they detect prey passing over them, they lift their head at incredible speed and catch it. According to Prof. Holzman, while preying, seahorses turn their body into a kind of spring: using their back muscles, they stretch an elastic tendon, and use their neck bones as a ‘trigger’, just like a crossbow. The result is faster than even the fastest muscle contraction found anywhere in the animal world.

However, until now it was not clear how the spring-loaded mechanism enabled seahorses to actually eat. Just as anyone who tries to remove a fly from a cup of tea knows, water is a viscous medium and the fish needs to open its mouth to create a flow that draws the prey in. But how do seahorses coordinate snagging in prey with their head movement?

In their recent study, researchers from Tel Aviv University succeeded in characterizing and quantifying seahorse movement by photographing their attack at a speed of 4,000 images per second, and using a laser system for imaging water flows. This measurement showed that the ‘crossbow’ system serves two purposes: facilitating head movement and generating high velocity suction currents – 10 times faster than those of similar-sized fish. These advantages enable seahorses to catch particularly elusive prey.

Evolution of the Spring Mechanism

The new measurements also help shed light on the ecology of various species of seahorses, distinguished from each other by the length of their noses. “Our study shows that the speed of head movement and suction currents are determined by the length of a seahorse’s nose”, Prof. Holzman added. “From the evolutionary aspect, seahorses must choose between a short nose for strong suction and moderate head raising, or a long nose for rapid head raising and weaker suction currents. This choice, of course, corresponds to the available diet: long-nosed species catch smaller, quicker animals whereas short-nosed species catch heavier, more ponderous ones.”

 

Prof. Roi Holzman hopes the recent study will lead to further studies to help solve the riddle of spring fish

According to Prof. Holzman, seahorses are not the only instance of the impressive spring mechanism. Actually, seahorses are counted among the family of fish bearing the appropriate scientific name Misfit Fish, including species such as alligator pipefish, shrimpfish, and cornetfish or flutemouths.

“These fish are called that because of their odd shape which enables stretching their body into a spring. The big question applies to the evolution of the spring mechanism, how it was formed and when it developed. I hope our recent study will lead to further studies designed to help solve the riddle of spring fish”. 

Are We Getting to the Root of Cancer?

Groundbreaking discovery that plant roots grow in a spiral motion inspires search for similar motion in cancer cells.

In an interdisciplinary research project carried out at Tel Aviv University, researchers from the School of Plant Sciences affiliated with The George S. Wise Faculty of Life Sciences collaborated with their colleagues from the Sackler Faculty of Medicine in order to study the course of plant root growth. Aided by a computational model constructed by cancer researchers studying cancer cells, adapted for use with plant root cells, they were able to demonstrate, for the first time in the world, and at the resolution of a single cell, that the root grows with a screwing motion – just like a drill penetrating a wall. In the wake of this study, the cancer researchers conjecture that cancer cells, too, are assisted by a spiral motion in order to penetrate healthy tissue in the environment of the tumor, or to create metastases in various organs of the body. The research was led by Prof. Eilon Shani from the School of Plant Sciences and Food Security and Prof. Ilan Tsarfaty from the Department of Clinical Microbiology and Immunology at Tel Aviv University, and was conducted in collaboration with researchers from the USA, Austria and China. The article was published in March 2021 in the acclaimed journal Nature Communications.

Significant Advance in Plant Research – and in the War on Cancer?

The researchers in Prof. Shani’s group, led by Dr. Yangjie Hu, used as a model the plant known as Arabidopsis. They marked the nuclei of the root cells with a fluorescent protein and observed the growing process and movement of the cells at the root tip through a powerful microscope – approximately 1000 cells in each movie. Furthermore, in order to examine what causes and controls the movement, they focused on a known hormone named auxin, which regulates growth in plants. They built a genetic system that enables activation of auxin production (like a switch) in a number of selected cells-types, and then monitored the influence of the on/off mechanism, in four dimensions – the three spatial dimensions and the dimension of time. After each instance of auxin biosynthesis, each of the thousand cells was video recorded for a period of 6 to 24 hours, thus an enormous amount of data accumulated.

WATCH: The process of growth and movement of cells at the root tip using a microscope

For the next stage, the researchers were aided by the computational tools provided by Prof. Tsarfaty, which had been developed in his laboratory for the purpose of monitoring the development of cancerous growths. They used these tools to analyze the imaging data obtained in the study. Thus they were actually able, for the first time, to observe with their own eyes the corkscrew movement of the root, as well as to precisely quantify and chart some 30 root growth parameters relating to time and space – including acceleration, length, changes in cell structure, coordination between cells during the growth process and velocity – for each one of the thousand cells at the root tip. Using fluorescent reporters, the findings even allowed them to precisely assess the movement and the influence of the auxin on the root, and the way in which it controls the growth process. Prof. Shani: “The computational tools that were developed for cancer research have enabled us, for the first time, to precisely measure and quantify the kinetics of growth and to reveal the mechanisms that control it at the resolution of a single cell. By this they have significantly advanced plant research, an area of utmost importance for society – both from an environmental point of view and in terms of agriculture and feeding the population.” Prof. Tsarfaty adds: “This was a synergetic collaboration that benefited and enlightened both parties. In plants, processes take place much more rapidly, and therefore constitute an excellent model for us. In consequence of the findings provided by this plant study, we are presently examining the possibility of a similar screw-like motion in cancer cells and in metastases, in the course of their penetration into adjacent healthy tissues.”

Tel Aviv’s Ecological Oasis: The Yehuda Naftali Botanic Garden at TAU

A donor-supported renovation focuses on research, facilities and visitor access.

By Lindsey Zemler

TAU’s Yehuda  ​Naftali Botanic Garden is a Tel Aviv oasis for all, a collaborative research hub for plant scientists, engineers and neuroscientists, as well as a beautiful urban nature site that welcomes schoolchildren, soldiers and the general public and numbers among the city’s top tourist attractions.

In the last few months, the Garden has been undergoing a massive rejuvenation and enhancement program.

“Thanks to the generous support of Mr. Yehuda Naftali, this long-awaited renovation marks a significant step forward in our mission to be at the cutting edge of botanical research, education and conservation in Israel,” says Prof. Abdussalam Azem, Dean of the George S. Wise Faculty of Life Sciences, to which the Garden belongs. “This project brings us to the next level in improving infrastructure and access.”

Path construction in progress. Photo: Rafael Ben-Menashe.

A priority in planning the renovations, which are almost complete, was to increase access to all corners of the 34-dunam (8-acre) site, including to school groups, families, researchers, and students. This involved making the paths easier to navigate with wheelchairs, strollers, or groups.

Upon entering, the visitor will enjoy seeing native flora in the new beds adjacent to the garden’s western boundary fence, which are placed according to where they are found in Israel, from north to south.  The acacia tree planted by Mr. Naftali at the Garden’s inauguration in 2019 can be found there, growing nicely.

A variety of paths throughout the Garden. (Left): A natural blanket of pine needles is reminiscent of a walk through the Carmel Forest. Photos: Rafael Ben-Menashe.

The main pathways are wide, paved and comfortable for walking in groups. Smaller paths branch out among various habitats to allow visitors an immersive nature experience. They are all designed to emulate natural processes; sometimes a section is left unpaved for water flow.

Water pond with newly added wooden deck. Photo: Moshe Bedarshi.

Rainfall naturally flows downhill and arches in a waterfall to fill a pond, where the addition of wooden decks allows the visitor to stand comfortably at the edge of the water to view wetland plant species.

“When we planned the renovations, we put a lot of thought into the best visitor experience: to create a feeling of being transported to a nature reserve and being able to experience it from close range,” explained Kineret Manevich, Public Outreach Coordinator of the Garden.

New irrigation control center (left) and irrigation pipe (right) in the pine forest habitat. Photos (left) by Rafael Ben-Menashe and (right) by Moshe Bedarshi.

A new computer-controlled irrigation system is part of the critical infrastructure changes in the renovation plan. A large, complex network of pipes provides thousands of plants with essential water.

(Left): Rare plants being cared for in the nursery and (right) image of geo-mapping software. Photo (left) by Rafael Ben-Menashe and (right) courtesy of the Botanic Garden.

The Garden is also an active research center, where every plant is mapped and monitored, creating a robust database of botanical research. In addition, rare plants are rehabilitated and returned to nature.

The Garden offers a complete sensory experience, full of texture, color and shapes.

The area is a living ecosystem providing refuge to plants, animals, and of course, humans seeking nature without leaving Tel Aviv. The Yehuda Naftali Botanic Garden will be open to the public, and together with the adjacent Steinhardt Museum of Natural History will welcome visitors of all kinds.

Victoria

Tok Corporate Centre, Level 1,
459 Toorak Road, Toorak VIC 3142
Phone: +61 3 9296 2065
Email: office@aftau.asn.au

New South Wales

P.O. Box 4044, Maroubra South,
NSW 2035
Phone: +61 418 465 556
Email: davidsolomon@aftau.org.au

Western Australia

P O Box 36, Claremont,
WA  6010
Phone: :+61 411 223 550
Email: clivedonner@thelinqgroup.com