Tough Enough

English
 
Being only one ten-thousandth the thickness of a human hair, yet displaying structural properties akin to those of diamonds, carbon nanotubes are heralded as the biggest of the little things that are set to revolutionize the world. These tiny hollow cylinders made from sheets of hexagonally-arranged carbon atoms could be ideal for use in applications including synthetic muscles, artificial nerve systems that may serve as smart sensors, high-performance car bodies and bridges, as well as novel electronic devices.

What makes them so appealing is that according to theoretical calculations, nanotubes should have incredible mechanical properties – close to the absolute best – rendering them the strongest, hardest, stiffest, toughest material ever to exist. So incorporating these nanotubes into other materials to make composites should greatly enhance those materials’ properties. “But their infinitesimal size makes it hard to prove this experimentally,” explains Prof. Daniel Wagner of the Weizmann Institute of Science’s Materials and Interfaces Department.
 
Together with his postdoctoral fellow Lu-Qi Liu from China, Wagner developed unique methods for creating nanocomposites and probing their mechanical properties. Their method, based on the so-called electrospinning technique, involves injecting the nanotubes into nanofibers in a parallel fashion and then twisting the strands of nanofibers into a microrope structure. They achieved this by attaching the nanofibers to a rotating motor that weaves the strands in a way similar to children dancing with ribbons around a maypole. The results, recently published in Advanced Materials, show that the nanocomposites turn out to be extremely tough. 
 
Prof. Daniel Wagner is the incumbent of the Livio Norzi Professorial Chair.
Chemistry
English
  • Carbon nanotubes
  • Daniel Wagner
  • Materials and Interfaces
  • Nanotechnology

Time-Tested Transplants

English
 
 
In hemophilia, a mutated gene prevents the production of a critical blood-clotting protein. What if the body could be induced – by a transplant of healthy tissue – to begin producing this protein?
 
In research recently published in the Proceedings of the National Academy of Sciences (PNAS), Prof. Yair Reisner and Ph.D. student Anna Aronovich of the Weizmann Institute’s Immunology Department, together with colleagues, showed how such a transplant might in the future be made feasible.
 
By taking spleen tissue from embryonic pigs, the scientists found that harmful T cells, which are responsible for severe immune responses against the recipient, are not present prior to day 42 of gestation. They also found that tissue of this age exhibits optimal growth potential and secretes factor VIII, the blood-clotting protein missing in hemophilic patients. Hemophilic mice with spleen tissue transplanted from pig embryos at 42 days of gestation experienced completely normal blood clotting within a month or two of implantation.
 
Although a number of problems would need to be surmounted before researchers could begin to think of applying the technique to humans, the Institute team has provided evidence that transplanted embryonic tissue, whether human or pig, could one day help the body overcome hemophilia and other such genetic diseases.

Prof. Yair Reisner’s research receives major funding from Tissera Inc. His work is also supported by the J & R Center for Scientific Research; the Belle S. and Irving E. Meller Center for the Biology of Aging; the Gabrielle Rich Center for Transplantation Biology Research; the Abisch Frenkel Foundation for the Promotion of Life Sciences; the Loreen Arbus Foundation; the Crown Endowment Fund for Immunological Research; the Mario Negri Institute for Pharmacological Research – Weizmann Institute of Science Exchange Program; the Charles and David Wolfson Charitable Trust; Dr. and Mrs. Leslie Bernstein, Sacramento, CA; Mr. and Mrs. Irwin Goldberg, Las Vegas, NV; and Mr. and Mrs. Barry Reznik, Brooklyn, NY. Prof. Reisner is the incumbent of the Henry H. Drake Professorial Chair in Immunology.
Life Sciences
English
  • Embryonic development›Embryonic development
  • Immunology
  • Organ transplant
  • Yair Reisner

A Lucky Brake

English

 

400 genes respond to growth signals

 

 

 

 

 

 

When a normal cell complies with a signal telling it to divide, it also begins to activate a “braking system” that eventually stops cell division. If that system is faulty, cancerous growth can result. As reported in Nature Genetics, Weizmann scientists sifted through a huge quantity of data on genes and their activities to identify some of the genes involved in this system of braking.

 

To tackle this monumental task, a team of Weizmann Institute researchers from diverse fields – Prof. Yosef Yarden of the Biological Regulation Department, Prof. Eytan Domany of the Physics of Complex Systems Department, Prof. Uri Alon of the Molecular Cell Biology Department and Dr. Eran Segal of the Computer Science and Applied Mathematics Department – pooled their knowledge and experience. Working with them were Prof. Gideon Rechavi of the Sheba Medical Center and researchers from the M. D. Anderson Cancer Center in Houston, Texas, headed by Prof. Gordon B. Mills.

 

In tests conducted on tissue from ovarian cancer patients, the scientists found a correlation between levels of activity in the “braking” genes, rates of survival and the aggressiveness of the disease. These findings point the way toward the development of a personal genetic profile that might pinpoint the genetic defects responsible for each individual cancer and help doctors tailor a treatment best suited to that particular patient. Such a genetic profile can also help predict the progression of the disease in each case.

 

Also participating in the study were research students Ido Amit, Ami Citri, Gabi Tarcic and Menachem Katz of the Biological Regulation Department and Tal Shay of the Physics of Complex Systems Department.   

 

Prof. Yosef Yarden’s research is supported by the M. D. Moross Institute for Cancer Research; the Goldhirsh Foundation; the Batsheva de Rothschild Foundation; Mr. Daniel Falkner, UK; the estate of Dr. Marvin Klein, Farmington Hills, MI; and Mrs. Bram Laub, Belgium. Prof. Yarden is the incumbent of the Harold and Zelda Goldenberg Professorial Chair in Molecular Cell Biology.

Activity of 400 genes following exposure to a growth signal over time. Red indicates hightened gene activity
Life Sciences
English
  • Biological Regulation
  • Cancer
  • Cancer genetics
  • Eran Segal
  • Eytan Domany
  • Uri Alon
  • Yosef Yarden›Yosef Yarden

Predicting Success

English
(l) Mapping the concentration of a contrast material (simulating a drug) inside the tumor. (r) A mathematical interpreation that "translates" the concentration data into areas of different pressure inside the tumor. the lower the pressure, the greater the concentration.
 
Chemotherapy drugs given intravenously are the mainstay of the fight against cancer. But while these drugs sometimes effect a complete cure, other times they can be almost ineffective. A team headed by Prof. Hadassa Degani of the Biological Regulation Department has come up with a non-invasive method for predicting possible problems. The findings of their studies on animals, which appeared in Cancer Research, may in the future influence treatment regimes for millions of cancer patients. 

Intravenous infusions rely on the bloodstream to carry drugs to where they are needed. Normally, a material such as a chemotherapy drug crosses into a tissue on the principle of concentration equalization – the material diffuses from an area of high concentration to one of low concentration until the concentrations become equal all around. In some cancers, however, even though the material “wants” to spread out evenly, fluids inside the tumor may be exerting pressure, preventing the drug from entering.

The method the Institute scientists developed can measure, with a non-invasive magnetic resonance imaging scan, whether the fluid pressure in the cancerous tissue is at a level that could render chemotherapy ineffective. Degani says that, ideally, the fluid pressure inside the tumor tissue would be checked before a patient begins chemotherapy. If the pressure were discovered to be high, it might be possible to reduce it by various means. The method, if it proves successful in clinical trials, might have the potential to significantly increase the success rate of chemotherapy.  
 
Prof. Hadassa Degani’s research is supported by the M.D. Moross Institute for Cancer Research; the Willner Family Center for Vascular Biology; the Washington Square Health Foundation; Lord David Alliance, CBE, UK; Dr. and Mrs. Leslie Bernstein, Sacramento, CA; Ms. Lynne Mochon and the estate of Edith Degani, New York, NY; Ms. Sophy Goldberg, Israel; and the estate of Julie Osler, New York, NY. Prof. Degani is the incumbent of the Fred and Andrea Fallek Professorial Chair in Breast Cancer Research.
(l) Mapping the concentration of a contrast material (simulating a drug) inside the tumor. (r) A mathematical interpreation that "translates" the concentration data into areas of different pressure inside the tumor. the lower the pressure, the greater the concentration.
Life Sciences
English
  • Biological Regulation
  • Cancer
  • Hadassa Degani
  • MRI diagnosis

Lost in Thought

English
comparison of brain activity: prefrontal areas are significantly activated during introspection, while a completely different network of more posterior areas are active when people are intensely engaged in perceptual tasks
 

Can one literally “lose oneself” in an experience?


Prof. Rafael Malach, Ilan Goldberg and Michal Harel of the Neurobiology Department found a scientific means of addressing this question – by scanning the brains of volunteers performing various mental tasks. The results of their study, published in Neuron, were unanticipated: When subjects were given outwardly focused tasks that demanded their full attention, areas of the brain that relate to the self were not only inactive – they appeared to be vigorously suppressed.

The scientists were particularly interested in certain regions in the prefrontal cortex – a part of the brain known to be involved in personality and self-knowledge, among other things. Brain scans performed with functional magnetic resonance imaging confirmed that these regions were active during introspection, but when subjects were absorbed in a recognition task – such as identifying pieces of music that included a trumpet’s sound – activity in these areas was silenced.

 “It is tempting,” says Malach, “to put these findings in a broader perspective – one that veers away from traditional Western thought, with its emphasis on self-control and ‘someone always minding the store,’ and toward more Eastern perspectives, in which the self must be abandoned in order to engage fully with the outside world.” On a more scientific level, the study suggests that the brain’s self-awareness centers do not function as a critical element that allows perceptual awareness of the outside world. Rather, when we are so occupied with the outside world as to “forget ourselves,” only local, sensory-specific systems seem to be needed.  
 
Prof. Rafael Malach’s research is supported by the Nella and Leon Benoziyo Center for Neurosciences; the Clore Center for Biological Physics; the Carl and Micaela Einhorn-Dominic Brain Research Institute; the Murray H. and Meyer Grodetsky Center for Research of Higher Brain Functions; the A.M.N. Fund for the Promotion of Science, Culture and Arts in Israel; the Edith C. Blum Foundation; and Mr. and Mrs. Irwin Green, Boca Raton, FL. Prof. Malach is the incumbent of the Barbara and Morris Levinson Professorial Chair in Brain Research.
comparison of brain activity: prefrontal areas are significantly activated during introspection, while a completely different network of more posterior areas are active when people are intensely engaged in perceptual tasks
Life Sciences
English
  • Brain research
  • Rafael Malach

Precise Pattern

English
 
A team of researchers led by Prof. Irun Cohen of the Immunology Department has revealed the molecular mechanism of a vaccine for Type 1 diabetes, an autoimmune disorder in which the immune system mistakenly attacks the body's own insulin-producing cells.

The vaccine, which arrests the progression of Type 1 diabetes in laboratory animals, was developed by Cohen and his colleagues several years ago. The scientists had discovered that a particular protein called HSP60, or even only a particular small fragment of it – the peptide p277 – is able to shut down the autommune response causing Type 1 diabetes. Yet although the vaccine is currently being tested in clinical trials in Europe and the United States, its precise mechanism had until recently remained unknown.

As described in a paper published in the Journal of Clinical Investigation, the scientists have now managed to identify the exact immune cells upon which p277 acts, as well as its mechanism of action. They have also shown that to activate this mechanism, p277 must be bound to the receptor TLR-2, which is found on the walls of regulatory immune cells.

“These findings are important: By identifying the molecular activity of p277 with such precision, we can copy nature's own system in regulating the immune response,” says Cohen.

Postdoctoral fellow Dr. Alexandra Zanin-Zhorov spearheaded the project; the other scientists participating in this study were the late Prof. Ofer Lider, Dr. Liora Cahalon, postdoctoral fellow Dr. Guy Tal and Raanan Margalit.  

Prof. Irun Cohen’s research is supported by the Minna James Heineman Stiftung; and the Robert Koch Minerva Center for Research in Autoimmune Disease.
Life Sciences
English
  • Autoimmune
  • Diabetes
  • Immunology
  • Irun Cohen
  • Vaccine

Sensing Trouble

English

A tiny sensor that uses organic molecules to detect problems – from asthma to hidden explosives – has been developed at the Weizmann Institute by Prof. Ron Naaman of the Chemical Physics Department, along with Prof. David Cahen of the Materials and Interfaces Department and Prof. Abraham Shanzer of the Organic Chemistry Department. 

Known as MOCSER (MOle-cular Controlled SEmiconductor Resistor), the sensor can detect minuscule amounts of substances, as little as just a few hundred molecules. These tiny quantities, however, can yield mountains of information. Levels of nitrous oxide (NO) molecules in exhaled breath, for instance, can reveal whether a person is having an asthma attack. The NO sensor has recently been developed as an easy-to-use, accurate asthma detector that can help diagnose the disease or predict attacks.

The sensor is so small that 28 can fit onto a standard electronic chip. MOCSER sensors can be produced inexpensively and might be designed to detect all sorts of substances, including harmful pollutants that are hard to monitor, banned materials and biological molecules.  
   
Prof. Ron Naaman’s research is supported by the Nancy and Stephen Grand Research Center for Sensors and Security; the Fritz Haber Center for Physical Chemistry; the Ilse Katz Institute for Material Sciences and Magnetic Resonance Research; the Wolfson Advanced Research Center for Bio Micro Technology; and the Philip M. Klutznick Fund for Research. Prof. Naaman is the incumbent of the Aryeh and Mintze Katzman Professorial Chair.
Chemistry
English
  • Chemical Physics
  • David Cahen
  • Materials and Interfaces
  • Ron Naaman
  • Sensor

Preserved in Crystal

English

well-preserved ancient DNA in fossil bones

 

Weizmann Institute scientists recently discovered a new source of well-preserved ancient DNA in fossil bones. Their findings were published in the Proceedings of the National Academy of Sciences.
 
Fossil DNA is a potential source of information on the evolution, population dynamics, migrations, diets and diseases of animals and humans. But if it is not well preserved or becomes contaminated by modern DNA, the results are uninterpretable. The scientists, Prof. Stephen Weiner and Michal Salamon of the Institute's Structural Biology Department, working in collaboration with Profs. Baruch Arensburg of Tel Aviv University and Noreen Tuross of Harvard University, may have found a way to overcome these problems
 
In 1986, Weiner first reported the existence of crystal clusters in fresh bones. Now, 20 years later, the scientists have found that the crystal aggregates act as a "privileged niche in fossil bone," protecting the DNA from hostile environments and leaving it relatively undamaged over time. These findings hold much promise for obtaining more reliable and authentic results than has previously been possible from the analysis of ancient DNA in bones.  
 
Prof. Stephen Weiner's research is supported by the Helen and Martin Kimmel Center for Archaeological Science; the Philip M. Klutznick Fund for Research; the Alfried Krupp von Bohlen und Halbach Foundation; the Women's Health Research Center; and Mr. George Schwartzman, Sarasota, FL. Prof. Weiner is the incumbent of the Dr. Walter and Dr. Trude Borchardt Professorial Chair in Structural Biology.
well-preserved ancient DNA in fossil bones
Scientific Archaeology
English
  • Bone formation
  • DNA
  • Scientific Archaeology
  • Stephen Weiner
  • Structural Biology
Yes

Breaking News

English
 
Could engineers have known ahead of time exactly how much pressure the levees protecting New Orleans would be able to withstand before giving way? Is it possible to predict when and under what conditions material wear and tear will become critical, causing planes to crash or bridges to collapse? Weizmann Institute scientists have taken a new and original approach to the study of how materials fracture and crack.
 
Physicists attempting to find a formula for the dynamics of cracking have faced a serious obstacle. The difficulty lies in pinning down, objectively, the fundamental directionality of the cracking process: From any given angle of observation or starting point of measurement, the crack will look different and yield different results. Until now, no one has successfully managed to come up with a method for analyzing the progression of a forming crack.
 
To address this problem, Prof. Itamar Procaccia and research students Eran Bouchbinder and Shani Sela of the Chemical Physics Department first divided up the cracks' ridged surfaces into mathematically determined sectors. For each sector they were able to measure and evaluate different aspects of the crack's formation and assign it simple directional properties. After some complex data analysis of the combined information from all the sectors, the team found their method allowed them to gain a deeper understanding of the process of cracking, no matter which direction the measurements started from. They then successfully applied the method to a variety of materials - plastic, glass and metal.
 
The team's method will give engineers and materials scientists new tools to understand how basic materials act under different stresses, to predict how and when microscopic or internal, unseen fractures might turn life-threatening, or to improve these materials to make them more resistant to the formation or spread of cracks.
 
Prof. Itamar Procaccia's research is supported by the Minerva Center for Nonlinear Physics of Complex Systems; and the Naftali and Anna Backenroth-Bronicki Fund for Research in Chaos and Complexity. Prof. Procaccia is the incumbent of the Barbara and Morris L. Levinson Professorial Chair in Chemical Physics.
Chemistry
English
  • Chemical Physics
  • Cracking
  • Itamar Procaccia
  • Materials science

Triple Code

English
 
Is there a universal neural code for sensation, similar to the genetic code, in which the complexity of sense and experience can be reduced to a few simple rules? According to Prof. Ehud Ahissar of the Weizmann Institute's Neurobiology Department, who studies how rats use their whiskers to sense their environment, the answer might be no.
 
To get a fix on their surroundings, rats whisk their whiskers back and forth as they move about. But how does the rat's brain map out a three-dimensional object using this movement? Sensing begins in the neurons at the whisker bases, which then fire signals off to the brain. The scientists, Marcin Szwed, Knarik Bagdasarian and Ahissar, found that the neurons encode information in a completely different form when perceiving each of the three dimensions in the rat's immediate surroundings - the horizontal, the vertical and the radial (distance from the whisker base). In other words, three different types of code are involved in the seemingly simple act of feeling out a three-dimensional object. 
 
Prof. Ehud Ahissar's research is supported by the Nella and Leon Benoziyo Center for Neurosciences; the Carl and Micaela Einhorn-Dominic Institute for Brain Research; the Irving B. Harris Foundation; the Edith C. Blum Foundation; and Ms. Esther Smidof, Switzerland. Prof. Ahissar is the incumbent of the Helen Diller Family Professorial Chair in Neurobiology.
Life Sciences
English
  • Brain
  • Ehud Ahissar
  • Perception

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