Research Highlights of 2012




Synthetic Antibodies

Prof. Irit Sagi
Institute researchers led by Prof. Irit Sagi turned the tables on the immune system by tricking it into attacking one of the main players in an autoimmune disease. The idea was to create a synthetic version of the active site of an enzyme known as MMP9. MMP9 is a member of a protein family that cuts through such support material as collagen, enabling cellular mobilization and wound healing. But it is also often overactive in autoimmune diseases, in which the immune system mistakenly attacks the body’s own tissues.

As they hoped, the synthetic molecules provoked an immune reaction in mice that was similar, but not identical to, the natural antibodies normally produced to regulate MMP9 activity. When these antibodies, which they dubbed “metallobodies,” were injected into mice with an inflammatory disease similar to Crohn’s, the symptoms were prevented or reversed.

How Traumatic Memories Form

A series of studies in the group of Dr. Rony Paz suggests that the development of post-traumatic stress disorder (PTSD) may be tied to the context in which the disturbing memory is formed.
Dr. Rony Paz


In one series of studies, they showed that the surprise factor – when a stimulus turns from safe to unsafe in an unpredictable manner – makes the memory more resistant and stable, and hence more likely to become traumatic. They found that the formation of resistant memories involves a dialog between two areas of the brain: the cingulate-cortex and the amygdala. This may explain why soldiers are more likely to develop PTSD after being transferred to a new, unfamiliar unit.

In another study, they were able to show that deepbrain-stimulation (DBS), commonly used to treat such neurodegenerative diseases as Parkinson’s, may be used to erase the traumatic memory and prevent its return.

Mix-and-Match Immune Receptors

T cells that are trapped and growing within microwells. Cells are activated by microbeads (black round objects). Dead cells are stained red. From the lab of Dr. Nir Friedman
A sort of immune cell “roulette,” in which the genes for the receptors that identify disease agents are randomly mixed and matched, grants the immune system an unimaginably large number of potential lymphocytes (white blood cells) to deal with new and varied threats. But can this system also ensure that it will have the receptors needed to identify the more common diseases? New research in the lab of Dr. Nir Friedman shows that the mix-and-match process is not entirely random, and he has uncovered some of the factors that shape it.
When the new genes for the receptors are formed, segments of DNA fold over to bring several sequences together. Once the new sequence is cut and pasted together, the unused bits of the DNA segments are discarded. Friedman and his team found that the length and flexibility of these in-between segments influence the likelihood that any particular sequences will be joined in a receptor gene.

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Making Stem Cells

Immunofluorescence staining of MVH protein (green), nuclei (blue), and cell membranes (red) in an adult mouse testis. From the lab of Dr. Jacob Hanna
Institute scientists revealed a piece of the stem cell puzzle: an enzyme that plays a key role in the process of turning an adult cell back into an embryonic-like stem cell. Scientists have learned to reprogram cells, creating so-called induced pluripotent stem cells (iPSCs) by inserting a small number of genes, but the process itself has been a “black box.”
Dr. Jacob (Yaqub) Hanna and his team found that an enzyme called Utx is activated in reprogramming. Utx changes the packaging of the genes, so that hundreds of genes that are normally silenced in the adult cell can be turned on. When the team looked for the original function of this enzyme, they found that it is crucial for the production of sperm or eggs in a developing embryo. So their findings may have relevance for fertility research as well as research on iPSCs.

Plant Mapping

Arabidopsis plants in the lab of Prof. Asaph Aharoni
Even today, plant breeding is mostly a trialand-error affair. In the future, however, those who want to improve certain traits – say the production of a certain vitamin – might consult a map.
Prof. Asaph Aharoni and his colleagues produced such a map – a computerized model of the metabolic pathways of the research plant Arabidopsis. Their model, the most complete one produced to date, is a complex network of biochemical reactions involving thousands of enzymes; and it looks something like an extended map of the London Tube. The lines represent the pathways of metabolic reactions, the trains symbolize individual enzymes and the ends of the lines are the reactions’ end products. Aharoni and his team hope that plant breeders will be able to use the map to get to their objectives in the most direct manner, and to plan their “routes” before they set out.



Green Catalysts

Prof. David Milstein
Prof. David Milstein and his lab group created new catalysts that can enable new chemical reactions of industrial importance – as well as one that might be used to produce green fuel – in an environmentally friendly manner. A catalyst based on the metallic element ruthenium was used to produce polyamides and peptides directly from alcohols and amines. These useful compounds are generally produced in several-step processes and generate a fair amount of waste; but the new method works in a single-step process, and it is selective for the desired compounds with no waste. In other research, Milstein and his team created organo-metallic catalysts and used them to create methanol fuel from CO2 and hydrogen in a very mild, selective, two-step process. In addition, an iron-based catalyst was developed that converts CO2 very efficiently to formic acid. These reactions are also green and mild, and might be used in the future to recycle greenhouse gases.
Milstein was awarded the Israel Prize for chemistry and physics in April for his work in developing green chemistry.

Cold Collisions

Quadropole guide setup in the lab of Dr. Ed Narevicius
Quadropole guide setup in the lab of Dr. Ed Narevicius
A Weizmann Institute team led by Dr. Ed Narevicius conducted experiments that confirmed a long-standing theoretical prediction: At temperatures approaching absolute zero, chemical reactions proceed at a higher rate than would be expected in classical chemistry, due to the quantum effects that enter the picture.
Researchers have been trying to achieve chemical reactions in ultra-cold conditions for over half a century. The Weizmann team managed to get molecules to react at ultra-low temperatures by merging two sub-Kelvin cold beams, so that the relative speeds of the molecules was zero. Once the temperatures dropped below about 3° Kelvin, the researchers began to see signs that quantum phenomena were in play. The reaction rate – normally a monotonic curve – took on peaks and valleys. This was a sign that the particles were acting as waves; the wave interference, at particular energies, led to an increase in reaction rates because of the formation of a short-lived collision complex – a resonance state.



Higgs Boson

Particle collision event in the ATLAS experimen
The European Laboratory for Particle Physics, CERN, announced the discovery of a particle with a mass of 126 GeV. That mass and the observed decay suggest it is the long-sought Higgs boson. This particle, conceived of more than 40 years ago, is the final building block in the Standard Model, which describes the structure of matter, and the force field related to it is believed to endow elementary particles with mass.
Weizmann Institute scientists, including Profs. Eilam Gross, Ehud Duchovni and Giora Mikenberg, have been participants in this research from its outset, as well as taking on crucial leadership roles in ATLAS – one of the two experimental groups that announced the results. The Weizmann Institute has been instrumental in designing and constructing the large, sophisticated radiation detectors used in the ATLAS experiment, as well as in analyzing the data produced by the experiment.

Electron Speed

Artist’s depiction of the tunneling experiment
How long does it take for an electron to pop out of its home and fly back into place? This is a quantum phenomenon known as tunneling, and it takes place in attoseconds – a few billionths of a billionth of a second. Dr. Nirit Dudovich managed to measure that tiny time frame using ultra-fast laser pulses.

With one laser, she induced tunneling in some electrons, and then, with a second laser, gave those electrons a “kick” that sent them off course. Normally, electrons that return home emit a photon as they slide into place; but the ones that were kicked could not get back to their starting point and thus did not emit a photon. In another experiment, Dudovich used a similar technique to time differences in the exit speeds of electrons of different energy levels, recording a time of just 50 attoseconds – possibly one of the shortest intervals ever recorded.

State and Antistate

Nanowires from the lab of Dr. Hadas Shtrikman
Can a particle be its own antiparticle? This idea, first proposed in 1937, is known as a “Majorana particle.” Last year, scientists found hints that such particles may exist when they produced complex “quasi-particles” that lack an electric charge, and therefore present a “state” that is its own “antistate.”
Prof. Yuval Oreg and his group first suggested a way to produce such Majorana-like states in 2010, based on a few well-studied, relatively simple systems. They proposed using a “one-dimensional” (very thin) semiconductor nanowire in proximity to a standard superconductor and applying a weak magnetic field parallel to the nanowire.

Prof. Moty Heiblum and his group, together with Oreg’s group, planned and built such an experimental apparatus and used it to find evidence for the proposed Majorana states. (Three additional groups world-wide found similar evidence for Majoranas, based on Oreg’s theoretical plan.) These Majorana-like states may, among other things, help advance such technology as quantum computing.

Mathematics and Computer Science


Secure Computing in the Cloud

Prof. Shafi Goldwasser and Dr. Zvika Brakerski
As more and more computer services move into the “cloud” – networks of shared, remote servers – security becomes a pressing issue. One way of keeping information safe is to keep it in encrypted form employing fully homomorphic encryption (FHE) – a method that allows one to process data while it is still encrypted – and later decipher the encrypted, processed data in a secure manner.

Research in the group of Prof. Shafi Goldwasser, including her student Dr. Zvika Brakerski, may help make this type of encryption a reality. The original version, proposed in 2009, demonstrated the concept, but was too unwieldy. Brakerski, together with Dr. Vinod Vaikuntanathan, Goldwasser’s former student at MIT, proposed a radically simpler scheme that speeds up processing time. They showed that a mathematical underpinning called ideal lattices, used to represent encrypted data and generate encryption keys in the original scheme, could be replaced by general lattices. Their result promises to pave a path to FHE applications and is the basis for a current large-scale implementation project.

Modeling Disease

Prof. Vered Rom-Kedar
Institute mathematician Prof. Vered Rom-Kedar, working with medical and mathematical researchers, developed a mathematical model to describe what happens in a condition known as neutropenia, which is characterized by low counts of certain white blood cells known as neutrophils. Neutropenia is a common side effect of chemotherapy. In severe neutropenia, the risk of life-threatening infection is known to be high.

The model suggests, however, that some cases of neutropenia may not require aggressive treatment, while others might need to be treated proactively. The new model paints a picture of an immune system in a bistable state – one in which factors that don’t normally affect a healthy immune response can have a large impact in neutropenia. Thus a more detailed analysis, including not only blood counts but the functionality of a patient’s neutrophils and the permeability of their tissues to bacteria, could give doctors a more complete basis for prescribing treatment.