Science Tips: Three Updates from the Weizmann Institute of Science
XENON1T TEAM SETS LIMITS
Weizmann researchers participate in the most sensitive search to date for dark matter
Dr. Ran Budnik and his team at the Weizmann Institute of Science joined 165 researchers from 27 research institutes around the world working on the XENON1T experiment. This experiment is the most sensitive by far to search for dark matter, and the results they reported this week set a stringent limit on the possible mass of particles that could make up the elusive dark matter. Following these results, based on research that utilized a tank containing over a ton of liquid xenon and on data collected for almost a year, the scientists are planning an even larger, more-sensitive experiment – XENONnT – for 2019.
Dark matter is thought to make up 83% of all matter, but is invisible to us as it does not emit light and interacts only very weakly with ordinary matter. One of the candidates for dark matter is weakly interacting massive particles, or WIMPs. XENON1T has been at the forefront of the search for WIMPs. Deep underground at the INFN Laboratori Nazionali del Gran Sasso in Italy, the xenon detector waits for a signal that would report the interaction of a WIMP with a xenon atom. This would appear as a tiny flash of scintillation light and a handful of ionized electrons, which themselves emit tiny flashes of light.
Dr. Budnik and his team in the Department of Particle Physics and Astrophysics worked on the control systems for the XENON1T equipment, their calibration, and statistical interpretation and analysis.
Since the first experiment, in 2005, the XENON collaboration has increased the potential target mass from 5kg to 1,300 kg, while decreasing the background interference by a factor of 5,000. The newest iteration will increase the target four times over, while decreasing the background interference by yet again a factor of 10. “Because the XENON1T setup is so precise,” says Dr. Budnik, “the fact that no background events were detected in the purest region of the detector means that we can now set a limit on the interactions of WIMPs with ordinary matter. The new detector will enable us to search for these particles in a range that cannot be yet observed.”
Dr. Ran Budnik is the incumbent of the Aryeh and Ido Dissentshik Career Development Chair.
BODY KNOWS BEST: A NATURAL HEALING MECHANISM FOR INFLAMMATORY BOWEL DISEASE
The findings suggest that boosting signals in certain cells, but not in others, might even help treat colon cancer
Treating inflammatory diseases of the bowel is extremely challenging: genes, gut microbes, and disrupted immune function all contribute. Weizmann Institute of Science researchers are proposing a way around this complexity. In a study in mice, published in Cell Reports, they have found a way to trigger a natural defense mechanism that prompts the body itself to alleviate intestinal inflammation.
The study, led by veterinarian Dr. Noa Stettner, who is also a PhD student in the lab of Dr. Ayelet Erez in the Department of Biological Regulation, focused on nitric oxide (NO), a signaling molecule involved in a variety of biological processes. Scientists have long tried to determine what role NO plays in such inflammatory conditions as Crohn’s disease and ulcerative colitis, with NO alleviating intestinal inflammation in some circumstances and promoting it in others.
The Weizmann researchers hypothesized that the paradoxical findings might arise because NO has different effects in different types of cells in the gut. The team genetically engineered mice to block NO production exclusively in certain types of cells: either those making up the inner lining of the gut or in immune cells. They found that the symptoms of a colitis-like disease got worse when NO synthesis was blocked in the gut cells, but improved when NO was blocked in the immune cells – particularly in large cells called macrophages.
The scientists concluded that if inflammatory bowel diseases are treated by raising NO levels, it may cause side effects in cells outside the gut lining. Dr. Stettner, with the help of collaborators at the Weizmann Institute and elsewhere, set out to develop a method for boosting NO production only in the gut-lining cells.
They relied on Dr. Erez’s earlier finding that an enzyme called ASL is responsible for the making of the amino acid arginine, the raw material from which the body manufactures NO. The researchers turned to two natural substances: fisetin, present in apples, persimmons, and strawberries, leads to elevated ASL levels; citrulline, found in watermelon, beets, and spinach, increases ASL activity.
The two supplements, when given together, promoted the manufacture of NO exclusively in cells of the inner lining of the gut. Most importantly, the symptoms of an inflammatory disease in the guts of the mice improved significantly.
The treatment also had a beneficial effect on colon cancer, which is known to be aggravated by gut inflammation. In mice with tumors of the colon, intestinal inflammation subsided and the tumors decreased in number and size after the mice receiving the supplements.
If this approach is shown to raise NO levels in the inner lining cells in humans, it may help treat inflammatory bowel diseases − and potentially even colon cancer. The fact that it makes use of over-the-counter nutritional supplements should facilitate its implementation.
Contributors to this research included: Julia Frug, Dr. Alon Silberman, Dr. Alona Sarver, and Dr. Narin N. Carmel-Neiderman of Weizmann’s Department of Biological Regulation; Dr. Chava Rosen, Dr. Biana Bernshtein, Dr. Shiri Gur-Cohen, Dr. Meirav Pevsner-Fischer, Dr. Niv Zmora, and Prof. Steffen Jung of Weizmann’s Department of Immunology; Dr. Raya Eilam, Dr. Inbal Biton, and Prof. Alon Harmelin of Weizmann’s Veterinary Resources Department; Dr. Alexander Brandis of Weizmann’s Life Sciences Core Facilities Department; Dr. Keren Bahar Halpern of Weizmann’s Department of Molecular Cell Biology; Dr. Ram Mazkereth of Tel Aviv University; Dr. Diego di Bernardo and Dr. Nicola Brunetti-Pierri of Federico II University in Naples, Italy; Dr. Gillian Dank of the Hebrew University of Jerusalem; and Dr. Murali Premkumar and Dr. Sandesh C.S. Nagamani of Baylor College of Medicine in Houston, Texas.
Dr. Ayelet Erez’s research is supported by the Adelis Foundation; the Rising Tide Foundation; the Comisaroff Family Trust; the Irving B. Harris Fund for New Directions in Brain Research; and the European Research Council. Dr. Erez is the incumbent of the Leah Omenn Career Development Chair.
PASSING IT ON, THANKS TO PERACH
A mentor helped a lonely child choose a career in science
In the course of writing his doctoral thesis, Emanuel (Emil) Eidin, a student in the Weizmann Institute of Science’s Department of Science Teaching, started thinking about the people he would like to thank in the acknowledgements section. He decided that some of the people to whom gratitude was due were the PERACH mentors who had helped him as a child.
Established over 40 years ago at the Weizmann Institute, PERACH – which in Hebrew is an acronym for “tutoring project” and also means “flower” – is an Israel-wide program in which college students provide one-on-one mentorship for children who are disadvantaged or having trouble in school. Eidin did not remember the surnames of those who had worked with him and so sent an email to the PERACH offices, hoping that someone would find his old mentors.
The email was then posted on Facebook, where it went viral. And the PERACH people located Ra’anan Parpari, the mentor that Eidin remembers as opening up new worlds for by giving him a book. That book was Tolkein’s The Hobbit, and it introduced the lonely boy to the world of fantasy. Parpari and Eidin began communicating on Facebook, eventually getting together for some real face time.
In elementary school, Eidin was a “problematic child” whose grades were low to middling. So the meeting was an emotional one: Eidin told Parpari just how much his help and support had meant to him. “I lived for LEGO, music, and Sherlock Holmes books,” he said. “But in school, if your grades are not good enough, then you are not good enough. Parpari saw me and he could see beyond my grades. And the door he opened for me to the world of fantasy had a real influence on my decision to go into science.” Parpari remembers Emil as a nice, polite child who felt isolated. He helped with homework, but they also played fantasy games together, talked, and went on walks.
When Eidin was an undergraduate, he returned to PERACH: this time to work as a mentor. “Our hope,” he and Parpari say, “is that teachers reading our story will be inclined to look at their students a bit differently, and that more college students will be inspired to join PERACH. That is why we agreed to let people know about our story.”
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The Weizmann Institute of Science in Rehovot, Israel, is one of the world’s top-ranking multidisciplinary research institutions. The Institute’s 3,800-strong scientific community engages in research addressing crucial problems in medicine and health, energy, technology, agriculture, and the environment. Outstanding young scientists from around the world pursue advanced degrees at the Weizmann Institute’s Feinberg Graduate School. The discoveries and theories of Weizmann Institute scientists have had a major impact on the wider scientific community, as well as on the quality of life of millions of people worldwide.