Biomedical Beat—a digest of research advances, scientist profiles, cool images and more

September 2013 Issue of Biomedical Beat
	Cool Video: How Bee Venom Toxin Kills Cells A new video, starring the toxin in bee venom, might help scientists design new drugs to combat bacterial infections. The video, by Rice University biophysicist Huey Huang , condenses 6.5 minutes into less than a minute to show how the toxin, called melittin, destroys an animal or bacterial cell. What looks like a red balloon is an artificial cell filled with red dye. Melittin molecules are colored green and float on the cell’s surface like twigs on a pond. As melittin accumulates on the cell’s membrane, the membrane expands to accommodate it. In the video, the membrane stretches into a column on the left. When melittin levels reach a critical threshold, countless pinhole leaks burst open in the membrane. The cell’s vital fluids—red dye in the video—leak out through these pores. Within minutes, the cell collapses. Many organisms use such a pore-forming technique to kill attacking bacterial cells. This research reveals molecular-level details of the strategy, bringing pharmaceutical scientists a step closer to harnessing it in the design of new antibiotics. Post a comment
	Chemist Phil Baran Joins “Genius” Ranks as MacArthur Fellow As a newly appointed MacArthur Fellow, Phil Baran  is now officially a genius. The MacArthur award recognizes “exceptionally creative” individuals who have made significant contributions to their field and are expected to continue doing so. Baran, a synthetic organic chemist at Scripps Research Institute in La Jolla, Calif., was recognized today for “inventing efficient, scalable, and environmentally sound methods” for building, from scratch, molecules produced in nature. Many of these natural products have medicinal properties. Baran has already concocted a host of natural products, including those with the ability to kill bacteria or cancer cells. In addition to emphasizing the important pharmaceutical applications of his work, Baran embraces its creative aspects: “The area of organic chemistry is such a beautiful one because one can be both an artist and an explorer at the same time,” he said in the MacArthur video interview . Post a comment Caption: When Baran’s research team succeeds in synthesizing an important natural product, the group sometimes celebrates with a cake decorated with a two-dimensional structure of the molecule. This molecule, stephacidin B, was isolated from a fungus and has anticancer properties. See images of other Baran lab cakes .
	Protein May Help Reduce Intestinal Injury Gail Besner of Nationwide Children’s Hospital and her research team recently found out how the HB-EGF growth factor protein could potentially aid the development of treatments for a number of conditions. Using model systems in two separate studies, the scientists discovered that HB-EGF could protect the intestines from injury by stimulating cell growth and movement and by decreasing substances formed upon intestinal injury that worsen the damage. They also showed that administration of mesenchymal stem cells could further shield the intestines from injury. Future treatments involving a combination of HB-EGF and stem cells could, for example, help cancer patients sustain fewer intestinal injuries resulting from radiation therapy. Post a comment This work also was funded by NIH’s National Cancer Institute. Caption: HB-EGF has the potential to protect the intestines (magnified here) from different types of injury. Credit: National Center for Microscopy and Imaging Research.
	How Some Bacteria Colonize the Gut Have you ever felt that your gut was trying to tell you something? The guts of germ-free mice have told scientists a few new things about our resident microorganisms. By studying a genus of bacteria called Bacteriodes that live in the gastrointestinal tract, Sarkis Mazmanian of the California Institute of Technology discovered how Bacteriodes species stake their claim in a mouse’s gut. Mazmanian and his colleagues introduced different species of Bacteriodes into germ-free mice to learn how the microbes competed and found that most of them peacefully co-existed. However, when microbes of a species that was already present were introduced, they couldn’t take up residence. Further investigation revealed that Bacteriodes species, due to a set of specific genes, can live in tiny pockets or “crypts” of the colon, where they are sheltered from antibiotics and infectious microbes passing through. Understanding how these microorganisms colonize could help devise ways to correct for abnormal changes in bacterial communities that are associated with disorders like inflammatory bowel disease. Post a comment This work also was funded by NIH’s National Institute of Diabetes and Digestive and Kidney Diseases. Caption: A section of mouse colon with gut bacteria (green) residing within a protective pocket. Credit: S. Melanie Lee, Caltech; Zbigniew Mikulski and Klaus Ley, La Jolla Institute for Allergy and Immunology.
	Making Strides in Genomic Engineering of Human Stem Cells Human pluripotent stem cells (hPSCs) can multiply indefinitely and give rise to virtually all human cell types. Manipulating the genomes of these cells in order to remove, replace or correct specific genes holds promise for basic biomedical research as well as medical applications. But precisely engineering the genomes of hPSCs is a challenge. A research team led by Erik Sontheimer of Northwestern University and James Thomson of the Morgridge Institute for Research at the University of Wisconsin-Madison developed a technique that could be a great improvement over existing, labor-intensive methods. Their approach uses an RNA-guided enzyme from Neisseria meningitidis bacteria—part of a recently discovered bacterial immune system—to efficiently target and modify specific DNA sequences in the genome of hPSCs. The technique could eventually enable the repair or replacement of diseased or injured cells in people with some types of cancer, Parkinson’s disease and other illnesses. Post a comment This work also was funded by NIH’s National Center for Advancing Translational Sciences. Caption: Genetically engineered human stem cells hold promise for basic biomedical research as well as for regenerative medicine. Credit: Jeff Miller, University of Wisconsin-Madison.
	Meet Galina Lepesheva Field: biochemistry Works at: Vanderbilt University, Nashville, TN Born, raised and studied in: Belarus To unwind, she: reads, travels, spends time with her family Galina Lepesheva knows that kissing bugs are anything but romantic. When the lights get low, these blood-sucking insects begin feasting—and defecating—on the faces of their sleeping victims. Their feces are often infected with a protozoan (a single-celled, eukaryotic parasite) called Trypanosoma cruzi that causes Chagas disease. Lepesheva has developed a compound that might be an effective treatment for Chagas. She has also tested the substance, called VNI, as a treatment for two related diseases—African sleeping sickness and leishmaniasis. Read more | Post a comment
	NIH Director Blogs About NIGMS-Funded Research Within the last few weeks, NIH Director Francis Collins has blogged about several findings that NIGMS helped fund: the identification of a genetic link between hair color and melanoma risk and the solving of human folate receptor structures, which may aid the design of drugs for cancer and inflammatory diseases like rheumatoid arthritis and Crohn’s disease. Both advances are excellent examples of the value and impact of basic research. Want more examples? Check out Curiosity Creates Cures! Post a comment
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