SCIENCE TIP SHEET June 1999
Contacts: Karen Young Kreeger [email protected] or Franklin Hoke (215) 662-2560
Philadelphia, Pa. -- Below are three story ideas based on ongoing research at the University of Pennsylvania Medical Center.
DNA Catapult Springs Recombination Reaction Forward: Using X-ray diffraction, a research team led by Gregory Van Duyne, PhD, assistant professor of biochemistry and biophysics, showed that a protein used in the splicing of genetic material contorts DNA in ways never seen before. The recombination reaction - the process of cutting and chemically piecing together genetic material from different sources - is carried out by Cre recombinase. This enzyme helps two double strands of DNA exchange sequences of the genetic code by a chemical cutting and pasting operation. The Cre enzyme does this by pulling the nucleic bases that make up the rungs of the DNA double-helix ladder into positions that allow for easier breaking of the bonds holding the DNA molecules together. The team's findings appear in the June 22 issue of the Proceedings of the National Academy of Sciences. An illustration of the recombination reaction appears on the issue's cover. From previous experiments, the researchers know
Possible Driver for Breast Cancer Metastasis Discovered: Acting as a chemical attractant, the hormone prolactin stimulates the coordinated movement of breast cancer cells in culture, according to new findings from researchers at the University of Pennsylvania Medical Center. Using time-lapse video microscopy, the scientists were able to show that breast cancer cells will move toward a prolactin source in cell culture and even cross a membranous barrier to reach the source. Also revealed was that the prolactin-induced motion of breast cancer cells is accompanied by corresponding changes in the cellular machinery responsible for motion. The experiments demonstrated that prolactin triggers the formation of actin filaments and lamellipodia, features that can be thought of as the muscles and feet, respectively, of the cell. Prolactin normally functions to prompt the growth and maturation of breast tissues as a prelude to lactation during pregnancy. Data from several laboratories, however, i
Less is More in Short-term Memory Triage: Using functional MRI (fMRI) as a brain-imaging tool, Bart Rypma, PhD, a postdoctoral fellow in the department of neurology, found that the brain region that governs short-term memory is divided into distinct parts with each part serving a separate purpose. The top, or dorsal, part of this region -- the prefrontal cortex -- manipulates incoming information for efficient storage by the bottom, or ventral, part, which stores the information for future use. "For example, if someone tells you a list of places you need to visit on an errand trip, the ventral prefrontal cortex would be responsible for just remembering those locations -- the hardware store, the grocery store, the locksmith," explains Rypma. "While the ventral prefrontal cortex is busy just holding onto the information, the dorsal prefrontal cortex would be busy planning the most efficient route of travel." Rypma and Mark D'Esposito MD, assistant professor of neurology, describe their w
The University of Pennsylvania Medical Center's sponsored research and training ranks second in the United States based on grant support from the National Institutes of Health, the primary funder of biomedical research and training in the nation -- $201 million in federal fiscal year 1998. In addition, the institution continued to maintain the largest absolute growth in funding for research and training among all 125 medical schools in the country since 1991. News releases from the University of Pennsylvania Medical Center are available to reporters by direct e-mail, fax, or U.S. mail, upon request. They are also posted electronically to the medical center's home page (http://www.med.upenn.edu), to the electronic news service Newswise (http://www.newswise.com).
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