National Academy of Sciences
Two Johns Hopkins scientists were among 72 U.S. scientists elected today to membership in the National Academy of Sciences at the organization's 142nd annual meeting, held in Washington, D.C.
Peter Devreotes, Ph.D., director and professor of cell biology at the Johns Hopkins School of Medicine's Institute for Basic Biomedical Sciences, and Charles Bennett, Ph.D., a professor in the Henry A. Rowland Department of Physics and Astronomy at the Krieger School of Arts and Sciences, join 18 other Johns Hopkins faculty members currently in the Academy, an honorary society that advises the government on scientific matters.
Devreotes's research focuses on understanding how cells sense their surroundings and move in response to what they detect. Even though cells don't have noses, brains or muscles, they sense and move toward various molecules much like a person might smell warm cinnamon rolls and hunt for them. When an attractive chemical is added to one side of the dish and is detected by the cell, the cell begins to rearrange its membrane so that "pseudopods" — literally false feet — can form and pull the cell along.
By studying a single-celled amoeba, Devreotes has been identifying the genes and proteins involved in sensing molecules and in forming pseudopods. A tricky aspect of the cells' sensing ability is that in order to move toward the source of the molecule, each cell has to be able to detect very tiny differences in how much of the molecule might be in front, behind, to the right and to the left.
The first step in sensing the molecule is its binding to docking points, or receptors, scattered throughout the cell's surface. In 1988, Devreotes cloned the first receptors involved in cell attraction. In 2001, he and his colleagues reported in the journal Science that the receptors remain spread out and bind and release the attractant molecules over the whole cell, even though pseudopods protrude only from the front.
Much of his lab's work has focused on understanding how the cell membrane is softened to allow formation of the pseudopods. Over the years, he and his colleagues have discovered that a molecule called PIP3 is critical to this process. In the "front" of the cell, an enzyme accumulates that makes PIP3, while the back of the cell is occupied by an enzyme that breaks down PIP3.
Just last month, the researchers reported that the same enzymes — and PIP3 — are involved in allowing the two halves of a dividing cell to move away from each other, suggesting that the enzymes or other steps in the process might be suitable targets for slowing or stopping cell division. The finding might eventually lead to a new way to attack cancer, which is characterized by uncontrolled cell division.
Devreotes received his B.S. in physics in 1971 from the University of Wisconsin, earned a Ph.D. in biophysics from Johns Hopkins in 1977, and then conducted postdoctoral work at the University of Chicago.
He returned to Johns Hopkins as an assistant professor in 1980. After moving through the ranks of the Department of Biological Chemistry, he was named director of the Department of Cell Biology in 2000. Devreotes has carved a name for himself as a scientist, administrator and teacher. He is author or co-author of more than 180 scientific publications.
Bennett, a cosmologist whose interests include the origins and fate of the universe, also was awarded the Henry Draper Medal at the NAS meeting on Monday. The academy awards the medal once every four years to an honoree who has made significant contributions to astronomical physics.
Bennett came to Johns Hopkins this past Jan. 1 from his position as a senior scientist for experimental cosmology at NASA's Goddard Space Flight Center. He is principal investigator of the Wilkinson Microwave Anisotropy Probe (WMAP), a NASA Explorer mission aimed at determining precisely the age, composition and curvature of the universe.
WMAP measures the temperature of cosmic background radiation, the oldest light in the universe and a remnant of the Big Bang. Using WMAP, Bennett's team took the universe's first-ever, detailed, full-sky "baby picture" in microwave light from 379,000 years after the Big Bang.
Using WMAP, Bennett says, astronomers are able to determine what the universe looked like in its very early years. Combining that data with results on the more recent universe from projects like the Sloan Digital Sky Survey and the Hubble Space Telescope pinpointed 13.7 billion years as the age of the universe and established the existence and importance of "dark matter" and the even more mysterious "dark energy." The results were recognized by Science as a 2003 "Breakthrough of the Year." Determining the exact nature of dark energy, which scientists believe is causing the universe to expand at ever-increasing rates, remains a key goal of physicists and astronomers.
Bennett graduated in 1978 from the University of Maryland, College Park, cum laude and with high honors in astronomy. He earned his Ph.D. in physics from the Massachusetts Institute of Technology in 1984.
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