Two Johns Hopkins professors were among 72 U.S.
scientists elected May 3 to membership in the National
Academy of Sciences at the organization's 142nd annual
meeting, held in Washington, D.C.
Peter Devreotes, director of the
Department of Cell Biology in the
School of Medicine's Institute for Basic Biomedical
Sciences, and Charles Bennett, a professor in the
Henry A. Rowland
Department of Physics and Astronomy in 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' 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 bachelor of science degree in
physics in 1971 from the University of Wisconsin, earned a
doctorate 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 last week. 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 on 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 Anistropy Probe, 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 doctorate in physics from MIT in
1984.