In the News
Ebola Traced to Bats
Scientists may have located the long-sought natural reservoir of the
deadly Ebola virus. After combing through 1,000 species, a team
working in Gabon and the Republic of Congo isolated the virus in
three species of fruit bats, which are eaten by people in Central
Africa. Genetic traces turned up in 22.6 percent of the bats tested,
but the virus produced no symptoms in the infected bats, presumably
allowing them to spread the disease efficiently. Ebola's cycles of
emergence and disappearance have intrigued infectious disease
specialists. The new study does not nail down the bats as Ebola's
prime nesting spot between outbreaks—certainty would require
scientists to plot all points on the natural cycle of the
disease—but it does paint the bats as the best candidate yet.
Leroy, E. Fruit bats as reservoirs of Ebola virus. Nature
438:575–576 (December 1).
Obscured Starlight Defines Charon
Last summer, Pluto's moon Charon blocked light from a distant
star and in the process lifted itself out of obscurity. An
international team of astronomers were ready with three telescopes
locked in to catch the momentary eclipse, called a stellar
occultation. From that triangulated view of what happened to the
starlight as it passed around Charon's edge, the astronomers
determined many details about the moon. For instance, Charon is some
1,200 kilometers across, or about half Pluto's size. Its density is
1.71 times that of water, meaning close to half of its icy mass
consists of rock. The light also suggested that Charon has the same
atmosphere as Pluto, backing up the idea that Pluto and its three
moons coalesced as a system when two objects collided.
Sicardy, B., et al. Charon's size and an upper limit on
its atmosphere from a stellar occultation. Nature
439:52–54 (January 5) .
Catching Cancer's Spread
Cancers orchestrate the movement of bone marrow cells, then tap them
for the oxygen and other nutrients that power metastasis, according
to a study on mice. The finding answers key questions about how
tumor cells take up residence in other parts of the body. Cellular
envoys—normal bone marrow cells pressed into pernicious action
by tumor cells—prime the organ in which the tumor cells will
implant and turn into full-blown cancer. Once that colonization of
another organ has occurred, cancer is extremely difficult to
eradicate. New treatments might be developed by tracking the
movement of the envoy cells which provide a map of metastasis targets.
Rafii, S., and Lyden, D. VEGFR1-positive haematopoietic bone
marrow progenitors initiate the pre-metastatic niche.
Nature 438:820–827 (December 8).
Snails Hasten Marsh Grass Die-Off
In the last five years, Louisiana and South Carolina have lost
thousands of acres of salt marsh, the vital coastal wetlands that
filter pollutants, blunt the force of storms and serve as nurseries
for marine life. Marsh ecologists had blamed the die-off on
salt-stressed soil, but now another culprit has come to light:
snails. Typically content to live around the edges of a marsh,
munching on dead grasses and fungus, snails quickly changed their
grazing habits once the salt marshes became stressed by drought.
Huge numbers of them colonized the drier ground, eating large swaths
through the grasses. Ecologists who tracked the occurrence contend
more marshes could be subjected to the snails' altered eating habits
as climate change–related droughts become more frequent.
Silliman, B. R., et al. Drought, Snails, and
Large-Scale Die-Off of Southern U.S. Salt Marshes. Science
Skyscraper Causes Earthquakes?
Taipei 101 juts more than 500 meters up into the sky, making it the
tallest building in the world. And it's not just tall: The structure
is big-boned and immense, weighing 700,000 tons. A Taiwanese
geologist has claimed that the behemoth exerts so much pressure on
the ground that it has triggered two earthquakes and may have
reopened an ancient fault. Before construction, the Taipei basin
averaged about one micro-quake, of less than magnitude 2.0, per
year. But during the building's construction period that number
increased to about two micro-quakes per year. Since the building was
completed in 2004, two temblors large enough to be felt, of
magnitudes 3.8 and 3.2, have struck directly beneath 101.
Ironically, the hybrid of concrete and steel used in part to protect
the building from earthquakes may help to create them.
Lin, Cheng-Horng. Seismicity increase after the construction of
the world's tallest building: An active blind fault beneath the
Taipei 101. Geophysical Research Letters 32:L22313
Plucking Gene Makes Mice More Plucky
Call it addition through subtraction: Laboratory mice got a full
dose of courage after scientists took from them one simple gene.
Fear is fundamental, cruising along similar neurological pathways in
all mammals. Specifically, it takes hold in the amygdala, a
primitive little region of the brain that becomes hyperactive when
the going gets tense. Working in the amygdala, scientists found
heavy concentrations of a protein called stathmin; that protein was
not abundant elsewhere in the brain. So they genetically engineered
the stathmin gene out of a line of mice. Those mice showed
significantly less caution than a control group in two different
experiments. This result suggests that the stathmin protein might
play a role in the formation of unconscious memory and the fears
those memories create, which are filed in the amygdala.
Shumyatsky, G. Stathmin, a Gene Enriched in the
Amygdala, Controls Both Learned and Innate Fear. Cell
123:697–709. (November 18).