OF
NOTE
getting estrogen therapy were having
about two hot flashes per day. However,
women taking the placebo or one of the
black cohosh treatments still experienced
on average four to five hot flashes daily,
the scientists report in the Dec. 19, 2006
Annals of Internal Medicine.
Because the women volunteered for the
trial, they “probably hoped there would
be an effect” from black cohosh, Newton
says. “If anything, that reinforces our finding.” —N.S.
BIOLOGY
Stem cells float in
amniotic fluid
Scientists have discovered a new type of
stem cell in the fluid that bathes fetuses in
the womb. These cells can grow into a variety of body tissues, the researchers report.
Scientists have long known that cells
from fetuses float in amniotic fluid. Such
cells are frequently used for genetic tests
to predict a baby’s health. However,
Anthony Atala of the Wake Forest University School of Medicine in Winston-Salem, N.C., and his colleagues wondered
whether some of the fetal cells in amniotic fluid are stem cells.
Using amniotic fluid drawn from expectant mothers when they had amniocentesis, the researchers searched for cells
with surface proteins that are typically
present on embryonic stem cells. The
researchers found that about 1 percent of
the cells had these markers.
Further investigation showed that the
cells with these embryonic stem cell proteins also had other proteins on their surfaces that are typically present on adult stem
cells. No other stem cell has been found to
contain both sets of markers, Atala notes.
Under certain conditions, the newly discovered cells develop into cartilage, muscle, heart, bone, liver, and other types of
tissue, the researchers report in the January Nature Biotechnology. Transplants of
the stem cells might eventually treat
patients who have diseased or damaged
tissues, says Atala. —C.B.
AGRICULTURE
Big footprints
There are surprisingly large hidden costs
to hot dogs, burgers, milk, and other animal
products, finds a new report entitled Live-
stock’s Long Shadow. Prepared by the
United Nations Food and Agricultural
Organization in Rome, the report notes that
animal agriculture is the second or third
biggest contributor to “the most serious
environmental problems, at every scale
from local to global.”
The report’s authors calculate that livestock production taps 8 percent of all
fresh water used by humanity, primarily
to irrigate feed crops. Farmed animals—
now 20 percent of the total mass of land
animals—are also edging out species and
cutting biodiversity. The report observes
that 30 percent of the land that these livestock now occupy once nurtured wildlife.
Livestock production is also having a
growing influence on climate. Animal
farming accounts for 18 percent of green-house-gas emissions, making it a bigger
contributor than transportation. For
instance, livestock are responsible for
9 percent of carbon dioxide releases associated with human activities, mostly as
woodlands are burned around the globe
for pastures or to create fields to grow feed.
Moreover, 37 percent of all human-induced
methane comes from livestock. Molecule-for-molecule, this major greenhouse gas
contributes 23 times as much to global
warming as carbon dioxide does.
The new report was not issued “simply
to blame” livestock managers, but to
encourage less-damaging practices, says
Samuel Jutzi, director of the Food and
Agricultural Organization’s animal program. Among his group’s recommendations: Calculate the cost of goods and services provided to animal agriculture by the
environment and pass them along to livestock farmers. Not doing so, the report
argues, fosters pollution and overex-ploitation of resources. —J.R.
SCIENCE & SOCIETY
Congress upgrades
fisheries protection
On Dec. 9, 2006, Congress reauthorized
the 30-year-old Magnuson-Stevens Act, a
law that sets rules for fishing and ocean
management. This is the law’s first wholesale revision since 1996.
Much has happened since then. Fisheries throughout the world are in trouble
(SN: 11/4/06, p. 291), and some species
not targeted for consumption are becoming unintended casualties of fishing fleets
(SN: 7/26/03, p. 59).
Among new features of the law, research
would be directed at getting better data
on those accidental catches, on the status
of fishery populations, and on the impact
of recreational fishing. Indeed, the law will
establish a new national program to register recreational fishing in marine coastal
waters and recreational fishing anywhere
for salmon and other fish that spend part
of their lives in both fresh and salt water.
The updated law also strengthens controls on illegal, unreported, and unregulated fishing, with the goal of ensuring that
other nations provide marine-resource protection that is similar to that in place for
fish in U.S. waters. For instance, the law
will require the secretary of commerce to
strictly define what would constitute violations of international agreements on
heavily fished species and on potentially
damaging fishing gear.
Although President Bush hadn’t signed
the reauthorization bill into law at press
time, he was expected to do so. The President issued a statement early last month
saying, “This bill embraces my priorities of
ending overfishing and rebuilding our
nation’s fish stocks.” —J. R.
BIOLOGY
Genes discovered
for sensing
carbon dioxide
Researchers have tracked down a pair of
genes that, together, seem responsible for
some insects’ ability to sense carbon dioxide. Because mosquitoes detect the gas to
home in on their next blood meal, a means
to block this sense could lead to more-effec-tive mosquito repellents.
To locate the carbon dioxide–sensing
genes, Leslie Vosshall of the Rockefeller
Institute in New York and her colleagues
worked with Drosophila melanogaster.
Other researchers had previously found
that carbon dioxide–sensing cells in this
fruit fly’s antennae express a gene known
as gustatory receptor 21a (Gr21a). Using
a genetic test, Vosshall’s team discovered
that these cells also express a related gene
known as Gr63a.
To see whether the two genes play a
role in carbon dioxide detection, the
researchers inserted them into fruit fly
neurons that normally respond to fruit
odors but not to carbon dioxide. When
the researchers placed both genes into
the neurons, the cells responded to carbon dioxide, but neither of the genes on
its own had that effect.
Vosshall and her colleagues also created
mutant flies missing Gr63a. These flies
didn’t respond to carbon dioxide.
A genetic-database search revealed that
mosquitoes have their own versions of
Gr21a and Gr63a. The researchers note
in the Jan. 4 Nature that if scientists find
chemicals that gum up either of the receptors encoded by those genes, those compounds might leave mosquitoes blind to
the carbon dioxide emitted by their targets. —C.B.
