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Anesthesia by day gives bees jet lag
By Susan Milius
A widely used anesthetic gives honeybees jet lag, but only if they’re knocked
out during the day.
Honeybees, as stand-ins for surgery
patients, confirm that a bout of the general anesthetic isoflurane acts directly
on the biological clock that governs body
rhythms, reports chronobiologist Guy
Warman of the University of Auckland
in New Zealand. Nighttime anesthesia hits the internal clock at a different
phase, when the drug effects don’t break
the rhythm, he and his colleagues report
May 1 in the Proceedings of the National
Academy of Sciences.
Warman doesn’t advise scheduling
all surgery at night as a result of the new
findings. “Then your anesthetist and
your surgeon are exhausted and more
likely to make errors,” he says.
Instead, the research has inspired him
and his colleagues to start developing
ways to keep the internal clock ticking
normally, perhaps by adding light therapy to surgery protocols.
Honeybees wearing tags to allow for
automated monitoring of arrivals and
departures from hives developed a ver-
sion of jet lag after daytime anesthesia.
Doctors have seen that people often
emerge from general anesthesia disoriented in time and may sleep fitfully
for a while afterward. To see whether
anesthesia itself causes the effects and
whether it does so by acting directly on
the underlying master clock, Warman
and his colleagues designed experiments
using honeybees. Honeybees are great
for testing effects on biological clocks,
Warman says, because their clock genes
are more similar to mammals’ than to
those of other insects studied so far.
Researchers trained bees to fly out of
their hives to visit an artificial flower for
sugar water. For the test, researchers
caught the bees as they buzzed in for a
sip and anesthetized them for six hours.
When the bees woke up and set off for
their hive again, they flew at the wrong
angle. Honeybees navigate in part by the
position of the sun, and their built-in
biological clock lets them correct course
for the sun’s movement across the sky
during the day. After anesthesia, though,
the bees made their “correction” as if the
time were hours earlier.
In a test inside the lab with no outdoor
cues, daytime anesthesia threw off the
usual activity patterns in the hive for
the next several days. But the researchers didn’t see a similar disruption to the
bees’ behavior and gene activity after
nighttime anesthesia.
Testing for clock effects in bees is a
good start because researchers could
control for most of the factors that can
confound results in human trials, says
neurobiologist Nancy Chamberlin of
Beth Israel Deaconess Medical Center
in Boston. “The results of this study
make the more difficult human studies
worth doing to see if there is a clinical
relevance or not,” she says.
FROM TOP: COUR TES Y OF G. WARMAN; © FLORIAN SCHULZ/ WWW.VISIONSOFTHEWILD.COM
Polar bears go way back
Polar bears might have originated about 600,000 years ago,
Frank Hailer of the Biodiversity and Climate Research Center
in Frankfurt and colleagues report April 20 in Science. Previous studies suggested that the species, Ursus maritimus,
emerged about 150,000 years ago. But those estimates were
based on genetic information from mitochondrial DNA, which
is passed down only through the maternal line. In the new
study, researchers studied nuclear DNA, inherited from both
parents, from 45 polar, brown and black bears. An earlier origin
for polar bears would mean the imperiled species probably
survived several glaciation and warming cycles. The population’s lack of genetic variation suggests that the warm phases
wiped out many bears, creating a genetic bottleneck. Added
to stresses such as pollution and hunting, today’s climate
change and resulting habitat loss might threaten the bears’
survival, Hailer says. — Rebecca Cheung
