X-Message-Number: 13187
From: "Igor Artyuhov" <>
Subject: Humans have hybernation genes
Date: Thu, 3 Feb 2000 13:54:58 +0300

Source: UniSci (Daily University Science News) 02-Feb-2000

Learning How Animals Hibernate Can Help Humans

Each winter, hibernating animals perform one of the great physiological
marvels of the natural world. Burrowed in their dens, they survive months of
bitter cold without food by lowering their heart rates, metabolism and body
temperatures to levels that, in humans and other nonhibernating mammals,
would be fatal.
Scientists have long understood why animals hibernate. But how they perform
this amazing transformation -- exactly which genes control its onset in
autumn and its reversal come spring -- has largely remained a mystery.

Now, thanks to a pioneering five-year study by North Carolina State
University geneticists, the pieces of that genetic puzzle are starting to
come together.

Dr. Matthew Andrews and his research team have identified and mapped two
genes for enzymes that play important roles in hibernation in ground
squirrels, and have discovered that these genes are nearly identical to ones
found in nonhibernating mammals, including humans.

Because the genes are found in all mammals, not just in species that
hibernate, the study's findings have implications far beyond the field of
zoology, Andrews says.

"If we can identify the enzymes responsible for preserving organs, reducing
glucose consumption and maintaining muscle tone during an extreme state like
hibernation, physicians could use that knowledge to develop new strategies
for prolonging the 'shelf life' of human organs intended for transplants or
for helping humans suffering from starvation, muscle atrophy, hypothermia
and hypoxia," he explains.

One of the genes identified by Andrews and his research team controls the
production of pancreatic triglyceride lipase (PL), an enzyme that breaks up
triglycerides -- stored fatty acids -- and converts them into usable fats
for fuel in the hibernating ground squirrels.

The second gene encodes the production of pyruvate dehydrogenase kinase
isozyme 4 (PDK-4), an enzyme that is triggered during times of starvation
and helps conserve the body's stores of glucose. Both genes are expressed in
the squirrels' hearts at or just before the onset of hibernation.

Andrews' findings also may be of interest to evolutionary biologists. If
hibernation is controlled by the differential expression of existing
mammalian genes, as the research suggests, then the identification of these
genes could provide insight into how other mammals could adapt (or how, long
ago, their ancestors did adapt) to extreme environmental changes.

In the future, they might even help scientists safely induce a
hibernation-like state in astronauts during long-term space travel.

Andrews first reported the identification of the two genes in the
Proceedings of the National Academy of Sciences in 1998. Since then, he and
his team have mapped the genes, documented more fully how and when they're
turned on in hibernating ground squirrels, and how this differs from their
expression in nonhibernating mammals. (Pancreatic lipase (PL), for instance,
is usually expressed in the pancreas of nonhibernating mammals, not the

Further studies are being conducted on both summer-active and hibernating
animals to identify and isolate additional gene sequences.

The study is funded by the North Carolina Biotechnology Center and the U.S.
Army Research Office. - By Tim Lucas

[Contact: Dr. Matthew T. Andrews (  ), Tim Lucas

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