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(Bio) Hibernation: Break in Hibernation Help Fight Bugs

 
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adedios
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PostPosted: Wed Aug 16, 2006 9:59 am    Post subject: (Bio) Hibernation: Break in Hibernation Help Fight Bugs Reply with quote






Penn State
16 August 2006

Breaks in hibernation help fight bugs

A habit in some animals to periodically wake up while hibernating may be an evolutionary mechanism to fight bacterial infection, according to researchers at Penn State. The finding could offer an insight into the spread and emergence of infectious disease in wildlife, and has potential implications for human health.

Many warm-blooded animals slip into an inert sleep-like state as part of a unique strategy to get past harsh winters when food supplies are low and the need for energy to stay warm is high. The immune system is in sleep mode as well.

"The production of antibodies, and white blood cells is stopped. Basically all cell reproduction shuts off," says Angela Luis, a doctoral candidate in ecology at Penn State's Center for Infectious Disease Dynamics.

However, animals regularly snap out of their torpor, and become fully active. But such sudden breaks from slumber eat into much of the animal's stored energy reserves, and it is not fully clear why the animals need to wake up, and how often

Some scientists think the answer lies in bacterial infections that could run rampant in the face of an immune system that is essentially asleep.

"Animals cannot tell when they need to wake up, or if they are infected," says Luis. If the animals hibernate for long they risk serious infection, she says, while waking up frequently wastes precious energy, and could prove fatal as well.

In other words, animals with an optimal time of torpor will win out over others, says Luis, who presented her findings at the 91st annual meeting of the Ecological Society of America.

Luis and her colleagues used a simple mathematical model that mimicked the growth of bacteria such as E. coli and Salmonella in European ground squirrels, and how it affected their torpor patterns in relation to temperature.

Microbial growth depends on temperature. Most bacteria grow faster when it is warm and much slower when it is cold. For animals exposed to Salmonella, which multiplies rapidly in warm temperature, a regular break in hibernation would be an important adaptation to combat the germs, when experiencing a warmer winter. However, Salmonella doesn't thrive at very low temperatures, so when animals experience a particularly cold winter, these breaks wouldn't be crucial.

But if the animals were exposed to certain pathogens that thrive at low temperatures, like some E. coli, the animals would still have to regularly break their hibernation to ensure protection at all temperatures, Luis explains.

"Our model, which is confirmed by field data, shows that torpor patterns generally seen in some hibernating animals may be an evolutionary adaptation to help protect them from bacteria that grow well in low temperatures," says Luis.

The researchers suggest that an understanding of how pathogens interact with their hibernating hosts could provide valuable insight into the spread and emergence of zoonotic diseases.

*************************************************************

Questions to explore further this topic:

What is hibernation?

http://library.thinkquest.org/.....ernate.htm
http://www.yptenc.org.uk/docs/.....ation.html
http://www.nk2.psu.edu/naturet.....nation.htm
http://dnr.state.il.us/Lands/e.....nit2_2.pdf
http://www.wolf-ridge.org/what.....ation.html
http://www.earthsky.com/earthc.....e=20021231

Examples of hibernators

http://www.bbc.co.uk/nature/re.....ndex.shtml

What is torpor?

http://library.thinkquest.org/TQ0312800/torpor.htm

What is estivation?

http://library.thinkquest.org/.....vation.htm

What is diapause?

http://library.thinkquest.org/.....apause.htm

Secrets of Hibernation

http://www.pbs.org/wgbh/nova/s.....ation.html

Can humans hibernate?

http://www.earthsky.com/shows/.....e=20031010
http://www.ibiblio.org/astrobi.....e=future03
http://www.livescience.com/hum.....ation.html
http://service.spiegel.de/cach.....46,00.html
http://www.space.com/scienceas.....41012.html

Recent news articles on hibernation

http://researchnews.osu.edu/archive/hibsqrl.htm
http://topics.nytimes.com/top/.....index.html

What is the immune system?

http://www.paete.org/forums/viewtopic.php?t=1121

What are bacteria?

http://users.rcn.com/jkimball......teria.html
http://www.paete.org/forums/viewtopic.php?t=914
http://student.ccbcmd.edu/cour.....index.html

What are bacterial infections?

http://www.mayoclinic.com/health/germs/ID00002
http://www.niaid.nih.gov/publications/microbes.htm
http://www.lef.org/protocols/i.....ion_01.htm
http://www.healthinsite.gov.au.....Infections
http://www.mic.ki.se/Diseases/C01.html

GAMES

http://library.thinkquest.org/TQ0312800/game.htm


Last edited by adedios on Sat Jan 27, 2007 3:51 pm; edited 2 times in total
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adedios
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Location: Angel C. de Dios

PostPosted: Sat Jan 27, 2007 9:06 am    Post subject: Reply with quote

Week of Jan. 27, 2007; Vol. 171, No. 4 , p. 56

Perchance to Hibernate
Can we tap a dormant capacity to downshift our metabolism?
Ben Harder

This time of year, the wilds of North America are relatively quiet. The black bears that usually patrol the woods seem to have vanished. Many bat species are nowhere to be found, at least not by the causal observer. The same is true of ground squirrels and chipmunks. They are hidden away—hibernating.

For the full article:

http://sciencenews.org/articles/20070127/bob9.asp
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adedios
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PostPosted: Tue Apr 24, 2007 10:39 am    Post subject: Study shows hibernating bears conserve more muscle strength Reply with quote

University of Chicago Press Journals
24 April 2007

Study shows hibernating bears conserve more muscle strength than humans on bed rest do

A fascinating new study from the May/June 2007 issue of Physiological and Biochemical Zoology quantifiably measures the loss of strength and endurance in black bears during long periods of hibernation. T.D. Lohuis (Alaska Department of Fish and Game) and his coauthors find that black bears in hibernation lose about one-half as much skeletal muscle strength as humans confined to bed rest for similar periods of time do.

"Fasting, unweighting, or immobility results in compromised muscle function," explain the authors. They continue, "Because bears are confined and anorexic for several months during winter but can still retain muscle protein and display sustained activity if disturbed, we measured skeletal muscle strength, fatigue resistance, and in vivo contractile properties of intact muscles in bears within their natural dens."

Adapting a system used for the evaluation of neuromuscular disease progression in humans, the researchers tested black bears from Middle Park, Colorado, both early and late in the hibernation cycle. After sampling, bears were placed back in their den, and the entrance was covered with pine boughs and snow.

The researchers found that after 110 days of anorexia and confinement in the den, bears lost about 29% of their muscle strength. In comparison, humans on a balanced diet but confined to bed for 90 days have been reported to lose 54% of their strength. Other studies have shown that human astronauts in a weightless environment lose 9%–11% of their strength during a 17-day spaceflight.

Black bears also sustained only a moderate loss of fatigue resistance, the researchers found: "After 110 days of fasting and limited mobility imposed by denning, bears still exhibited a fatigue profile similar to that of healthy, active, fed humans."

In contrast to other, smaller hibernating mammals such as prairie dogs and squirrels, black bears also conserved muscle protein and size. The researchers found no loss in the fiber cross-sectional area of the bears’ thighs or calves, a drop of only about 10% in the protein content of the thighs, and no reduction in protein content in the calves or quadriceps of the bears.

"Bears in this study exhibited remarkable conservation of muscle function," write the authors. "In spite of a size difference of almost three orders of magnitude and a 30 degree Celsius difference in torpor body temperature, the black bear may conserve muscle function to the extent of or perhaps better than small-mammal hibernators."

Since 1928, Physiological and Biochemical Zoology has presented current research in environmental, adaptational, and comparative physiology and biochemistry. Original research results represent a variety of areas, including thermoregulation, respiration, circulation, osmotic and ionic regulation, environmental acclimation, evolutionary physiology, and metabolic physiology and biochemistry.

###
T. D. Lohuis, H. J. Harlow, T. D. I. Beck, and P. A. Iaizzo, "Hibernating Bears Conserve Muscle Strength and Maintain Fatigue Resistance." Physiological and Biochemical Zoology: 80:3.
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adedios
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Joined: 06 Jul 2005
Posts: 5060
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PostPosted: Thu May 03, 2007 1:19 pm    Post subject: Astronauts Get a Tip from Hibernating Bears Reply with quote

Astronauts Get a Tip from Hibernating Bears

By Jeanna Bryner
Staff Writer
posted: 03 May 2007
12:12 pm ET

WASHINGTON—Stretch. Yawn. Ahhh. Black bears are just waking up from their winter snooze and have peeped out of their dens. And they are surprisingly fit.

Bears conk out for up to seven months during the Wisconsin winters, a snooze that would turn a human's muscles into Jell-O. But when nature's alarm clock signals it's time to awaken from hibernation, black bears have just as much muscle mass as when they tucked themselves in for the deep slumber, a new study finds.

The results were presented here this week at a meeting of the American Physiological Society as part of annual Experimental Biology meeting.

The discovery could ultimately help astronauts and the bed-ridden maintain their skeletal muscles. In fact, the research was initially spurred by astronauts who had trouble recovering after a trip to space.

For the full article:

http://www.livescience.com/ani.....ators.html
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