Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Alaska frogs reach record lows in extreme temperature survival

23.07.2014

Freezing and thawing might not be good for the average steak, but it seems to help wood frogs each fall as they prepare to survive Alaska’s winter cold.

“Alaska wood frogs spend more time freezing and thawing outside than a steak does in your freezer and the frog comes back to life in the spring in better shape than the steak,” said Don Larson, University of Alaska Fairbanks graduate student and lead author on a recent paper demonstrating that freeze tolerance in Alaska wood frogs is more extreme than previously thought.

Although wood frogs are well-studied freeze-tolerant amphibians, Larson’s research is believed to be the first to examine the frogs under natural conditions.

In subarctic Interior Alaska, wood frogs overwinter in the ground covered by duff and leaf litter, creating a hibernacula, where temperatures can remain below freezing for more than six months with minimum temperatures of minus four (minus 20 Celsius).

Tracking wood frogs to their natural hibernacula, and using a fenced hibernacula in the Biological Reserve north of the UAF campus, Larson and co-author Brian Barnes, director of the UAF Institute of Arctic Biology and an expert in cold-climate physiology, wanted to know how cold and how long Alaska’s wood frogs could survive in their natural habitat.

“Imagine what happens when you suck on a freeze pop,” said Larson. “After you’ve sucked out all the sweet stuff, you’re left with just ice. That’s what happens to cells when they freeze. As ice formation pulls the water out of cells, the cells desiccate or dry out and eventually die.”

Frogs prevent this freeze-pop effect by packing their cells with glucose (a kind of sugar) that reduces drying and stabilizes cells, a process scientists call cryoprotection.             

“Concentrating sugar inside the cell helps balance the concentration of salts outside the cell that occurs as ice forms,” said Barnes. “Less water leaves the cell than if sugar was not present and sugar and other cryoprotectants are thought to "hold" water inside the cell.”

The curious thing Larson discovered is that when wood frogs are outside in their natural environment they accumulate much higher concentrations of glucose in their tissues than do frogs frozen in the lab.

Glucose concentrations in the outside frogs were 13-fold higher in muscle tissue, 10-fold higher in heart tissue and 3.3-fold higher in liver tissue compared to lab-frozen frogs, as described in their paper published in the Journal of Experimental Biology.  

This extra protection enabled frogs to survive colder temperatures for a longer time than scientists previously thought, but Larson and Barnes wondered how they accumulated so much glucose?

Larson thinks the process that creates freezer burn on a frozen steak gives frogs the ability to survive being frozen at minimum temperatures below zero (minus 18 Celsius) for up to 218 days with 100 percent survival.

Frogs collected from sites in the Eastern U.S. and Canada have previously been shown to only survive being frozen for a few weeks and to no lower than about 19 degrees (minus 7.2 Celsius).

“In the field in early Autumn it’s freezing during the night, thawing slightly during the day, and these repeated freezing episodes stimulate the frogs to release more and more glucose,” Larson said. “It’s not warm enough for long enough for the frog to reclaim much of that glucose and over time it accumulates giving the frog more protection against cell damage.”

Lab-frozen frogs are held at a constant temperature and without the freeze-thaw cycles Larson observed in the wild and so the frogs made glucose only when they initially froze and that was that.

“Whether the extremes in freezing tolerance in Alaska frogs as compared to more southern populations are due to  patterns of temperature change during freezing or are due to genetic differences, and thereby represent  evolutionary change, awaits further study,” said Barnes.

The feats of freezing frogs are more than just a curiosity and may one day have application in the science of human organ transplantation.

“If science can figure out how to freeze human organs without damage it would allow more time to reach people in need of organs,” said Larson.

This research was funded by the National Science Foundation.

ADDITIONAL CONTACTS: Don Larson, djlarson@alaska.edu, 907-474-6067. Brian M. Barnes, bmbarnes@alaska.edu, 907-474-7649.

Marie Thoms | Eurek Alert!
Further information:
http://www.iab.uaf.edu/news/news_release_by_id.php?release_id=124

Further reports about: Alaska Arctic Biology Glucose Tracking damage environment freezer liver temperature

More articles from Life Sciences:

nachricht A Fluttering Accordion
04.08.2015 | Friedrich-Schiller-Universität Jena

nachricht Molecular Spies to Fight Cancer - Procedure for improving tumor diagnosis successfully tested
03.08.2015 | Helmholtz-Zentrum Dresden-Rossendorf

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Greenhouse gases' millennia-long ocean legacy

Continuing current carbon dioxide (CO2) emission trends throughout this century and beyond would leave a legacy of heat and acidity in the deep ocean. These...

Im Focus: Glaciers melt faster than ever

Glacier decline in the first decade of the 21st century has reached a historical record, since the onset of direct observations. Glacier melt is a global phenomenon and will continue even without further climate change. This is shown in the latest study by the World Glacier Monitoring Service under the lead of the University of Zurich, Switzerland.

The World Glacier Monitoring Service, domiciled at the University of Zurich, has compiled worldwide data on glacier changes for more than 120 years. Together...

Im Focus: Quantum Matter Stuck in Unrest

Using ultracold atoms trapped in light crystals, scientists from the MPQ, LMU, and the Weizmann Institute observe a novel state of matter that never thermalizes.

What happens if one mixes cold and hot water? After some initial dynamics, one is left with lukewarm water—the system has thermalized to a new thermal...

Im Focus: On the crest of the wave: Electronics on a time scale shorter than a cycle of light

Physicists from Regensburg and Marburg, Germany have succeeded in taking a slow-motion movie of speeding electrons in a solid driven by a strong light wave. In the process, they have unraveled a novel quantum phenomenon, which will be reported in the forthcoming edition of Nature.

The advent of ever faster electronics featuring clock rates up to the multiple-gigahertz range has revolutionized our day-to-day life. Researchers and...

Im Focus: Superfast fluorescence sets new speed record

Plasmonic device has speed and efficiency to serve optical computers

Researchers have developed an ultrafast light-emitting device that can flip on and off 90 billion times a second and could form the basis of optical computing.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Success 4.0 – Is Your Company Fit for the Future? New Series of Events for Executives

04.08.2015 | Event News

3rd Euro Bio-inspired - International Conference and Exhibition on Bio-inspired Materials

23.07.2015 | Event News

Clash of Realities – International Conference on the Art, Technology and Theory of Digital Games

10.07.2015 | Event News

 
Latest News

Siemens to modernize large sections of the Belgian railway network

04.08.2015 | Transportation and Logistics

Greenhouse gases' millennia-long ocean legacy

04.08.2015 | Earth Sciences

Cassiopeia's hidden gem: The closest rocky, transiting planet

04.08.2015 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>