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 Why do animals fight members of other species?
24.04.2015 | University of California - Los Angeles

nachricht Is a small artificially composed virus fragment the key to a Chikungunya vaccine?
24.04.2015 | Paul-Ehrlich-Institut - Bundesinstitut für Impfstoffe und biomedizinische Arzneimittel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fast and Accurate 3-D Imaging Technique to Track Optically-Trapped Particles

KAIST researchers published an article on the development of a novel technique to precisely track the 3-D positions of optically-trapped particles having complicated geometry in high speed in the April 2015 issue of Optica.

Daejeon, Republic of Korea, April 23, 2015--Optical tweezers have been used as an invaluable tool for exerting micro-scale force on microscopic particles and...

Im Focus: NOAA, Tulane identify second possible specimen of 'pocket shark' ever found

Pocket sharks are among the world's rarest finds

A very small and rare species of shark is swimming its way through scientific literature. But don't worry, the chances of this inches-long vertebrate biting...

Im Focus: Drexel materials scientists putting a new spin on computing memory

Ever since computers have been small enough to be fixtures on desks and laps, their central processing has functioned something like an atomic Etch A Sketch, with electromagnetic fields pushing data bits into place to encode data.

Unfortunately, the same drawbacks and perils of the mechanical sketch board have been just as pervasive in computing: making a change often requires starting...

Im Focus: Exploding stars help to understand thunderclouds on Earth

How is lightning initiated in thunderclouds? This is difficult to answer - how do you measure electric fields inside large, dangerously charged clouds? It was discovered, more or less by coincidence, that cosmic rays provide suitable probes to measure electric fields within thunderclouds. This surprising finding is published in Physical Review Letters on April 24th. The measurements were performed with the LOFAR radio telescope located in the Netherlands.

How is lightning initiated in thunderclouds? This is difficult to answer - how do you measure electric fields inside large, dangerously charged clouds? It was...

Im Focus: On the trail of a trace gas

Max Planck researcher Buhalqem Mamtimin determines how much nitrogen oxide is released into the atmosphere from agriculturally used oases.

In order to make statements about current and future air pollution, scientists use models which simulate the Earth’s atmosphere. A lot of information such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

HHL Energy Conference on May 11/12, 2015: Students Discuss about Decentralized Energy

23.04.2015 | Event News

“Developing our cities, preserving our planet”: Nobel Laureates gather for the first time in Asia

23.04.2015 | Event News

HHL's Entrepreneurship Conference on FinTech

13.04.2015 | Event News

 
Latest News

Electrons Move Like Light in Three-Dimensional Solid

24.04.2015 | Materials Sciences

Connecting Three Atomic Layers Puts Semiconducting Science on Its Edge

24.04.2015 | Materials Sciences

Understanding the Body’s Response to Worms and Allergies

24.04.2015 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>