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 SRU Professor Researches How Frogs Freeze -- and Survive 



Dec. 21, 2004

Contact: Gordon Ovenshine; 724-738-4854;



SLIPPERY ROCK, Pa. – Picture an ice cube. Paint it blue-gray and you’ve got the gray treefrog in winter, says Dr. Jack Layne, a Slippery Rock University biology professor whose freeze-thaw research with frogs shows potential application to human organ transplants.

Layne studies how certain species of frogs freeze during winter, becoming so solid their hearts stop, and then thaw back to normal, able to reproduce in the spring.

Everyone’s heard of freezing to death. But for the gray treefrog and three other species Layne studies, the term doesn’t apply. “It’s just pretty amazing to see one frozen,” he says. “You would look at it and think it was dead. But it’s not.”

A “freeze tolerance” expert, Layne froze 24 frogs at his SRU lab this month in order to examine their tissues and organs. Working with students, he is studying how the organs survive the deep freeze and metabolize again after reviving. He sees potential applications to the preservation of human organs on their way to transplant patients.

If doctors could find a way to freeze and thaw some organs, it could extend the shelf life or organs for transplants, he says. Currently, doctors pack organs on ice after removal but they can’t be frozen because of potential damage to cells.

 Layne expects his research to be published this spring in scientific and medical journals read by those who study human tissue preservation. Some of his discoveries could yield clues on discovering a means for freezing human organs.

           Layne, who has published 50 papers on freeze tolerance, says four species of frogs freeze and survive: the wood frog, gray treefrogs, spring peepers and chorus frogs. All four live in southwestern Pennsylvania.

           Outdoors, the frogs hide themselves barely underground when the temperature drops below 32 degrees. Ice invades the frog’s arteries and its heart stops.

           Layne says the frogs survive because their cells are protected by a natural antifreeze that prevents excessive ice buildup in body tissues. The chemicals that do this job, glucose and glycerol, are in the bodies of all animals but freeze-tolerant frogs have these chemicals at levels that may be hundreds of times higher than in people.

When the temperature warms, the frogs thaw in about 12 hours, reviving as if coming out of a coma, then hop away unharmed. The reproduce in late March or early April, Layne says. Their emergence from hibernation allows tadpoles to take advantage of temporary ponds.

Editor’s note: University Public Relations has digital photographs of Layne’s frozen frogs.



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