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5 December 2013 11:26 am ,
Vol. 342 ,
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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ScienceShot: The Secret of the Frozen Frogs
21 August 2013 6:00 pm
To call wood frogs hardy would be an understatement. The species (Rana sylvatica) can survive winter temperatures that freeze up to two-thirds of the water in their bodies. They endure this annual popsicle phase with help from cryoprotectants, substances circulating in their blood that lower the freezing point of their body fluids. New research shows that frogs at the northern limits of the species’ range are uniquely adapted to freezing. A team of zoologists collected wood frogs near Fairbanks, Alaska, and froze them to -16°C—a temperature that would kill frogs of the same species living in the midwestern United States. When the creatures still managed to reanimate after thawing, the team looked for physical qualities that might explain this superior resilience. It found that the Alaskan frogs stockpile astonishing amounts of a complex sugar called glycogen in their livers, which grow 1.5-fold relative to body mass as the amphibians prepare for winter. “This frog is like a walking liver,” says zoologist Jon Costanzo of Miami University in Oxford, Ohio, who led the research. The liver later converts this glycogen to glucose, a known cryoprotectant that quickly gets distributed to all the cells in the body when temperatures drop. The Alaskan frogs also accumulated about three times as much of the cryoprotectant urea in their blood plasma compared with frogs collected in Ohio, the team reports online today in The Journal of Experimental Biology. A third substance, whose identity is still mysterious, was present in Alaskan frogs, but not Ohioan ones. Costanzo and his team are on the case.