Biologists Study Alaska Bugs' "Antifreeze"

May 8, 2003

In interior Alaska, the winter temperatures average slightly below 0°F (-18°C). Frequently they dip to 20° below zero F (-29°C), and can dive to 60° below zero F (-51°C). Yet insects not only survive but thrive there. How?

In Anchorage, Todd Sformo, a graduate student in biology and environmental physiology at the University of Alaska-Fairbanks, retrieves one answer after another as he digs through a thin layer of spring snow to layers of dead leaves below.

There he unearths dozens of small green stink bugs—shield-shaped, half-inch-long creatures. Under a warming blanket of leaf litter, they have waited out winter in a state of reduced metabolism, or diapause, as researchers call it.

A secret of the insects' overwintering strategy lies in the blood, known as hemolymph.

Last month Sformo and other researchers came to Alaska to harvest that blood and purify the protein within it that allows the insect to "supercool" by lowering its freezing temperature.

The protein operates by a process known as thermal hysteresis, first identified in Antarctic fish—lowering the freezing point of water in the hemolymph. Insects, however, may practice hysteresis even more effectively.

To get enough of the protein, the researchers will have to collect thousands of the bugs at a rate of 1 microliter (it would take 250,000 microliters to gather a cup) of hemolymph per insect.

"I wish they were bigger," says Jack Duman, a biologist at Notre Dame University, in South Bend, Ind. "It would be nice if there were a two-pound stink bug."

Creamier Ice Creams, Hardier Plants

Duman and Brian Barnes, a University of Alaska-Fairbanks animal physiologist and head of the Institute for Arctic Biology, are co-leaders of the study supported by the National Science Foundation.

Duman first studied a similar protein in fish with Art DeVries, a biologist from Stanford University in Palo Alto, Calif., and a pioneer in researching "antifreeze protein," or AFP.

DeVries had wondered how Antarctic fish stay alive in waters cold enough to freeze them. In 1967, he found a gene capable of inhibiting the formation of ice crystals in water.

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