COLUMBUS , Ohio -- The larvae of Antarctic midges never stop producing special proteins that minimize environmental stress, allowing them to withstand a range of intense environmental conditions in one of the world's harshest environments.
Scientists found that adult midges (Belgica antarctica) lose their ability to continually express these protective heat-shock proteins. Instead, like most animals, adult midges produce these proteins only when they are stressed. The discovery currently appears in the online edition of the Proceedings of the National Academy of Sciences.
The proteins help defend the larval midges against environmental stresses including temperature changes as well as changes in water, oxygen and pH levels, said David Denlinger, the study's lead author and a professor of entomology at Ohio State University.
"They've somehow figured out a way to maintain a level of these heat-shock, or stress, proteins and still make proteins that are vital for growth and development," he said.
This mechanism seems to offer the larvae protection during their two-year life span, most of which is spent encased in ice.
All animals, including humans, make heat shock proteins, but normally they only do so during times of extreme physical stress. Curiously, adult midges don't express these proteins all the time only during periods of extreme environmental stress. Yet when most insects express stress proteins, it temporarily compromises the production of other proteins, Denlinger said.
"The production of stress proteins usually brings development to a halt," he said. "But in this case, the larvae merrily go about their business of feeding and growing while producing their stress proteins."
The Antarctic midge is barely bigger than a grain of rice, but it's still the largest free-roaming terrestrial animal to inhabit Antarctica. The larvae resemble tiny black worms.