2002-2003 Science Planning Summary

Biology & Medicine

Dr. Polly Penhale
Program Manager


NSF/OPP 00-87971
Station: McMurdo Station
RPSC POC: Steve Alexander
Research Site(s): Sea Ice, McMurdo Sound, Cape Evans, New Harbor, Ross Ice Shelf, Wohlschlag Bay

Evolutionary loss of the heat shock response in antarctic fishes
Dr. Gretchen E. Hofmann
Arizona State University Tempe
Department of Biology

Deploying Team Members: Timothy Crombie . Bev Dickson . Gretchen E Hofmann . Sean P Place . Allsion C Whitmer . Mackenzie L Zippay
Research Objectives: Evolution has crafted a way for organisms to respond to the stress of abrupt environmental changes, in particular a sudden elevation of temperature. Commonly viewed as a "universal" characteristic of organisms, the heat-shock response (HSR) triggers previously inactive genes to synthesize one or more classes of molecular chaperones, known as heat-shock proteins (Hsps). But what about Antarctica, where such a sudden burst of heat is so unlikely? In previous studies on a cold-adapted, stenothermal antarctic teleost fish, Trematomus bernacchii, it was determined that this adaptational response has been lost over evolutionary time.

If evolution at subzero temperatures has indeed altered the gene expression patterns for molecular chaperones in antarctic fish, then the study of how cells respond to temperature at a molecular level may be a legitimate, new frontier in biology . At this stage, however, though HSR - perhaps the quintessential example of the environmental regulation of gene expression - has been well-described at the cellular level, there is little information on how the response is actually regulated in ectothermic animals in a natural environment.

This project's goal is to build upon that evolutionarily significant observation by examining this profound change in the environmental regulation of gene expression on two levels. First, researchers will try to establish how widespread the loss of the HSR might be in the suborder Notothenoidei, including antarctic and non-antarctic members of the group. Second, they will try to determine the nature of the lesion in gene expression that accounts for the loss of the expression of stress-inducible genes in antarctic species. Both of these objectives will entail experiments on closely related, cold temperate species from New Zealand waters.

Ultimately, the lesions in the Hsp gene expression in antarctic notothenioids may serve to highlight aspects of the "cellular thermostat" and to provide key information about the actual molecular response mechanism triggered by environmental stress. The results should contribute to our knowledge of the environmental physiology and evolutionary biology of the antarctic notothenioid fishes, as well as enhance our understanding of the extreme stenothermality in these fish.

Field Season Overview:
Support contractor personnel will drill fishing holes through the sea ice near McMurdo Station. Project team members will travel by snowmobile, tracked vehicle and helicopter to these fishing holes to collect fish using line and bottom traps. Specimens will be transported to the Crary Lab aquarium for biochemical and genetic analyses. Some samples will be returned to the researcher's home institution for further analysis.