9317629 DeVries McMurdo Sound fishes are the most freeze resistant, and are exposed to greatest extremes of ice and temperature of any fishes in Antarctica. The project will focus on the extent of the ice association and its fate within these polar fishes. The deepest depths of ice exposure will also be determined. These results will be compared to those obtained for fishes living in less icy, warmer environments near the Antarctic Peninsula where the influence of ice shelves is absent. The fate of experimentally introduced endogenous ice will be determine to find out whether Antarctic fish possess mechanisms for disposing of accumulated ice. The relationship of structure to function of the antifreezes will also be investigated by determining the three- dimensional structures of some of the antifreeze peptides (AFPs) and searching for lattice matches between their polar residues and their ice adsorption plane. Two-Dimensional Nuclear Magnetic Resonance and molecular modeling techniques will be used. With the antifreeze glycopeptides (AFGPs), the importance of size for adsorption to specific planes will be determined. These studies will indicate what the important features are which give rise to antifreeze function in structurally diverse molecules. The investigation of the inhibition of ice growth by the various antifreezes (AFs) will also be continued on how adsorption to various ice planes leads to inhibition of ice growth. This question remains thus far unanswered, which they hope to address by examining the effects of the various AFs on the growth forms of single ice crystals. The organization and structure of the antifreeze genes of Antarctic fish will also be investigated by identifying and sequencing genes that code for the high molecular weight AFGPs and comparing them to organization of the small AFGPs. The sizes of the AFGP polyprotein gene family will be determined by fluorescent in situ hybridization. Information on the organization and struc ture will lead to an understanding of the factors that lead to the necessarily high levels of AF needed for survival in this extreme freezing Antarctic environment. ***
