The Role of Antifreeze Proteins in Freezing Avoidance of Antarctic Fishes

9317629 DeVries麦克默多健全的鱼是最抗冻，并暴露在最极端的冰和温度的任何鱼类在南极洲。该项目将侧重于冰协会的范围及其在这些极地鱼类中的命运。 还将确定冰暴露的最深深度。 这些结果将与南极半岛附近不存在冰架影响的冰少、温暖环境中的鱼类所获得的结果进行比较。 实验引入的内源性冰的命运将被确定，以查明南极鱼类是否具有处理积累的冰的机制。 还将通过确定某些抗冻肽（AFP）的三维结构并寻找其极性残基与其冰吸附平面之间的晶格匹配来研究抗冻剂的结构与功能的关系。 将使用二维核磁共振和分子建模技术。 对于抗冻糖肽（AFGPs），将确定吸附到特定平面的大小的重要性。这些研究将表明，在结构不同的分子中，引起抗冻功能的重要特征是什么。还将继续研究各种防冻剂（AF）对冰生长的抑制作用，研究吸附到各种冰平面上如何导致冰生长的抑制。到目前为止，这个问题仍然没有答案，他们希望通过检查各种AF对单个冰晶生长形式的影响来解决这个问题。 南极鱼类抗冻基因的组织和结构也将通过鉴定和测序编码高分子量AFGPs的基因并将其与小AFGPs的组织进行比较来研究。 AFGP多蛋白基因家族的大小将通过荧光原位杂交来确定。 关于组织和结构的信息将导致对导致在这种极端寒冷的南极环境中生存所需的必然高水平AF的因素的理解。 ***

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. ***