Assembly and Stability of Microtubules from Antarctic Fish at Low Temperatures

这项研究的长期目标是在分子水平上确定使南极鱼类的微管能够在这些适应寒冷的脊椎动物所经历的低体温（-2至+2摄氏度）下聚合的结构适应性，并检查鱼类微管的动力学。该项目的具体目标有五个：1)比较南极和温带南极鱼类脑小管的组装能量；2)克隆和测序南极和温带南极鱼脑小管编码的dna（与信使rna互补的dna）；3)确定南极鱼类的微管蛋白基因结构，也可能是温带南极鱼的微管蛋白基因；4)确定导致南极鱼类脑和卵小管功能差异的结构特征；5)研究南极鱼类微管在低温下的动态行为。分子生物学实验将对从南极鳕鱼（Notothenia coriiceps忽视）及其温带同系物新西兰黑鳕鱼（N. angustata）的核酸中提取的微管蛋白cdna和基因进行。此外，南极鱼类微管在低温下的动态将通过视频增强光显微方法进行检查。将南极鱼类的微管蛋白与相关温带鱼类和温血脊椎动物的微管蛋白的初级序列和翻译后修饰进行比较，可以揭示低温下微管组装所需的分子相互作用和结构特征。这项工作将为南极极端变温动物的微管蛋白基因结构提供有价值的信息。

The long-range goals of the proposed research are to determine, at the molecular level, the structural adaptations that enable the tubulins of Antarctic fishes to polymerize at the low body temperatures (-2 to +2 C) experienced by these cold-adapted vertebrates, and to examine the dynamics of the fish microtubules. The specific objectives of this project are five in number: 1) to compare the assembly energetics of brain tubulins from Antarctic and temperate nototheniid fishes; 2) to clone and to sequence cDNAs (DNAs complementary to messenger RNAs) that encode the brain tubulins of Antarctic and temperate nototheniid fishes; 3) to determine the structures of tubulin genes from an Antarctic fish, and possibly from a temperate nototheniid; 4) to determine the structural features responsible for the functional differences between brain and egg tubulins of an Antarctic fish; and 5) to characterize the dynamic behaviors of Antarctic fish microtubules at low temperatures. Molecular- biological experiments will be performed on tubulin cDNAs and genes derived from the nucleic acids of the Antarctic cod, Notothenia coriiceps neglecta, and of its temperate congener, the New Zealand black cod, N. angustata. Additionally, the dynamics of Antarctic fish microtubules at low temperatures will be examined by video-enhanced light-microscopic methods. Comparison of the primary sequences and posttranslational modifications of tubulins from Antarctic fishes with those of tubulins from related temperate fishes and warm-blooded vertebrates should reveal the molecular interactions and structural features necessary for microtubule assembly at low temperatures. This work will provide valuable information concerning the structure of tubulin genes from an extreme Antarctic poikilotherm.