Antarctic Notothenioid Fish Freeze Avoidance and Genome-wide Evolution for Life in the Cold

南极诺氏类鱼类表现出两种适应寒冷环境的特征。第一个是在他们的血液和组织中产生抗冻蛋白。第二个是在极端寒冷的温度下系统范围内执行细胞和生理功能的能力。提议的目标是展示南极鱼类如何利用这些特征来避免冰冻，以及哪些额外的基因被开启或被抑制，以便这些鱼类在极端寒冷的温度下保持正常的生理功能。在高纬度麦克默多海湾和罗斯陆架地区，栖息地逐渐变冷，而在南极半岛西部，近岸水域环境变得温和一些。通过量化冰晶入侵和滞留在脾中的程度，麦克默多声音鱼在南半球夏季(10月至2月)的百分比将与南半球冬季(7月至9月)的WAP潮间带鱼类进行比较，以证明它们避免冻结的能力和程度。表面上皮(如皮肤、鳃和肠壁)对冰进入的抵抗力是这些鱼适应其他致命冰冻条件的另一种表现。通过对转录组(构成整个基因组表达的一组蛋白质的前体的一组表达的RNA转录本)的研究，将探索独特的极地基因组的适应性质。将对三个诺氏类物种(E.maclovinus、D.mawsoni和C.aceratus)进行分析，以记录在极端长期寒冷下由生命塑造的进化遗传变化(包括获得和损失)。将在这些不同物种上进行差异基因表达(DGE)研究，以评估组织范围内对热挑战反应的进化修饰。转录本和其他测序文库将有助于从新开始的冰鱼基因组测序工作。

Antarctic notothenioid fishes exhibit two adaptive traits to survive in frigid temperatures. The first of these is the production of anti-freeze proteins in their blood and tissues. The second is a system-wide ability to perform cellular and physiological functions at extremely cold temperatures.The proposal goals are to show how Antarctic fishes use these characteristics to avoid freezing, and which additional genes are turned on, or suppressed in order for these fishes to maintain normal physiological function in extreme cold temperatures. Progressively colder habitats are encountered in the high latitude McMurdo Sound and Ross Shelf region, along with somewhat milder near?shore water environments in the Western Antarctic Peninsula (WAP). By quantifying the extent of ice crystals invading and lodging in the spleen, the percentage of McMurdo Sound fish during austral summer (Oct-Feb) will be compared to the WAP intertidal fish during austral winter (Jul-Sep) to demonstrate their capability and extent of freeze avoidance. Resistance to ice entry in surface epithelia (e.g. skin, gill and intestinal lining) is another expression of the adaptation of these fish to otherwise lethally freezing conditions.The adaptive nature of a uniquely characteristic polar genome will be explored by the study of the transcriptome (the set of expressed RNA transcripts that constitutes the precursor to set of proteins expressed by an entire genome). Three notothenioid species (E.maclovinus, D. Mawsoni and C. aceratus) will be analysed to document evolutionary genetic changes (both gain and loss) shaped by life under extreme chronic cold. A differential gene expression (DGE) study will be carried out on these different species to evaluate evolutionary modification of tissue-wide response to heat challenges. The transcriptomes and other sequencing libraries will contribute to de novo ice-fish genome sequencing efforts.