Environmental, Organismal and Evolutionary Physiology of Freeze Avoidance in Antarctic Notothenioid Fishes

南极诺托尼类鱼类的环境、有机和进化生理学避免冰冻

• 批准号: 0636696
• 负责人: Arthur DeVries
• 金额: $ 52.53万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0636696&HistoricalAwards=false
• 关键词: Environmental; Organismal; Evolutionary; Physiology; Freeze

Antarctic notothenioid fish evolved antifreeze (AF) proteins that prevent ice crystals that enter their body fluids from growing, and thereby avoid freezing in their icy habitats. However, even in the extreme cold Antarctic marine environment, regional gradations of severity are found. The biological correlate for environmental severity in fish is the endogenous ice load, which likely determines the tolerable limit of environmental severity for notothenioid habitation. The endogenous ice load develops from environmental ice crystals entering through body surfaces and somehow localizing to the spleen. How prone the surface tissues are to ice entry, how ice reaches the spleen, and what the fate of splenic ice is, requires elucidation. Spleen sequestration of ice raises the hypothesis that macrophages may play a role in the translocation and perhaps elimination of AF-bound ice crystals. Antifreeze glycoproteins (AFGP) act in concert with a second, recently discovered antifreeze called antifreeze potentiating protein (AFPP), necessitating an assessment of the contribution of AFPP to freezing avoidance. Recent research suggests that the exocrine pancreas and the anterior stomach, not the liver, synthesize AFGPs and secrete them into the intestine, from where they may be returned to the blood. A GI-to-blood transport is a highly unconventional path for a major plasma protein and also begs the questions, What is the source of blood AFPP?. Why are two distinct AF proteins needed and what is the chronology of their evolution? What genomic changes in the DNA are associated with the development or loss of the antifreeze trait? Experiments described in this proposal address these interrelated questions of environmental, organismal, and evolutionary physiology, and will further our understanding of novel vertebrate physiologies, the limits of environmental adaptation, and climatically driven changes in the genome. The proposed research will (1) determine the temporal and spatial heterogeneity of environmental temperature and iciness in progressively more severe fish habitats in the greater McMurdo Sound area, and in the milder Arthur Harbor at Palmer Station. The splenic ice load in fishes inhabiting these sites will be determined to correlate to environmental severity and habitability. (2) Assess the surface tissue site of ice entry and their relative barrier properties in intact fish and isolated tissues preparations (3) Assess the role of immune cells in the fate of endogenous ice, (4) determine whether the blood AFGPs are from intestinal/rectal uptake, (5) examine the contribution of AFPP to the total blood AF activity (6) evaluate the progression of genomic changes in the AFGP locus across Notothenioidei as modulated by disparate thermal environments, in four selected species through the analyses of large insert DNA BAC clones. The origin and evolution of AFPP will be examined also by analyzing BAC clones encompassing the AFPP genomic locus. The broader impacts of the proposed research include training of graduate and undergraduate students in research approaches ranging from physical field measurements to cutting edge genomics. Undergraduate research projects have lead to co-authored publications and will continue to do so. Outreach includes establishing Wiki websites on topics of Antarctic fish biology and freeze avoidance, providing advisory services to the San Francisco Science Exploratorium, and making BAC libraries available to interested polar biologists. This research theme has repeatedly received national and international science news coverage and will continue to be disseminated to the public in that manner.

南极南极鱼进化出抗冻蛋白（AF），可以防止进入它们体液的冰晶生长，从而避免在冰冷的栖息地冻结。然而，即使在极端寒冷的南极海洋环境中，区域的严重程度gradations. The生物学相关的环境的严重性在鱼类是内源性的冰负荷，这可能决定了可容忍的限制环境的严重性notothenioid栖息地。内源性冰负荷是由环境冰晶通过体表进入并以某种方式定位于脾脏而产生的。表面组织有多容易被冰进入，冰是如何到达脾脏的，脾脏冰的命运是什么，需要阐明。脾脏的冰隔离提出了这样的假设，即巨噬细胞可能在转移和消除AF结合的冰晶中发挥作用。抗冻糖蛋白（AFGP）与最近发现的第二种抗冻剂抗冻增强蛋白（AFPP）协同作用，因此有必要评估AFPP对避免冻结的贡献。最近的研究表明，外分泌胰腺和前胃，而不是肝脏，合成AFGP并将其分泌到肠中，从那里它们可以返回血液。GI向血液的转运是一种主要血浆蛋白的高度非常规途径，也引出了一个问题：血液AFPP的来源是什么？为什么需要两种不同的AF蛋白，它们的进化时间是什么？DNA中的哪些基因组变化与抗冻特性的发展或丧失有关？ 本提案中描述的实验解决了环境，有机体和进化生理学的这些相互关联的问题，并将进一步加深我们对新的脊椎动物生理学，环境适应的限制以及气候驱动的基因组变化的理解。 拟议的研究将（1）确定环境温度和冰冷的时间和空间异质性，逐步更严重的鱼类栖息地在大麦克默多声音地区，并在温和的亚瑟港在帕尔默站。 脾冰负荷鱼类栖息在这些网站将被确定为相关的环境的严重性和可居住性。(2)评估冰进入的表面组织部位及其在完整鱼和分离的组织制备物中的相对屏障性质（3）评估免疫细胞在内源性冰的命运中的作用，（4）确定血液AFGP是否来自肠/直肠摄取，（5）检查AFPP对总血液AF活性的贡献（6）通过对大插入DNA BAC克隆的分析，在四个选定的物种中评估由不同的热环境调节的Notothenioidei中AFGP基因座的基因组变化的进展。AFPP的起源和进化也将通过分析包含AFPP基因组位点的BAC克隆来检查。 拟议的研究的更广泛的影响包括研究生和本科生的研究方法，从物理场测量到尖端基因组学的培训。本科生的研究项目导致共同撰写的出版物，并将继续这样做。外联活动包括建立关于南极鱼类生物学和防冻专题的维基网站，向旧金山弗朗西斯科科学探索馆提供咨询服务，并向感兴趣的极地生物学家提供生物咨询中心图书馆。这一研究主题多次得到国家和国际科学新闻的报道，并将继续以这种方式向公众传播。