Comprehensive Analyses of Antifreeze Capacities in Arctic and Northern Cods at the Protein and Encoded Levels, and the Molecular of the Cod Antifreeze Glycoprotein Gene

北极和北方鳕鱼抗冻能力的蛋白质和编码水平以及鳕鱼抗冻糖蛋白基因分子的综合分析

• 批准号: 0002654
• 负责人: Chi-Hing Cheng
• 金额: $ 44.26万
• 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: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0002654&HistoricalAwards=false
• 关键词: Comprehensive; Analyses; Antifreeze; Capacities; Arctic

The twenty-four or so cod species of the Arctic and northern cool-temperate oceans belonging to the family Gadidae include many of the most commercially important cod fishes. Five of these species are known to have an antifreeze glycoprotein (AFGP) that is important for their survival in their various cold-water habitats. Most of the cod AFGP studies were conducted during 1975-1985, and provided basic information on the protein structure and seasonal changes in AFGP levels in some of the five known AFGP-bearing cods. None of the other cods that may encounter freezing conditions have been examined for possible presence of an antifreeze function, and no information at all on the cod AFGP function at the molecular level was available until 1997 when the first AFGP gene sequence and structure from the Arctic cod Boreogadus saida were reported with a high AFGP coding capacity in this most-northerly species. Thus the AFGP systems of the different cod species are far from being thoroughly understood. This project proposes to conduct comprehensive characterizations and analyses of the AFGP system of the different gadids using contemporary techniques. The overall goal is to assess their respective freeze-avoidance capacities at both the protein (AFGP protein structures and production) and molecular (AFGP genes and gene families and their transcription) levels, and how these relate to the differential physiological demands imposed by their diverse habitats which span a range of latitudes and environmental severity. The AFGP systems of the cods will be contrasted among the cod species, and with the constitutive high capacities in their south-polar counterparts, the Antarctic notothenioids, which are unrelated perciform fishes that make a near-identical AFGP to survive in the world's most thermally stable and coldest marine waters at the opposite pole. A key question in the field of antifreeze research is where these novel antifreeze proteins came from. The PIs have previously determined the evolutionary origin and molecular mechanism that produced the Antarctic notothenioid AFGP gene which played a crucial role in the survival and organismal success of these fishes in the frigid Antarctic waters. Through molecular analyses, the second major goal of the project is to decipher the origin and evolutionary history of the cod AFGP gene, that had led to the remarkable 'bipolar' evolutionary convergence of similar AFGPs in two unrelated fish groups.Ten different marine gadid species, one of which includes two genetically distinct populations, will be examined. Specific areas of studies include: (1) comparative analyses of blood AFGP levels, protein structure and heterogeneity between and within cod species from different latitudes and habitats to determine the influence of environmental severity on antifreeze production; (2) determination of the circannual AFGP production cycles (AFGP protein levels and transcription of mRNA) of three high-latitude cods and their relationship to the temporal variations in environmental conditions specific to each of their habitats; (3) determination of the encoded capacity for AFGP production in different cods by analyzing the complexity of their AFGP gene sequences, structures, the organization of these genes in the genome, and the size of the gene family; (4) characterization of the distribution of AFGP expression in different tissues and non-vascular fluid compartments to determine all possible lines of defense against freezing in the cods; (5) determination whether hitherto unexamined gadids (6 different northerly distributed species) have an antifreeze protein through detection for both blood antifreeze activity and presence of AFGP-like sequences in their genome; and (6) deciphering the origin and the evolutionary process of cod AFGP gene.

属于Gadidae家族的北极和北部凉爽的海洋的二十四种鳕鱼都包括许多最重要的鳕鱼鱼。众所周知，这些物种中有五种具有抗冻糖蛋白（AFGP），这对于它们在各种冷水栖息地中的生存至关重要。大多数COD AFGP研究都是在1975 - 1985年期间进行的，并提供了有关五个已知的AFGP含COD中一些AFGP水平的蛋白质结构和季节变化的基本信息。还没有检查任何可能遇到冻结条件的COD来存在抗冻功能，并且直到1997年，北极CoD Cod Boreogadus Saida的第一个AFGP基因序列和结构都没有据报道，在这一大多数人的AFGP编码能力上，直到1997年才能获得有关COD AFGP功能的信息。因此，不同鳕鱼物种的AFGP系统远未被彻底理解。该项目建议使用当代技术对不同GADID的AFGP系统进行全面的特征和分析。总体目标是评估其在蛋白质（AFGP蛋白质结构和生产）以及分子（AFGP基因和基因家族及其转录）水平的冻结避免能力，以及这些水平如何与散布范围和环境严重程度范围的多种习惯所施加的差异生理需求相关。鳕鱼的AFGP系统将在鳕鱼物种之间形成鲜明对比，与南极对应物中的本构型高能力，南极的非刺毒素是无关的percoriform鱼类，它们是几乎相同的AFGP，它们是世界上最稳定和最冷的海洋水域中生存的几乎相同的AFGP。在抗冻研究领域的一个关键问题是这些新型的抗冻蛋白的来源。 PI先前已经确定了产生南极非噻壳霉素AFGP基因的进化起源和分子机制，该基因在这些鱼类在冰冷的南极水中的生存和生物成功中起着至关重要的作用。通过分子分析，该项目的第二个主要目标是破译COD AFGP基因的起源和进化史，这导致了两个无关鱼类中相似的AFGP的显着“双极”的进化收敛。TENTEN不同的海洋gadid物种，其中之一包括两个基因差异众多的群体，将被检查。研究的特定领域包括：（1）对血液AFGP水平，蛋白质结构和异质性的比较分析，来自不同纬度和栖息地的鳕鱼物种之间的异质性，以确定环境严重程度对抗冻冻产生的影响； （2）确定三种高纬度鳕鱼的准入AFGP生产周期（AFGP蛋白水平和mRNA的转录）及其与其每个栖息地特有的环境条件下的时间变化的关系； （3）通过分析其AFGP基因序列，结构，基因组中这些基因的组织的复杂性以及基因家族的大小来确定不同COD中AFGP产生的编码能力； （4）表征不同组织和非血管液室中AFGP表达的分布，以确定所有可能的防御线，以防止COD中的冷冻； （5）确定迄今未经检查的gadids（6种不同的北分布物种）是否通过检测血液抗冻活性和基因组中AFGP样序列的存在而具有抗冻蛋白； （6）鳕鱼AFGP基因的起源和进化过程。