Newton James R, Zenger Kyall R, Jerry Dean R
Aquaculture Genetics Research Program, School of Marine and Tropical Biology and Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Queensland 4811, Australia.
Mar Genomics. 2013 Sep;11:45-52. doi: 10.1016/j.margen.2013.07.002. Epub 2013 Aug 13.
Identification of genetically-regulated adaptation in fish is a precursor to understanding how populations will respond to future climate induced stressors like temperature. Australian populations of barramundi (Lates calcarifer) show strong evidence of local adaptation to temperature. However, the phenotypic consequences of this adaptation are unknown and the genetic mechanisms underlying this response are poorly understood. In the current study, two populations of barramundi from temperature extremes of the species Australian distribution were communally reared at cool (22°C), control (28°C) and hot (36°C) water temperatures for 3.5months. Southern populations of barramundi originating from a cooler environment grew significantly faster at 22°C than northern populations of warm adapted barramundi. However, no difference in population growth was present at either 28°C or 36°C. The underlying transcriptome profile of barramundi was examined via Illumina mRNA deep sequencing to determine the major contributing gene categories giving rise to phenotypic differences in barramundi population growth. Gene ontology (GO) analysis revealed enrichment in categories relating to the regulation of peptidase activity as well as microtubule, cytoplasmic and cellular metabolic based processes. Further analysis of the GO category "microtubule based process" with associated genes from the "response to stress" category revealed an apparent re-organization of cytoskeletal elements in response to an induced cold stress in northern barramundi reared at 22°C, when compared with northern barramundi reared at 36°C. Between southern barramundi and northern barramundi reared at 36°C, an analysis of the "endopeptidase inhibitor activity" GO category in conjunction with stress genes indicated a suppression of the complement system in southern barramundi along with an increase in the cellular stress response. The results of the present study show that southern populations of barramundi exhibit underlying molecular adaptation to cooler water temperatures, but still retain a tolerance for warm water temperatures. Furthermore, GO profiling has revealed groups of genes that underlie population differences in temperature tolerance as a means to prioritize the analysis of differential gene expression in studies of local adaptation in the future.
识别鱼类中基因调控的适应性是理解种群将如何应对未来温度等气候诱导应激源的前提。澳大利亚的尖吻鲈（Lates calcarifer）种群显示出对温度进行局部适应的有力证据。然而，这种适应的表型后果尚不清楚，对这种反应背后的遗传机制也知之甚少。在当前研究中，将来自该物种澳大利亚分布温度极端区域的两个尖吻鲈种群在凉爽（22°C）、对照（28°C）和炎热（36°C）水温下共同饲养3.5个月。来自较凉爽环境的南方尖吻鲈种群在22°C时的生长速度明显快于适应温暖环境的北方尖吻鲈种群。然而，在28°C或36°C时，种群生长没有差异。通过Illumina mRNA深度测序检查尖吻鲈的潜在转录组图谱，以确定导致尖吻鲈种群生长表型差异的主要基因类别。基因本体（GO）分析显示，与肽酶活性调控以及基于微管、细胞质和细胞代谢的过程相关的类别中存在富集。对“基于微管的过程”GO类别与来自“应激反应”类别的相关基因进行进一步分析发现，与在36°C饲养的北方尖吻鲈相比，在22°C饲养的北方尖吻鲈在受到诱导冷应激时，细胞骨架成分出现明显重组。在36°C饲养的南方尖吻鲈和北方尖吻鲈之间，结合应激基因对“内肽酶抑制剂活性”GO类别进行分析表明，南方尖吻鲈的补体系统受到抑制，同时细胞应激反应增加。本研究结果表明，南方尖吻鲈种群对较凉爽水温表现出潜在分子适应，但仍保留对温暖水温的耐受性。此外，GO分析揭示了构成温度耐受性种群差异基础的基因群，作为未来在局部适应研究中优先分析差异基因表达的一种手段。
