Temperature adaptation of fish - molecular mechanisms involved and application

鲤鱼适应环境温度，诱导编码肌球蛋白重链亚型的基因主要在驯化10和30℃的鱼类中表达。温度驯化后鲤鱼的这种生化变化也可以通过肌浆网和各种酶等细胞内器官观察到。似乎，鱼会动态地改变许多细胞成分，以应对环境温度。人们认为，环境温度信号被传递到中枢神经系统，随后通过各种激素调节作用于基因表达。本研究的目的是为了揭示鱼类温度适应的分子机制，并将所获得的结果用于工业应用。克隆了10个℃和30个℃类型的鲤肌球蛋白重链亚型的5‘上游调控区，并对其结构完整性进行了测定，从而鉴定了MeF_2结合元件RES…更重要的是基因表达的激活。此外，研究还发现，青鱼肌球蛋白重链基因的5‘-上游区域也参与了对温度相关基因表达的调控。鲤鱼对低温的适应增加了55 kDa胞浆蛋白的表达水平。该蛋白是线粒体FOF1-ATPase的一个亚基，在温度从30℃升高到10℃时，其含量增加了两倍。这种不同的表达依赖于驯化温度在转录水平上进行调控。全年定期从鹿儿湖采集各种鱼类，并测定快速骨骼肌肌原纤维的ATPase活性。11月份采集的FISH活性最高，6、7月份活性最低。建立了利用压敏探针和荧光成像技术测定线粒体膜电压的分析方法。用这种方法成功地测量了鱼类适应环境温度后线粒体膜电压相关势能的变化。较少

Carp acclimates to environmental temperature and induces genes encoding myosin heavy chain isoforms predominantly expressed for fish acclimated to 10 and 30 ℃. Such changes in biochemical changes in carp following temperature acclimation are also observed with intracellular apparatus such as sarcoplasmic reticulum and various enzymes. It seems that, fish alters dynamically many cellular components in response to environmental temperatures. It is considered that environmental temperature signals are transmitted to the central nervous system and subsequently act on gene expression via various hormonal regulations. The objective of this study was to disclose molecular mechanisms involved in temperature adaptation of fish and to utilize the results obtained for industrial application.The 5' upstream regulatory regions of the 10 ℃- and 30 ℃-type carp myosin heavy chain isoforms were cloned and determined for their structural integrity, resulting in identification of MEF2 binding element res … More ponsible for activation of gene expression. Furthermore, it was found that 5'-upstream regions of myosin heavy chain genes from medaka, another eurythermal fish, also participate in such regulation for temperature-dependent gene expression.Carp increased expression levels of 55 kDa cytosolic protein in association with acclimation to cold temperature. This protein was found to be one of subunits of mitochondrial FOF1-ATPase and increased its quantities two times following temperature shift from 30 ℃ to 10 ℃. Such different expression depending on acclimation temperature was regulated at the transcription level.Various fish species were collected from Kasumigaura Lake periodically all around the year and determined for ATPase activity of fast skeletal muscle myofibrils. The activity was the highest with fish collected in November and decreased gradually reaching the minimum value in June and July.Analytical method to determine mitochondrial membrane voltage was developed by using voltage-sensitive probe and fluorescence imaging. Changes in voltage-associated potential energy of mitochondrial membranes following adaptation to environmental temperatures of fish were successfully measured by this method. Less