Beijing Key Laboratory of Fishery Biotechnology, Beijing Fisheries Research Institute, Beijing, 100068, China.
BMC Genomics. 2020 Oct 23;21(1):737. doi: 10.1186/s12864-020-07139-z.
Tropical stenothermal fish exhibit special tolerance and response to cold stress. However current knowledge of the molecular mechanisms response to cold stress in aquatic ectotherms is largely drawn from eurythermal or extreme stenothermal species. The tiger barb Puntius tetrazona is a tropical stenothermal fish, with great popularity in aquarium trade and research.
To investigate the response mechanism of P. tetrazona to low temperature, fish were exposed to increasing levels of acute cold stress. Histopathological analysis showed that the brain, gill, liver and muscle tissues appeared serious damage after cold stress (13 °C). Brain, gill, liver and muscle tissues from control (CTRL) groups (27 °C) and COLD stress groups (13 °C) of eight-month fish (gender-neutral) were sampled and assessed for transcriptomic profiling by high-throughput sequencing. 83.0 Gb of raw data were generated, filtered and assembled for de novo transcriptome assembly. According to the transcriptome reference, we obtained 392,878 transcripts and 238,878 unigenes, of which 89.29% of the latter were annotated. There were 23,743 differently expressed genes (DEGs) been filtered from four pairs of tissues (brain, gill, liver and muscle) between these cold stress and control groups. These DEGs were mainly involved in circadian entrainment, circadian rhythm, biosynthesis of steroid and fatty acid. There were 64 shared DEGs between the four pairs of groups, and five were related to ubiquitylation/deubiquitylation. Our results suggested that ubiquitin-mediated protein degradation might be necessary for tropical stenothermal fish coping with acute cold stress. Also, the significant cold-induced expression of heat shock 70 kDa protein (HSP70) and cold-induced RNA-binding protein (CIRBP) was verified. These results suggested that the expression of the molecular chaperones HSP70 and CIRBP in P. tetrazona might play a critical role in coping with acute cold stress.
This is the first transcriptome analysis of P. tetrazona using RNA-Seq technology. Novel findings about tropical stenothermal fish under cold stress (such as HSP70 and CIRBP genes) are presented here. This study contributes new insights into the molecular mechanisms of tropical stenothermal species response to acute cold stress.
热带狭温鱼类对冷应激表现出特殊的耐受和反应。然而，水生变温动物对冷应激的分子机制的现有知识主要来自于广温或极端狭温物种。虎皮鱼 Puntius tetrazona 是一种热带狭温鱼类，在水族馆贸易和研究中非常受欢迎。
为了研究 P. tetrazona 对低温的反应机制，将鱼暴露于逐渐增加的急性冷应激水平下。组织病理学分析显示，在冷应激（13°C）后，大脑、鳃、肝和肌肉组织出现严重损伤。从 8 个月大的（性别中性）鱼的对照组（27°C）和冷应激组（13°C）的大脑、鳃、肝和肌肉组织中取样，并通过高通量测序进行转录组谱分析。生成了 83.0 Gb 的原始数据，经过过滤和组装用于从头转录组组装。根据转录组参考，我们获得了 392878 个转录本和 238878 个 unigenes，其中后者的 89.29%被注释。从冷应激和对照组的四对组织（大脑、鳃、肝和肌肉）之间的 4 对组织中筛选出 23743 个差异表达基因（DEGs）。这些 DEGs 主要参与昼夜节律、昼夜节律、类固醇和脂肪酸的生物合成。在四对组织中，有 64 个共同的 DEGs，其中 5 个与泛素化/去泛素化有关。我们的结果表明，泛素介导的蛋白质降解可能是热带狭温鱼类应对急性冷应激所必需的。此外，还验证了热休克 70kDa 蛋白（HSP70）和冷诱导 RNA 结合蛋白（CIRBP）的显著冷诱导表达。这些结果表明，P. tetrazona 中分子伴侣 HSP70 和 CIRBP 的表达可能在应对急性冷应激中发挥关键作用。
这是首次使用 RNA-Seq 技术对 P. tetrazona 进行的转录组分析。本文介绍了热带狭温鱼类在冷应激下的新发现（如 HSP70 和 CIRBP 基因）。这项研究为热带狭温物种对急性冷应激的分子机制提供了新的见解。
