Rainbow smelt, Osmerus mordax, have an impressive ability to acclimate to very cold water. Rainbow smelt exposed to cold (<5 °C) for an extended period of time have faster sustained swimming speeds and increased contraction kinetics in their myotomal muscle compared to warm acclimated fish. We used RNA Sequencing reactions (RNA-Seq) to explore how gene expression underlies thermal acclimation by muscle in these fish. Transcriptome analysis is limited in species that lack an annotated genome, such as rainbow smelt. The Trinity software package permits the de novo assembly of a rainbow smelt transcriptome with a modest learning curve. The transcriptome was then analyzed with Kallisto to quantify the abundance of each transcript represented in the full transcriptome and Sleuth to analyze the resulting RNA-seq datasets. Subsequently qPCR was used to explore patterns of thermal acclimation and gene expression for genes of metabolic and muscle contractile function. These methodologies revealed shifts in both muscle and metabolic gene expression that contribute to the thermal acclimation response in rainbow smelt. In fast-twitch, anaerobic white muscle, slow isoforms of myosin heavy and light chain tended to be down-regulated with exposure to cold in myotomal muscle, while fast isoforms were unchanged. Genes associated with protein turnover and aerobic metabolism were up-regulated in the white muscle, while those associated with anaerobic metabolism and the cell cycle were down-regulated. Collectively the results suggest that thermal acclimation to cold is complex process of apparent shifts in gene expression.

彩虹的气味，Osmerus mordax，具有非常强的适应非常冷水的能力。与温热适应的鱼类相比，长时间暴露在寒冷（<5°C）下的彩虹熔炼者具有更快的持续游泳速度，并增强了其肌肌的收缩动力学。我们使用RNA测序反应（RNA-Seq）来探索基因表达如何成为这些鱼类肌肉热适应的基础。转录组分析仅限于缺少注释基因组的物种，例如彩虹熔炼。在三位一体软件包允许从头组装一个彩虹胡瓜转录组具有适中的学习曲线。然后用Kallisto分析转录组量化完整转录组和Sleuth中每个转录本的丰度分析所得的RNA-seq数据集。随后，使用qPCR探索代谢和肌肉收缩功能基因的热适应和基因表达模式。这些方法揭示了肌肉和代谢基因表达的变化，这些变化有助于彩虹熔炼中的热驯化反应。在快速抽搐的无氧性白肌中，肌球蛋白重链和轻链的慢型同工型在肌肉肌中暴露于寒冷时趋于下调，而快速同型型则没有变化。与蛋白质更新和有氧代谢有关的基因在白肌肉中被上调，而与无氧代谢和细胞周期有关的基因被下调。总的来说，结果表明热适应寒冷是基因表达明显变化的复杂过程。