The intertidal mussel Mytilus californianus is subjected to thermal and oxygen cycles due to fluctuations of the tidal cycle. Mussels that reside in high-shore microenvironments experience extended periods of aerial-exposure and greater thermal challenges than low-shore populations. In this study, we investigated the combined effect of daily extended periods of aerial-exposure and midday thermal events on the physiology of mussels by monitoring transcriptome-wide gene expression in a simulated tidal environment. Mussels were acclimated to aerial-exposure for 20 h a day combined with a simulated midday solar heating event of + 8 °C. Results revealed that 11% of the transcriptome exhibited robust patterns of rhythmic gene expression. Two broad sets of genes were induced, including one that was upregulated during the daytime thermal stress period and another following the 4-h evening high-tide. The daytime thermal stress associated gene set was enriched for genes related to cellular regulatory pathways such as those that encode transcription factors while genes expressed following evening submergence varied in functional theme. Additionally, genes related to energy metabolism were also upregulated during warming periods of the tidal cycle. Comparing these data to published data from a previous tidal simulation study revealed that acclimation to daily heat stress yielded a muted transcriptional response to heat compared to an acute response observed in mussels maintained under isothermal conditions. These results indicate that M. californianus displays phenotypic plasticity with respect to transcriptomic expression and that this trait likely promotes homeostasis in the intertidal environment.

中文翻译：

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热量和空气暴露的循环诱导与加州贻贝细胞调节和代谢相关的转录组变化

由于潮汐循环的波动，潮间带贻贝 Mytilus californianus 受到热循环和氧循环的影响。生活在高岸微环境中的贻贝比低岸种群经历了更长的空中暴露时间和更大的热挑战。在这项研究中，我们通过在模拟潮汐环境中监测转录组范围内的基因表达，研究了每日长时间的空中暴露和正午热事件对贻贝生理的综合影响。贻贝适应了每天 20 公顷的空中暴露，并结合模拟的正午太阳加热事件 + 8 °C。结果显示，11% 的转录组表现出稳健的节律基因表达模式。诱导了两组广泛的基因，包括在白天热应激期间上调的一种，另一种在晚间高潮后 4 小时后上调。白天热应激相关基因集富含与细胞调节途径相关的基因，例如编码转录因子的基因，而在夜间淹没后表达的基因在功能主题上有所不同。此外，在潮汐周期变暖期间，与能量代谢相关的基因也被上调。将这些数据与先前潮汐模拟研究的已发表数据进行比较，表明与在等温条件下维持的贻贝中观察到的急性反应相比，对日常热应激的适应产生了对热的温和转录反应。这些结果表明 M.