Epigenetic mechanisms such as DNA methylation have the potential to affect organism acclimatization and adaptation to environmental changes by influencing their phenotypic plasticity; however, little is known about the role of methylation in the adaptive phenotypic divergence of marine invertebrates. Therefore, in this study, a typical intertidal species, the Pacific oyster ( Crassostrea gigas ), was selected to investigate the epigenetic mechanism of phenotypic plasticity in marine invertebrates. Intertidal and subtidal oysters subjected to one-generation common garden experiments and exhibited phenotypic divergence were used. The methylation landscape of both groups of oysters was investigated under temperate and high temperature. The two tidal oysters exhibited divergent methylation patterns, regardless of the temperature, which was mainly original environment-induced. Intertidal samples exhibited significant hypomethylation and more plasticity of methylation in response to heat shock, while subtidal samples showed hypermethylation and less plasticity. Combined with RNA-seq data, a positive relationship between methylation and expression in gene bodies was detected on a genome-wide scale. In addition, approximately 11% and 7% of differentially expressed genes showed significant methylation variation under high temperatures in intertidal and subtidal samples, respectively. Genes related to apoptosis and organism development may be regulated by methylation in response to high temperature in intertidal oysters, whereas oxidation-reduction and ion homeostasis-related genes were involved in subtidal oysters. The results also suggest that DNA methylation mediates phenotypic divergence in oysters adapting to different environments. This study provides new insight into the epigenetic mechanisms underlying phenotypic plasticity in adaptation to rapid climate change in marine organisms.

中文翻译：

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DNA甲基化介导不同潮汐水平的太平洋牡蛎（Crassostrea gigas）的热反应分化

DNA甲基化等表观遗传机制有可能通过影响其表型可塑性来影响生物体的驯化和适应环境变化；然而，关于甲基化在海洋无脊椎动物适应性表型分化中的作用知之甚少。因此，本研究选择典型的潮间带物种太平洋牡蛎（Crassostrea gigas）来研究海洋无脊椎动物表型可塑性的表观遗传机制。使用经过一代普通花园实验并表现出表型差异的潮间带和潮下带牡蛎。在温带和高温下研究了两组牡蛎的甲基化景观。无论温度如何，这两种潮汐牡蛎都表现出不同的甲基化模式，这主要是原始环境引起的。潮间带样品在响应热休克时表现出显着的低甲基化和更高的甲基化可塑性，而潮下带样品表现出高甲基化和较低的可塑性。结合 RNA-seq 数据，在全基因组范围内检测到甲基化与基因体表达之间的正相关关系。此外，大约 11% 和 7% 的差异表达基因在高温下分别在潮间带和潮下带样品中表现出显着的甲基化变异。潮间带牡蛎中与细胞凋亡和生物体发育相关的基因可能受到甲基化的调控，以响应潮间带牡蛎的高温，而氧化还原和离子稳态相关基因参与潮下带牡蛎。结果还表明，DNA甲基化介导牡蛎适应不同环境的表型差异。这项研究为海洋生物适应快速气候变化的表型可塑性背后的表观遗传机制提供了新的见解。