Ocean Acidification Induces Subtle Shifts in Gene Expression and DNA Methylation in Mantle Tissue of the Eastern Oyster (Crassostrea virginica)
Ocean Acidification Induces Subtle Shifts in Gene Expression and DNA Methylation in Mantle Tissue of the Eastern Oyster (Crassostrea virginica)
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DOI：
10.3389/fmars.2020.566419
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发表时间：
2020-11-13
影响因子：
3.7
通讯作者：
Lotterhos, Katie E.
中科院分区：
文献类型：
--
作者：
Downey-Wall, Alan M.;Cameron, Louise P.;Lotterhos, Katie E.
早期证据表明，DNA甲基化可以介导海洋钙化物种对海洋酸化的表型反应。然而，很少有研究明确研究随时间推移钙化组织中的DNA甲基化。在这里，我们研究了成年东方牡蛎(Crassostrea Virgiica)暴露于实验性OA超过80天后，苍白球外液体和外套膜(钙化部位的液体和组织)的表型和分子反应。在3个试验性PCO(2)处理(“对照”，580亩ATM；“中度OA”，1,000亩ATM；“高OA”，2,800亩ATM)下饲养牡蛎，并在6个时间点(24小时-80天)取样。我们发现，高OA最初导致苍白球外液的pH值(pH(EPF))相对于外部海水的升高，在第9天达到峰值，但随着时间的推移逐渐减弱。与其他处理相比，高OA处理组的钙化率显著降低。为了探讨牡蛎如何调节苍白球外液体，在对照和高OA处理的第9天和80天的牡蛎外套膜边缘组织中检测了基因表达和DNA甲基化。随着时间的推移，外套膜组织对OA产生了显著的全球分子反应(在转录组和甲基组中)。虽然我们没有发现在OA下显著差异表达的单个基因，但pH(EPF)与几个共表达的基因簇的特征基因表达显著相关。发现了少量的OA诱导的差异甲基化位点，这与OA诱导的全基因组基因体DNA甲基化与基因表达之间的弱相关性相对应。然而，基因体甲基化与pH(EPF)相关基因簇的特征基因表达没有显著相关性。这些结果表明，OA诱导了维吉尼亚锥虫大量基因的微妙反应，但也表明在分子水平上的可塑性可能是有限的。我们的研究强调了有必要重新评估我们对海洋钙化物中组织特异性分子反应的理解，以及DNA甲基化和基因表达在介导对OA的生理和生物矿化反应中的作用。
Early evidence suggests that DNA methylation can mediate phenotypic responses of marine calcifying species to ocean acidification (OA). Few studies, however, have explicitly studied DNA methylation in calcifying tissues through time. Here, we examined the phenotypic and molecular responses in the extrapallial fluid and mantle (fluid and tissue at the calcification site) in adult eastern oyster (Crassostrea virginica) exposed to experimental OA over 80 days. Oysters were reared under three experimental pCO(2) treatments ("control," 580 mu atm; "moderate OA," 1,000 mu atm; "high OA," 2,800 mu atm) and sampled at 6 time points (24 h-80 days). We found that high OA initially induced an increase in the pH of the extrapallial fluid (pH(EPF)) relative to the external seawater that peaked at day 9, but then diminished over time. Calcification rates were significantly lower in the high OA treatment compared to the other treatments. To explore how oysters regulate their extrapallial fluid, gene expression and DNA methylation were examined in the mantle-edge tissue of oysters from days 9 and 80 in the control and high OA treatments. Mantle tissue mounted a significant global molecular response (both in the transcriptome and methylome) to OA that shifted through time. Although we did not find individual genes that were significantly differentially expressed under OA, the pH(EPF) was significantly correlated with the eigengene expression of several co-expressed gene clusters. A small number of OA-induced differentially methylated loci were discovered, which corresponded with a weak association between OA-induced changes in genome-wide gene body DNA methylation and gene expression. Gene body methylation, however, was not significantly correlated with the eigengene expression of pH(EPF)-correlated gene clusters. These results suggest that OA induces a subtle response in a large number of genes in C. virginica, but also indicate that plasticity at the molecular level may be limited. Our study highlights the need to reassess our understanding of tissue-specific molecular responses in marine calcifiers, as well as the role of DNA methylation and gene expression in mediating physiological and biomineralization responses to OA.