Abstract

There is clear evidence that the oceans are warming due to anthropogenic climate change, and the northeastern coast of USA contains some of the fastest warming areas. This warming is projected to continue with serious biological and social ramifications for fisheries and aquaculture. One species particularly vulnerable to warming is the Atlantic surfclam (Spisula solidissima). The surfclam is a critically important species, linking marine food webs and supporting a productive, lucrative, and sustainable fishery. The surfclam is also emerging as an attractive candidate for aquaculture diversification, but the warming of shallow coastal farms threatens the expansion of surfclam aquaculture. Little is known about the adaptive potential of surfclams to cope with ocean warming. In this study, the surfclam transcriptome under heat stress was examined. Two groups of surfclams were subjected to heat stress to assess how artificial selection may alter gene expression. One group of clams had been selected for greater heat tolerance (HS) and the other was composed of random control clams (RC). After a 6-h exposure to 16 or 29 °C, gill transcriptome expression profiles of the four temperature/group combinations were determined by RNA sequencing and compared. When surfclams experienced heat stress, they exhibited upregulation of heat shock proteins (HSPs), inhibitors of apoptosis (IAPs), and other stress-response related genes. RC clams differentially expressed 1.7 times more genes than HS clams, yet HS clams had a stronger response of key stress response genes, including HSPs, IAPs, and genes involved with mitigating oxidative stress. The findings imply that the HS clams have a more effective response to heat stress after undergoing the initial selection event due to genetic differences created by the selection, epigenetic memory of the first heat shock, or both. This work provides insights into how surfclams adapt to heat stress and should inform future breeding programs that attempt to breed surfclam for greater heat tolerance, and ultimately bring greater resiliency to shellfish farms.

中文翻译：

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大西洋北蛤（Spisula Solidissima）对急性热应激的转录组反应

摘要

有明确证据表明，由于人为气候变化，海洋正在变暖，而美国东北海岸包含一些变暖最快的地区。预计这种变暖将持续下去，对渔业和水产养殖业产生严重的生物和社会影响。一种特别容易受到变暖影响的物种是大西洋蛤（Spisula Solidissima）。北蛤是一种极其重要的物种，它连接着海洋食物网并支持高产、利润丰厚且可持续的渔业。北蛤也正在成为水产养殖多样化的一个有吸引力的候选者，但浅海沿海养殖场的变暖威胁着北蛤水产养殖的扩张。人们对冲浪蛤应对海洋变暖的适应潜力知之甚少。在这项研究中，研究了热应激下的北蛤转录组。两组北蛤受到热应激，以评估人工选择如何改变基因表达。选择一组具有较高耐热性（HS）的蛤，另一组由随机对照蛤（RC）组成。暴露于 16 或 29 °C 6 小时后，通过 RNA 测序确定并比较四种温度/组组合的鳃转录组表达谱。当北蛤经历热应激时，它们表现出热休克蛋白（HSP）、细胞凋亡抑制剂（IAP）和其他应激反应相关基因的上调。RC 蛤的差异表达基因比 HS 蛤多 1.7 倍，但 HS 蛤对关键应激反应基因的反应更强，包括 HSP、IAP 和与减轻氧化应激有关的基因。研究结果表明，由于选择产生的遗传差异、第一次热休克的表观遗传记忆或两者兼而有之，HS蛤在经历初始选择事件后对热应激有更有效的反应。这项工作提供了有关北蛤如何适应热应激的见解，并为未来尝试培育北蛤以提高耐热性的育种计划提供信息，并最终为贝类养殖场带来更大的恢复能力。