Abstract：
Recently, elevated seawater temperatures have resulted numerous adverse effects, including significant mortality among bivalves. The dwarf surf clam, Mulinia lateralis, is considered a valuable model species for bivalve research due to its rapid growth and short generation time. The successful cultivation in laboratory setting throughout its entire life cycle makes it an ideal candidate for exploring the potential mechanisms underlying bivalve responses to thermal stress. In this study, a total of 600 clams were subjected to a 17-day thermal stress experiment at a temperature of 30 °C which is the semi-lethal temperature for this species. Ninety individuals who perished initially were classified as heat-sensitive populations (HSP), while 89 individuals who survived the experiment were classified as heat-tolerant populations (HTP). Subsequently, 179 individuals were then sequenced, and 21,292 single nucleotide polymorphisms (SNPs) were genotyped for downstream analysis. The heritability estimate for survival status was found to be 0.375 ± 0.127 suggesting a genetic basis for thermal tolerance trait. Furthermore, a genome-wide association study (GWAS) identified three SNPs and 10 candidate genes associated with thermal tolerance trait in M. lateralis. These candidate genes were involved in the ETHR/EHF signaling pathway and played pivotal role in signal sensory, cell adhesion, oxidative stress, DNA damage repair, etc. Additionally, qPCR results indicated that, excluding MGAT4A, ZAN, and RFC1 genes, all others exhibited significantly higher expression in the HTP (p < 0.05), underscoring the critical involvement of the ETHR/EHF signaling pathway in M. lateralis\' thermal tolerance. These results unveil the presence of standing genetic variations associated with thermal tolerance in M. lateralis, highlighting the regulatory role of the ETHR/EHF signaling pathway in the bivalve\'s response to thermal stress, which contribute to comprehension of the genetic basis of thermal tolerance in bivalves.
摘要：
最近,海水温度升高导致了许多不利影响，包括双壳类动物的显著死亡率。矮人冲浪蛤仔，外侧Mulinialateralis,由于其快速生长和较短的生成时间，被认为是双壳类动物研究的有价值的模型物种。在整个生命周期中在实验室环境中的成功培养使其成为探索双壳类动物对热应力反应的潜在机制的理想候选者。在这项研究中,在30°C的温度下，对总共600只clam进行了17天的热应力实验，这是该物种的半致死温度。最初死亡的90个人被归类为热敏感人群（HSP），而在实验中幸存的89人被归类为耐热人群（HTP）。随后，然后对179个人进行了测序，并对21,292个单核苷酸多态性（SNPs）进行基因分型，用于下游分析。发现生存状态的遗传力估计值为0.375±0.127，这表明了耐热性性状的遗传基础。此外，一项全基因组关联研究(GWAS)确定了3个SNPs和10个候选基因与外侧分枝杆菌的耐热性性状相关.这些候选基因参与了ETHR/EHF信号通路,在信号感觉、细胞粘附，氧化应激，DNA损伤修复,等。此外,qPCR结果表明,不包括MGAT4A，ZAN,和RFC1基因，所有其他在HTP中表现出显著较高的表达(p<0.05)，强调ETHR/EHF信号通路在外侧分枝杆菌热耐受性中的关键参与。这些结果揭示了外侧分枝杆菌中与耐热性相关的常设遗传变异的存在，强调ETHR/EHF信号通路在双壳类动物对热应激反应中的调节作用，这有助于理解双壳类动物耐热性的遗传基础。
