Survival and growth of developing salmonids are negatively affected by low oxygen levels within gravel nests in natural streams, and hypoxic stress is often experienced by farmed Atlantic salmon (Salmo salar) within hatcheries. Exposure to hypoxia during early development may have long-lasting effects by altering epigenetic marks and gene expression in oxygen regulatory pathways. Here, we examine the transcriptomic response to low dissolved oxygen (DO) in post-hatch salmon reared continuously in 30%, 60% or 100% DO from fertilization until start of feeding. RNA sequencing revealed multiple differentially expressed genes, including oxygen transporting hemoglobin embryonic α subunit (hbae) and EGLN3 family hypoxia-inducible factor 3 (egln3) which regulates the stability of hypoxia inducible factor 1α (HIF-1α). Both hbae and egln3 displayed expression levels inversely correlated to oxygen concentration, and DNA methylation patterns within the egln3 promoter were negatively associated with the transcript levels. These results suggest that epigenetic processes are influenced by low oxygen levels during early development in Atlantic salmon to upregulate hypoxia-response genes.

发育中的鲑鱼的生存和生长受到天然溪流中砾石巢中低氧含量的不利影响，而孵化场中养殖的大西洋鲑鱼（Salmo salar）经常会遇到低氧胁迫。在早期发育中暴露于低氧状态可能会通过改变氧气调节途径中的表观遗传标记和基因表达而产生长期影响。在这里，我们研究了从受精到开始喂食，以30％，60％或100％DO连续饲养的孵化后鲑鱼对低溶解氧（DO）的转录组学响应。RNA测序揭示了多个差异表达的基因，包括氧转运血红蛋白胚胎α亚基（hbae）和EGLN3家族缺氧诱导因子3（egln3）调节缺氧诱导因子1α（HIF-1α）的稳定性。既hbae和EGLN3显示内的表达水平，以氧浓度呈负相关，和DNA甲基化模式EGLN3启动子的负转录水平相关联。这些结果表明表观遗传过程受大西洋鲑鱼早期发育过程中低氧水平的影响，以上调缺氧反应基因。