Early Developmental Stress Affects Subsequent Gene Expression Response to an Acute Stress in Atlantic Salmon: An Approach for Creating Robust Fish for Aquaculture?

Abstract

Stress during early life has potential to program and alter the response to stressful events and metabolism in later life. Repeated short exposure of Atlantic salmon to cold water and air during embryonic (E), post-hatch (PH) or both phases of development (EPH) has been shown to alter the methylome and transcriptome and to affect growth performance during later life compared to untreated controls (CO). The aim of this study was to investigate how the transcriptome of these fish responds to subsequent acute stress at the start feeding stage, and to describe methylation differences that might steer these changes. EPH treated fish showed the strongest down-regulation of corticotropin releasing factor 1, up-regulation of glucocorticoid receptor and 3-oxo-5-alpha-steroid 4-dehydrogenase 2 gene expression and a suppressed cortisol response 3 hr after the acute stress, differences that could influence hormesis and be affecting how EPH fish cope and recover from the stress event. Growth hormone 2 and insulin-like growth factor 1 were more strongly down-regulated following acute stress in EPH treated fish relative to E, PH and CO fish. This indicates switching away from growth toward coping with stress following stressful events in EPH fish. Genes implicated in immune function such as major histocompatibility class 1A, T-cell receptor and toll-like receptor also responded to acute stress differently in EPH treated fish, indicating that repeated stresses during early life may affect robustness. Differential DNA methylation was detected in regions mapping <500 bases from genes differentially responding to acute stress suggesting the involvement of epigenetic mechanisms. Stress treatments applied during early development therefore have potential as a husbandry tool for boosting the productivity of aquaculture by affecting how fish respond to stresses at critical stages of production.

Changes in Genome-Wide Methylation and Gene Expression in Response to Future pCO2 Extremes in the Antarctic Pteropod Limacina helicina antarctica

“…For this reason, our results do not rule out the possibility that L. helicina antarctica may differentially methylate its genome in response to presentday pCO 2 extremes. Additionally, the large effect strength of 918 µatm pCO 2 on genomic methylation in L. helicina antarctica is not unprecedented in the context of acute exposure to stress (Rodrigues et al, 2015;Li et al, 2016;Robinson et al, 2019), but the quantity of this effect should be further evaluated with replicate experiments or similar studies.…”

Harnessing genomics to fast-track genetic improvement in aquaculture

“…This potential can be harnessed by intentional environmental manipulation during crucial life stages, in particular larvae and broodstock, to improve production traits later in life and/or in subsequent generations 86,101,102 . For example, early-life use of plant-based diets improved the acceptance and utilization of these diets in later life in rainbow trout 103 , and early-life stress can modulate future stress or immune responses in Atlantic salmon, which may have implications for robustness in adult stages 104,105 . Multigenerational epigenetic effects are of most relevance to selective breeding and have been proposed to play a role in the fitness of the Manila clam (Ruditapes philippinarum), where adults exposed to low pH levels during gonadal maturation had faster-growing offspring compared with controls 106 , and in the Sydney rock oyster (Saccostrea glomerata), where larvae of parents incubated under low-pH conditions grew and developed faster in low-pH conditions and had higher fitness as adults 107 .…”

Family-effects in the epigenomic response of red blood cells to a challenge test in the European sea bass (Dicentrarchus labrax, L.)

“…Their roles were however studied in early development stages of mammals or zebrafish. As ‘epigenetic programming’ – apart of transgenerational inheritance - is mostly an early-life process that influence late-life effects (in fish, see, e.g., [ 5 , 9 , 38 , 65 ]), we thus hypothesize that the epigenetic marks that could affect them would have been already present in 6 month-old sea bass that initiated the challenge test. Developmentally induced differential methylation acquired during the challenge test seems unlikely.…”