Abstract：
Hydrogen sulphide (H2S) is considered an immunotoxicant, and its presence in the water can influence the mucosal barrier functions of fish. However, there is a significant knowledge gap on how fish mucosa responds to low environmental H2S levels. The present study investigated the consequences of prolonged exposure to sub-lethal levels of H2S on the mucosal defences of Atlantic salmon (Salmo salar). Fish were continuously exposed to two levels of H2S (low: 0.05 µM; and high: 0.12 µM) for 12 days. Unexposed fish served as control. Molecular and histological profiling focused on the changes in the skin, gills and olfactory rosette. In addition, metabolomics and proteomics were performed on the skin and gill mucus. The gene expression profile indicated that the gills and olfactory rosette were more sensitive to H2S than the skin. The olfactory rosette showed a dose-dependent response, but not the gills. Genes related to stress responses were triggered at mucosal sites by H2S. Moreover, H2S elicited strong inflammatory responses, particularly in the gills. All mucosal organs demonstrated the key molecular repertoire for sulphide detoxification, but their temporal and spatial expression was not substantially affected by sub-lethal H2S levels. Mucosal barrier integrity was not considerably affected by H2S. Mucus metabolomes of the skin and gills were unaffected, but a matrix-dependent response was identified. Comparing the high-concentration group\'s skin and gills mucus metabolomes identified altered amino acid biosynthesis and metabolism pathways. The skin and gill mucus exhibited distinct proteomic profiles. Enrichment analysis revealed that proteins related to immunity and metabolism were affected in both mucus matrices. The present study expands our knowledge of the defence mechanisms against H2S at mucosal sites in Atlantic salmon. The findings offer insights into the health and welfare consequences of sub-lethal H2S, which can be incorporated into the risk assessment protocols in salmon land-based farms.
摘要：
硫化氢（H2S）被认为是一种免疫毒素，它在水中的存在会影响鱼的粘膜屏障功能。然而,关于鱼粘膜对低环境H2S水平的反应存在显著的知识差距。本研究调查了长期暴露于亚致死水平的H2S对大西洋鲑鱼（Salmosalar）粘膜防御的影响。鱼连续暴露于两种水平的H2S（低：0.05µM；高：0.12µM）12天。未暴露的鱼作为对照。分子和组织学分析集中在皮肤的变化，ill和嗅觉玫瑰花结。此外,对皮肤和ill粘液进行了代谢组学和蛋白质组学。基因表达谱表明，g和嗅觉花环对H2S的敏感性高于皮肤。嗅觉花环显示出剂量依赖性反应，但不是the。与应激反应相关的基因在粘膜部位被H2S触发。此外，H2S引起强烈的炎症反应，特别是在ill上。所有粘膜器官都证明了硫化物解毒的关键分子库，但是它们的时间和空间表达不受亚致死H2S水平的影响。粘膜屏障完整性不受H2S的显著影响。皮肤和ill的粘液代谢组未受影响，但是确定了矩阵依赖的反应。比较高浓度组的皮肤和g粘液代谢组，确定了氨基酸生物合成和代谢途径的改变。皮肤和g粘液表现出不同的蛋白质组学特征。富集分析显示，与免疫和代谢相关的蛋白质在两种粘液基质中均受到影响。本研究扩展了我们对大西洋鲑鱼粘膜部位抗H2S防御机制的了解。这些发现为亚致死性H2S的健康和福利后果提供了见解，可以将其纳入鲑鱼陆地农场的风险评估协议。
