Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway; Institute of Marine Research, Nordnes, Bergen, Norway.
Institute of Marine Research, Nordnes, Bergen, Norway.
Chemosphere. 2021 Sep;279:130588. doi: 10.1016/j.chemosphere.2021.130588. Epub 2021 Apr 16.
High concentrations of mercury (Hg) have been documented in deep-water fish species from some Norwegian fjords. In this study, tusk (Brosme brosme) was sampled from four locations in the innermost parts of Sognefjorden in Western Norway. Total Hg and methylmercury (MeHg) levels were measured in liver tissue. To search for potential sublethal effects of Hg, we characterized the hepatic transcriptome in tusk with high and low levels of Hg bioaccumulation using global transcriptomics analysis (RNA-seq). The results showed that there was a significant correlation between fish weight and accumulated concentrations of MeHg but not total Hg. MeHg accounted for 30-40% of total Hg in liver of most of the fish, although at concentrations above 2-3 mg Hg/kg wet weight the percentage of MeHg dropped considerably. Transcriptome analysis resulted in hundreds of differentially expressed genes in the liver of tusk with high Hg levels. Functional enrichment analysis suggested that the top affected pathways are associated with protein folding, adipogenesis, notch signaling, and lipid metabolism (beta-oxidation and phospholipids). Based on transcriptional responses pointing to well-known effects of Hg compounds in fish, the study suggests that tusk in Sognefjorden could be negatively impacted by Hg bioaccumulation.
高浓度的汞（Hg）已在挪威一些峡湾的深海水域鱼类物种中被记录到。在这项研究中，獠牙鱼（Brosme brosme）在挪威西部的松恩峡湾最深处的四个地点进行了采样。肝脏组织中测量了总汞和甲基汞（MeHg）的含量。为了寻找汞的潜在亚致死效应，我们使用全转录组分析（RNA-seq），对生物积累 Hg 水平较高和较低的獠牙鱼的肝脏转录组进行了表征。结果表明，鱼体重与 MeHg 的积累浓度之间存在显著相关性，但与总 Hg 无关。在大多数鱼类的肝脏中，MeHg 占总 Hg 的 30-40%，尽管在超过 2-3mg Hg/kg 湿重的浓度下，MeHg 的比例会大幅下降。转录组分析导致獠牙鱼肝脏中有数百个差异表达基因。功能富集分析表明，受影响最大的途径与蛋白质折叠、脂肪生成、Notch 信号和脂代谢（β-氧化和磷脂）有关。基于转录反应指向鱼类中汞化合物的已知影响，该研究表明松恩峡湾的獠牙鱼可能受到 Hg 生物积累的负面影响。
