Groupe Interuniversitaire en Limnologie et en Environnement Aquatique (GRIL), Département de Sciences Biologiques, Université de Montréal, Pavillon Marie-Victorin, 90 Vincent d'Indy, Montréal, QC H2V 2S9, Canada.
Groupe Interuniversitaire en Limnologie et en Environnement Aquatique (GRIL), Département des Sciences Biologiques, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montréal, QC H3C 3P8, Canada.
Sci Total Environ. 2019 Jul 20;675:604-614. doi: 10.1016/j.scitotenv.2019.04.226. Epub 2019 Apr 17.
Mercury (Hg) is a trace element of particular concern since it is ubiquitous in the environment and because its methylated form (MeHg) readily bioaccumulates and biomagnifies in food webs. This latter process leads to elevated Hg concentrations in fish and may thus induce toxicity. Maternal transfer of bioaccumulated contaminants to offspring is a suggested mechanism of impaired reproductive success in fish. The purpose of this study was to assess the toxicity potential of Hg during maternal transfer in Yellow Perch from Lake Saint-Pierre (Quebec, Canada) using a subcellular partitioning approach. We also evaluated potential protective effects of selenium, as this element has been shown to alleviate Hg toxicity through sequestration. A customized subcellular partitioning protocol was used to separate liver and gonad of Yellow Perch into various subcellular fractions. Results show that, in the liver, MeHg was primarily (51%) associated to the subcellular fraction containing cytosolic enzymes. Furthermore, 23% and 15% of MeHg was found in hepatic and gonadal mitochondria, respectively, suggesting that Yellow Perch is not effectively detoxifying this metal. There was also a strong relationship (R = 0.73) between MeHg bioaccumulation in the liver and MeHg concentrations in gonadal mitochondria, which corroborates the potential risk linked to MeHg maternal transfer. On the other hand, we also found that selenium might have a protective effect on Hg toxicity at a subcellular level. In fact, Se:Hg molar ratios in subcellular fractions were systematically above 1 in all tissues and fractions examined, which corresponds to the suggested protective threshold. This study provides the first assessment of subcellular Se:Hg molar ratios in fish. Since early developmental stages in aquatic biota are particularly sensitive to Hg, this study represents a step forward in understanding the likelihood for toxic effects in wild fish through maternal transfer.
汞（Hg）是一种特别值得关注的微量元素，因为它在环境中无处不在，而且其甲基化形式（MeHg）很容易在食物网中生物积累和生物放大。后一种过程导致鱼类中汞浓度升高，可能因此引发毒性。母体向后代传递生物积累的污染物是鱼类繁殖成功受损的一种推测机制。本研究的目的是使用亚细胞分区方法评估来自加拿大魁北克省圣皮埃尔湖的黄鲈（Yellow Perch）在母体转移过程中汞的毒性潜力。我们还评估了硒的潜在保护作用，因为已证明这种元素通过螯合作用来减轻汞毒性。使用定制的亚细胞分区方案将黄鲈的肝脏和性腺分离成不同的亚细胞部分。结果表明，在肝脏中，MeHg 主要（51%）与含有胞质酶的亚细胞部分结合。此外，MeHg 分别有 23%和 15%存在于肝和性腺线粒体中，这表明黄鲈不能有效地对这种金属进行解毒。MeHg 在肝脏中的生物积累与 MeHg 在性腺线粒体中的浓度之间也存在很强的关系（R = 0.73），这证实了与 MeHg 母体转移相关的潜在风险。另一方面，我们还发现硒可能在亚细胞水平上对汞毒性具有保护作用。事实上，在所检查的所有组织和部分中，亚细胞部分中的 Se:Hg 摩尔比都系统地高于 1，这对应于建议的保护阈值。本研究首次评估了鱼类中的亚细胞 Se:Hg 摩尔比。由于水生生物的早期发育阶段对汞特别敏感，因此本研究代表了通过母体转移了解野生鱼类发生毒性作用可能性的一个进步。
