Institute of Marine Research, Bergen, Norway.
Institute of Marine Research, Bergen, Norway.
J Hazard Mater. 2024 Jul 15;473:134699. doi: 10.1016/j.jhazmat.2024.134699. Epub 2024 May 22.
Identifying metabolism and detoxification mechanisms of Hg in biota has important implications for biomonitoring, ecotoxicology, and food safety. Compared to marine mammals and waterbirds, detoxification of MeHg in fish is understudied. Here, we investigated Hg detoxification in Atlantic bluefin tuna Thunnus thynnus using organ-specific Hg and Se speciation data, stable Hg isotope signatures, and Hg and Se particle measurements in multiple tissues. Our results provide evidence for in vivo demethylation and biomineralization of HgSe particles, particularly in spleen and kidney. We observed a maximum range of 1.83‰ for δHg between spleen and lean muscle, whereas ΔHg values were similar across all tissues. Mean percent methylmercury ranged from 8% in spleen to 90% in lean muscle. The particulate masses of Hg and Se were higher in spleen and kidney (Hg: 61% and 59%, Se: 12% and 6%, respectively) compared to muscle (Hg: 2%, Se: 0.05%). Our data supports the hypothesis of an organ-specific, two-step detoxification of methylmercury in wild marine fish, consisting of demethylation and biomineralization, like reported for waterbirds. While mass dependent fractionation signatures were highly organ specific, stable mass independent fractionation signatures across all tissues make them potential candidates for source apportionment studies of Hg using ABFT.
鉴定生物体内汞的代谢和解毒机制对于生物监测、生态毒理学和食品安全都具有重要意义。与海洋哺乳动物和水鸟相比，鱼类中对甲基汞的解毒作用研究较少。在这里，我们使用器官特异性汞和硒形态分析、稳定汞同位素特征以及多种组织中的汞和硒颗粒测量，研究了大西洋金枪鱼（Thunnus thynnus）的汞解毒作用。我们的研究结果为体内汞硒颗粒的去甲基化和生物矿化提供了证据，特别是在脾脏和肾脏中。我们观察到脾脏和瘦肌肉之间的δHg 值最大范围为 1.83‰，而所有组织的 ΔHg 值相似。甲基汞的平均百分比范围从脾脏中的 8%到瘦肌肉中的 90%。与肌肉相比，汞和硒的颗粒质量在脾脏和肾脏中更高（汞：分别为 61%和 59%，硒：分别为 12%和 6%）。我们的数据支持了一个关于野生海洋鱼类中甲基汞的器官特异性两步解毒假说，包括去甲基化和生物矿化，这与水鸟的报道相似。虽然质量依赖的分馏特征具有高度的器官特异性，但所有组织中稳定的质量独立分馏特征使它们成为使用 ABFT 进行汞源分配研究的潜在候选物。
