Fisheries College, Jimei University, Xiamen, 361021, China.
Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; College of Life Sciences, Hebei University, Baoding, 071000, China.
Chemosphere. 2020 Dec;261:128160. doi: 10.1016/j.chemosphere.2020.128160. Epub 2020 Aug 28.
Up to now, complicated organoarsenicals were mainly identified in marine organisms, suggesting that these organisms play a critical role in arsenic biogeochemical cycling because of low phosphate and relatively high arsenic concentration in the marine environment. However, the response of marine macroalgae to inorganic arsenic remains unknown. In this study, Pyropia haitanensis were exposed to arsenate [As(V)] (0.1, 1, 10, 100 μM) or arsenite [As(III)] (0.1, 1, 10 μM) under laboratory conditions for 3 d. The species of water-soluble arsenic, the total concentration of lipid-soluble and cell residue arsenic of the algae cells was analyzed. As(V) was mainly transformed into oxo-arsenosugar-phosphate, with other arsenic compounds such as monomethylated, As(III), demethylated arsenic and oxo-arsenosugar-glycerol being likely the intermediates of arsenosugar synthesis. When high concentration of As(III) was toxic to P. haitanensis, As(III) entered into the cells and was transformed into less toxic organoarsenicals and As(V). Transcriptome results showed genes involved in DNA replication, mismatch repair, base excision repair, and nucleotide excision repair were up-regulated in the algae cells exposed to 10 μM As(V), and multiple genes involved in glutathione metabolism and photosynthetic were up-regulated by 1 μM As(III). A large number of ABC transporters were down-regulated by As(V) while ten genes related to ABC transporters were up-regulated by As(III), indicating that ABC transporters were involved in transporting As(III) to vacuoles in algae cells. These results indicated that P. haitanensis detoxifies inorganic arsenic via transforming them into organoarsenicals and enhancing the isolation of highly toxic As(III) in vacuoles.
迄今为止，复杂的有机胂主要在海洋生物中被发现，这表明这些生物在砷的生物地球化学循环中起着关键作用，因为海洋环境中的磷酸盐含量低，而砷的浓度相对较高。然而，海洋大型藻类对无机砷的响应仍不清楚。在这项研究中，实验室条件下将坛紫菜暴露于砷酸盐[As(V)]（0.1、1、10、100 μM）或亚砷酸盐[As(III)]（0.1、1、10 μM）中 3 天。分析了藻类细胞中的水溶性砷种类、脂溶性砷总量和细胞残渣砷含量。As(V)主要转化为氧代砷糖-磷酸盐，而其他砷化合物如单甲基化、As(III)、去甲基化砷和氧代砷糖-甘油可能是砷糖合成的中间体。当高浓度的 As(III)对坛紫菜有毒时，As(III)进入细胞并转化为毒性较小的有机胂和 As(V)。转录组结果表明，暴露于 10 μM As(V)的藻类细胞中，参与 DNA 复制、错配修复、碱基切除修复和核苷酸切除修复的基因上调，而 1 μM As(III)则上调了多个与谷胱甘肽代谢和光合作用相关的基因。大量 ABC 转运蛋白被 As(V)下调，而 10 个与 ABC 转运蛋白相关的基因被 As(III)上调，表明 ABC 转运蛋白参与将 As(III)转运到藻类细胞的液泡中。这些结果表明，坛紫菜通过将无机砷转化为有机胂并增强将高毒性的 As(III)隔离在液泡中，从而解毒无机砷。
