Mutual detoxification of mercury and selenium in unicellular Tetrahymena  

作　　者：Cheng-bin Liu Li Zhang Qi Wu Guang-bo Qu Yong-guang Yin Li-gang Hu Jian-bo Shi Gui-bin Jiang 

机构地区：[1]State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences [2]College of Resources and Environment, University of Chinese Academy of Sciences [3]Institute of Environment and Health, Jianghan University

出　　处：《Journal of Environmental Sciences》2018年第6期143-150,共8页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos.41673118 and 41422306);the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB14010400);the National Basic Research Program of China (No.2013CB430004)

摘　　要：Selenium（Se） is commonly recognized as a protective element with an antagonistic effect against mercury（Hg） toxicity. However, the mechanisms of this Hg–Se antagonism are complex and remain controversial. To gain insight into the Hg–Se antagonism, a type of unicellular eukaryotic protozoa（Tetrahymena malaccensis, T. malaccensis） was selected and individually or jointly exposed to two Hg and three Se species. We found that Se species showed different toxic effects on the proliferation of T. malaccensis with the toxicity following the order：selenite（Se（IV）） 〉 selenomethionine（SeMeth） 〉 selenate（Se（VI））. The Hg–Se antagonism in Tetrahymena was observed because the joint toxicity significantly decreased under co-exposure to highly toxic dosages of Hg and Se versus individual toxicity. Unlike Se（IV） and Se（VI）, non-toxic dosage of SeM eth significantly decreased the Hg toxicity, revealing the influence of the Se species and dosages on the Hg–Se antagonism. Unexpectedly, inorganic divalent Hg（Hg2＋） and monomethylmercury（MeHg） also displayed detoxification towards extremely highly toxic dosages of Se, although their detoxifying efficiency was discrepant. These results suggested mutual Hg–Se detoxification in T. malaccensis, which was highly dependent on the dosages and species of both elements. As compared to other species, SeM eth and MeHg promoted the Hg–Se joint effects to a higher degree. Additionally, the Hg contents decreased for all the Hg–Se co-exposed groups, revealing a sequestering effect of Se towards Hg in T. malaccensis.Selenium（Se） is commonly recognized as a protective element with an antagonistic effect against mercury（Hg） toxicity. However, the mechanisms of this Hg–Se antagonism are complex and remain controversial. To gain insight into the Hg–Se antagonism, a type of unicellular eukaryotic protozoa（Tetrahymena malaccensis, T. malaccensis） was selected and individually or jointly exposed to two Hg and three Se species. We found that Se species showed different toxic effects on the proliferation of T. malaccensis with the toxicity following the order：selenite（Se（IV）） 〉 selenomethionine（SeMeth） 〉 selenate（Se（VI））. The Hg–Se antagonism in Tetrahymena was observed because the joint toxicity significantly decreased under co-exposure to highly toxic dosages of Hg and Se versus individual toxicity. Unlike Se（IV） and Se（VI）, non-toxic dosage of SeM eth significantly decreased the Hg toxicity, revealing the influence of the Se species and dosages on the Hg–Se antagonism. Unexpectedly, inorganic divalent Hg（Hg2＋） and monomethylmercury（MeHg） also displayed detoxification towards extremely highly toxic dosages of Se, although their detoxifying efficiency was discrepant. These results suggested mutual Hg–Se detoxification in T. malaccensis, which was highly dependent on the dosages and species of both elements. As compared to other species, SeM eth and MeHg promoted the Hg–Se joint effects to a higher degree. Additionally, the Hg contents decreased for all the Hg–Se co-exposed groups, revealing a sequestering effect of Se towards Hg in T. malaccensis.

关 键 词：MERCURY SELENIUM ANTAGONISM Mutual detoxification Species 

分 类 号：X171.5[环境科学与工程—环境科学]