title: The role of cysteine conjugation in the detoxification of microcystin-LR in liver of bighead carp (Aristichthys nobilis): a field and laboratory study.
abstract: The role of glutathione (GSH) and cysteine (Cys) conjugates in the detoxification of microcystin-LR (MC-LR) in bighead carp (Aristichthys nobilis) was examined under laboratory and field conditions. Wild individuals of bighead carp were collected from 5 eutrophic lakes along the Yangtze River, while in laboratory experiment, bighead carp were injected intraperitoneally with 500 μg purified MC-LR/kg body weight (bw). Contents of MC-LR and its glutathione (MC-LR-GSH) and cysteine conjugates (MC-LR-Cys) in the liver of bighead carp were determined by liquid chromatography electrospray ionization mass spectrum (LC-ESI-MS). In laboratory experiment, low concentrations of MC-LR-GSH (mean: 0.042 μg/g dry weight (DW)) were always detectable, and the mean ratio of MC-LR-Cys to MC-LR-GSH was 6.55. While, in field study, relatively high MC-LR-Cys concentration (mean: 0.22 μg/g DW) was detected, whereas MC-LR-GSH was occasionally detectable, and the average ratio of MC-LR-Cys to MC-LR-GSH was as high as 71.49. A positive correlation was found between MC-LR-Cys concentration in the liver of bighead carp and MC-LR content in seston from the five lakes (r = 0.85). These results suggest that MC-LR-Cys might be much more important than MC-LR-GSH in the detoxification of MC-LR in fish liver, and that cysteine conjugation of MC-LR might be a physiological mechanism for the phytoplanktivorous bighead carp to counteract toxic cyanobacteria.
authors: Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road 7, Wuhan 430072, People's Republic of China. zdw3296@163.com
authors: Dawen
authors: D
authors: Zhang
authors: Qiang
authors: Q
authors: Yang
authors: Ping
authors: P
authors: Xie
authors: Xuwei
authors: X
authors: Deng
authors: Jun
authors: J
authors: Chen
authors: Ming
authors: M
authors: Dai
mesh_terms: D000818:Animals; D002347:Carps / Q000378:metabolism*; D002681:China; D002853:Chromatography, Liquid; D000458:Cyanobacteria / Q000378:metabolism; D003545:Cysteine / Q000032:analysis / Q000378:metabolism*; D005978:Glutathione / Q000032:analysis / Q000378:metabolism; D008658:Inactivation, Metabolic; D060106:Lakes; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008387:Marine Toxins; D052998:Microcystins / Q000633:toxicity*
chemical_list: D008387:Marine Toxins; D052998:Microcystins; C057862:cyanoginosin LR; D005978:Glutathione; D003545:Cysteine