Study On Microcystins Accumulation And Biodepuration Patterns In Procambarus Clarkii And Macrobrachium Nipponense

Microcystins(MCs), which can be accumulated in different aquatic organisms and transferred through food chain, make a potential threat to human health. Procambarus clarkii andMacrobrachium nipponense were chosen as the material to:1) analyze MC-LR accumulation and depuration patterns in different tissues; 2) investigate the effects of MC-LR on hepatopancreas damages; 3) explore the approach to reduce MC-LR content in hepatopancreas. The present study willprovide a reliable theoretical basis to revealMC-LR toxicity and detoxification studies of aquatic curstaceans.The MC-LR accumulation and depuration patterns in hepatopancreas, intestine, abdominal muscle and gill for P. clarkii and hepatopancreas, abdominal muscle for M. nipponense were analyzed with a semi-static method. The P. clarkii cat, M.nipponensecat and gst were cloned with RACE method and their tissue distribution were assayed with qRT-PCR. The antioxidant enzyme activities of superoxide dismutase(SOD), catalase(CAT), glutathione peroxidase(GPx), three-phase detoxication enzymes and transcripts of related genesin hepatopancreas were measured to reveal metabolic pathways of MC-LR. Meanwhile, the histopathology damages of hepatopancreas were investigated. In order to further explore the toxicity of the MC-LR in freshwater shrimps, high-throughput sequencing technology was employed in studying different genes expression profile of hepatopancreas.The main findings obtained are as following:1. MC-LR weremainly accumulated inintestines and hepatopancreas ofP. clarkiiandM. nipponense. After the shrimps were transferred to freshwater water without for another 7 days,the content of MC-LR was eliminated up to 80% in different tissues.2.The full-length cDNAs of cat of P. clarkii and cat, gst of M. nipponense were 1629, 1689, and 1112 bp, respectively. Their corresponding deduced amino acid numbers were 518, 518, and 217, respectively.TheirmRNAs were mainly expressed in the hepatopancreas.3.The activity and mRNA expressionof P. clarkii and M. nipponense antioxidant-related enzymes, II phase detoxification enzymes and IIIphase detoxificationenzymes were enhanced to eliminate the MC-LR content in different organisms after MC-LR exposure. Hsps genes took part in antioxidant process and hsp70 could be a biomarker for MC-LR monitoring.There were visible histopathology changes inP. clarkii and M. nipponense hepatopancreasafter MC-LR exposure.4. It was indicated that MC-LR could not only activate the genes expression which were related to glutathione metabolism pathway to reduce MC-LR stress, but also induce apoptosis with high-throughput sequencing technology analysis.In summary, we analyzed the accumulation and depuration patterns in different tissues of P. clarkiiand M. nipponense andrevealed the MC-LR eliminating approach in different organisms by antioxidant and three-phase detoxification enzymes oftwofreshwater shrimps from the enzyme activity and mRNA expression aspects. Meanwhile, histopathology changes of hepatopancreas wereexhibited to replenish the harmful effects of MC-LR.The effects of MC-LR on genes from apoptosis and glutathione metabolic pathways were also analyzed.This study will provide a reliable reference to revealMC-LR accumulation and depuration patterns in freshwater shrimps.