微囊藻毒素和脂多糖对鲢鱼和草鱼肝脏去毒相关基因活体诱导表达的影响

Transcriptional responses of detoxification-related genes in the liver of Hypophthalmichthys molitrix and Ctenopharyngodon idellus intraperitoneally injected with microcystin-LR and lipopolysaccharide

采用50μg.(kg体质量)-1的微囊藻毒素-LR(MC-LR)、2 mg.(kg体质量)-1的脂多糖(LPS)和50μg.(kg体质量)-1MC-LR+2 mg.(kg体质量)-1LPS分别活体腹腔注射鲢鱼、草鱼,采用实时荧光定量PCR方法测定MC-LR和LPS对鲢鱼、草鱼肝脏alpha-谷胱甘肽S-转移酶(GSTA)、rho-谷胱甘肽S-转移酶(GSTR)、谷胱甘肽过氧化物酶(GPX)和解偶联蛋白2(UCP2)等去毒相关基因活体诱导表达的影响.结果表明,鲢鱼、草鱼GSTA和GSTR的不同诱导变化除与两种淡水鱼类对毒素的耐受性相关外,还与毒素剂量、诱导时间等因素相关.LPS对GSTA和GSTR基因组成型、诱导型的不同作用,可能与调制因子LPS对不同生态习性淡水鱼类肝脏GST基因表达水平的调制作用不同有关.UCP2与GPX也分别在抑制过量ROS发生方面与肝脏抗氧化胁迫等方面起重要作用.

To study the transcriptional response of detoxifieation-related liver genes to mieroeystin-LR （MC-LR） and lipopolysaccharide （LPS） treatment, silver carp （Hypophthalmichthys molitrix） and grass carp （Ctenopharyngodon idellus） were respectively exposed to a single 50 μg kg^-1 body weight （bwt） dose of pure MC-LR, a single 2 mg kg^-1 bwt dose of LPS and a co-exposure MC-LR and LPS （50 jxg kg-1 bwt ＋ 2 mg kg-1 bwt）, and were then sacrificed at 24 h post-exposure. Using beta-actin （13-ACT） as external control, the relative liver alpha- and rho-class soluble glutathione S-transferase （GSTA, GSTR）, glutathione peroxidase （GPX）, and uncoupling protein 2 （UCP2） mRNA abundance of silver carp and grass carp were determined by real time-quantitative PCR. Although not significant, hepatic phase Ⅱ xenobiotic metabolizing enzyme GSTA and GSTR in response to MC-LR still play a potential role for fish in MC-LR metabolism. The different induction might relate to the tolerance of the freshwater fishes to microcystins, toxin dose, as well as exposure time. The rather complex and insignificant response of GST gene to the effect of LPS exposure, might possibly be critical to the freshwater fishes to utilize toxic blue-green algae. In addition, GPX is essential to the detoxification of cyanotoxins by providing GSH for GST, and UCP2 also has an important role in inhibiting the excessive production of ROS to restrain fish hepatocytes apoptosis.