鲢鱼、鳙鱼、草鱼谷胱甘肽过氧化物酶cDNA的克隆及肝组织表达

利用RT-PCR技术分别从淡水食毒藻鱼类鲢鱼(Hypophthalmichthys molitrix)、鳙鱼(Aristichthys nobilis)及草食性鱼类草鱼(Ctenopharyngodon idella)肝组织扩增出谷胱甘肽过氧化物酶(GPX)cDNA核心序列。序列分析表明鲢鱼、鳙鱼、草鱼GPX的cDNA序列均为263bp,编码87个氨基酸。鲢鱼、鳙鱼、草鱼与斑马鱼(Danio rerio)(同属鲤科)、条石鲷(Oplegnathus fasciatus)、虹鳟(Oncorhynchus mykiss)(鲈形目)等鱼类GPX氨基酸序列同源性很高,为75%～93%;与人(Homo sapiens)、小鼠(Mus musculus)、大鼠(Rattus norvegicus)、猪(Sus scrofa)、牛(Bos taurus)等哺乳动物GPX氨基酸序列的同源性也较高,为76%～79%。以β-肌动蛋白为内参照,比较鲢鱼、鳙鱼、草鱼肝组织GPX cDNA的表达水平,鲢鱼、鳙鱼肝组织GPX的表达量远高于草鱼肝的GPX表达量,这与鲢鱼、鳙鱼大量摄入微囊藻毒素在鱼体内引发产生过量的脂过氧化物相适应。

Molecular Cloning and Tissue Expression of Glutathione Peroxidase cDNA in Hypophthalmichthys molitrix,Aristichthys nobilis and Ctenopharyngodon idella

Glutathione peroxidase(GPX) cDNAs were cloned from the livers of phytoplanktivorous freshwater fish,Hypophthalmichthys molitrix,Aristichthys nobilis,and herbivorious fish,Ctenopharyngodon idella using RT-PCR.Sequence analysis revealed that the cloned GPX cDNA fragments were all 263 bp in length,encoding 87 amino acids.Search results of the BLAST protein database revealed that the deduced amino acid sequences of Silver Carp,Bighead Carp and Grass Carp GPX were highly(75%-93%) homologous with those of other vertebrates(including Danio rerio,Oplegnathus fasciatus,Oncorhynchus mykiss,human,mouse,rat,pig and cow).Using beta-actin as control,it was showed that the GPX expression in livers form three freshwater fish species had a close relationship with their food habit,and that the expression in phytoplanktivorous fish(Silver Carp and Bighead Carp) is stronger than that in herbivorious fish(Grass Carp),suggesting that liver GPX might be important for fish to reduce lipid peroxides which are induced by microcystins.