重金属铅暴露对家蚕组织GSTs和GSH-Px酶活力及基因表达的影响  

Effects of Heavy Metal Lead on Activity of Glutathione S-transferase and Glutathione Peroxidase and on Expression of Related Genes in Tissues of Bombyx mori

作　　者：李艳梅[1] 袁红霞[1] 徐旭[1] 束梅影[1] 卓微伟[1] 司马杨虎[1,2] 徐世清[1,2] 

机构地区：[1]苏州大学医学部应用生物学系,江苏苏州215123 [2]现代丝绸国家工程实验室,江苏苏州215123

出　　处：《蚕业科学》2011年第3期425-434,共10页ACTA SERICOLOGICA SINICA

基　　金：苏州大学重大应用研究培育项目(No.Q3034850)

摘　　要：谷胱甘肽S-转移酶(GST)和谷胱甘肽过氧化物酶(GSH-Px)是生物体内重要的解毒酶。为了研究重金属铅对鳞翅目昆虫的影响机制,给家蚕添食Pb(NO3)2进行Pb2+暴露,用酶活测定和real-time PCR方法,调查家蚕5龄6 d幼虫不同组织中酶活性及相关基因mRNA转录水平的变化。正常家蚕5龄6 d幼虫生殖腺中的GST酶活性分别是脂肪体和中肠中的20.0倍、34.6倍,GSH-Px酶活性分别是脂肪体和中肠中的57.7倍、46.6倍。幼虫食下含10 mg/kg Pb2+以上的人工饲料时,生殖腺中2种解毒酶的活性成倍下降;人工饲料含20～80 mg/kg Pb2+时,生殖腺中的Gstd1和Gsh-Px基因mRNA转录水平也显著下调,且雄性比雌性更加显著。幼虫食下含10～160 mg/kg Pb2+的人工饲料时,脂肪体中2种解毒酶活性显著升高,Pb2+对2种酶的影响浓度分别为10～160 mg/kg和20～80 mg/kg,但在20～80 mg/kg Pb2+范围内,Gsh-Px和Gstd1基因mRNA的转录却受到抑制,并且雌性幼虫脂肪体中的GSH-Px酶活性及其基因mRNA转录水平、雄性幼虫脂肪体中的GST酶活性及基因mRNA转录水平对Pb2+暴露更加敏感。幼虫食下含20 mg/kg Pb2+以上的人工饲料时,中肠的GST酶活性显著上升,而GSH-Px酶活性变化较小,性别间差异不明显;Gstd1基因mRNA转录水平有上调趋势,Gsh-Px基因mRNA转录水平则受到显著抑制。结果显示,家蚕幼虫生殖腺虽然有比脂肪体和中肠更强的GST酶和GSH-Px酶活性,但对Pb2+的毒害敏感,雄性比雌性受影响更大,生殖腺通过抗氧化防御系统抵御Pb2+毒害的作用很弱。Glutathione S-transferase（GST） and glutathione peroxidase（GSH-Px） are important detoxifying enzymes in vivo.In order to study the influencing mechanism of heavy metal lead on lepidopterous insect,we fed the Bombyx mori with artificial diet added with Pb（NO3）2 for Pb2＋ exposure.Enzyme activity assay and real-time PCR were employed to investigate the activity of enzymes and the mRNA transcription level of related genes in tissues of day 6 larvae of the 5th instar.In normal day 6 larvae of the 5th instar,GST enzyme activity in gonad was 20.0 and 34.6 times of that in fat body and midgut respectively,and GSH-Px enzyme activity was 57.7 and 46.6 times of that in fat body and midgut respectively.After the larvae fed on artificial diet containing 10 mg/kg or higher Pb2＋,activity of the two enzymes in gonad decreased by many times.When the artificial diet contained 20 ~80 mg/kg Pb2＋,mRNA transcriptional levels of Gstd1 gene and Gsh-Px gene were also significantly down-regulated,with more significant down-regulation in males over females.After the larvae fed on artificial diet containing 10 ~160 mg/kg Pb2＋,the activity of GST and GSH-Px in fat body increased significantly.Effective Pb2＋ concentrations to these two enzymes could be divided into two ranges： 10 ~160 mg/kg and 20 ~80 mg/kg,respectively.However,within the range of 20 ~80 mg/kg Pb2＋,mRNA transcriptions of Gsh-Px and Gstd1 were inhibited.Moreover,GSH-Px activity and mRNA level of Gsh-Px in fat body of female larvae,and GST activity and mRNA level of Gstd1 in fat body of male larvae were more sensitive to Pb2＋ exposure.After 20 mg/kg or more Pb2＋ exposure,GST activity in the midgut increased dramatically,but GSH-Px activity only changed slightly and there was no significant difference between male and female larvae.mRNA transcriptional level of Gstd1 gene had a trend of up-regulation,while that of Gsh-Px was significantly down-regulated.The results suggested that,although silkworm larvae have higher enzyme activity of GST and GSH-Px

关 键 词：铅离子 家蚕组织 谷胱甘肽S-转移酶 谷胱甘肽过氧化物酶 酶活力 基因表达 

分 类 号：S884.97[农业科学—特种经济动物饲养]