棉铃虫6龄幼虫中肠与脂肪体微粒体P450酶系的比较  

COMPARISON OF MICROSOMAL P450 MONOOXYGENASES IN MIDGUT AND FATBODY TISSUES OF 6TH INSTAR LARVAE OF COTTON BOLLWORM (HELICOVERPA ARMIGERA)

作　　者：邱星辉[1] 李薇[1] 冷欣夫[1] 

机构地区：[1]中国科学院动物研究所农业虫害鼠害综合治理研究国家重点实验室,北京100080

出　　处：《动物学报》2002年第2期208-212,共5页ACTA ZOOLOGICA SINICA

基　　金：国家自然科学基金资助项目 (No .396 70 491)

摘　　要：报道了棉铃虫 6龄幼虫中肠和脂肪体微粒体P45 0酶系的组成与加单氧酶活性。与脂肪体微粒体相比 ,中肠微粒体具有更高的细胞色素P45 0、细胞色素b5和NADPH -细胞色素P45 0还原酶含量 ,表现出较高的艾氏剂环氧化酶和对 -硝基苯甲醚O -脱甲基酶活性。SDS PAGE电泳显示 ,中肠与脂肪体微粒体介于P45 0分子量范围内 (4 5～ 6 0kDa)的蛋白图谱有所不同 ,反映出中肠和脂肪体微粒体蛋白组成存在差异。通过对 -硝基苯甲醚O -脱甲基酶的动力学分析发现脂肪体微粒体的对 -硝基苯甲醚O -脱甲基酶对底物有更强的亲和性 ,表明不同组织来源的P45 0同功酶存在质的不同。Cotton bollworm ( Helicoverpa armigera ) is a major pest of many agricultural plants around the world. The explosion of the cotton bollworm populations is mainly attributed to its tolerance of an adverse chemical environment. The major enzyme involved in the primary detoxification pathway of insecticide and other exogenous compounds in general is cytochrome P450 monooxygenases. To better understand the biochemical property of these monooxygenases, we assayed the components of P450 monooxygenase electron transport systems and some activities of the microsomal P450 monooxygenases in the two main detoxification tissues (fatbody and midgut) of 6th instar larvae of cotton bollworm by spectrophotometry and gas chromatography. The results were compared between the two tissues. The microsomal pellet from larval midgut was even, while that from larval fatbody was separated as two fractions: the upper layer (Fraction Ⅰ) contained the majority of the microsomal proteins and preserved more than 90% of monooxygenase activities. The technical problem in determination of cytochrome P450 and b5 contents caused by the milk like fatbody microsomal preparation could be overcome if excluding fraction Ⅱ from the preparations. Compared with fatbody microsome, the midgut microsome contained significantly higher levels of cytochrome P450 (2 14 fold), b5 (2 62 fold) and NADPH cytochrome P450 reductase (2 00 fold) and showed significantly higher aldrin epoxidation (2 73 fold) and p nitroanisole demethylation (1 78 fold). The assay results of the contents and the activities of the monooxygenases indicate that midgut plays very important roles in the metabolism of foreign compounds in cotton bollworm. The differences of monooxygenases in midgut and fatbody were observed in kinetic parameters and SDS PAGE patterns. The Km of p nitroanisole O demethylase from fatbody (0 1648 mmol/L) was much lower than that from midgut (3 8498 mmol/L), which indicates that fatbody microsomes have stronger affinity to the substrate p ni

关 键 词：6龄幼虫 微粒体 P450酶系 比较 棉铃虫 中肠 脂肪体 细胞色素P450 加单氧酶 

分 类 号：S435.622.3[农业科学—农业昆虫与害虫防治]