Simpson R M, Newcomb R D, Gatehouse H S, Crowhurst R N, Chagné D, Gatehouse L N, Markwick N P, Beuning L L, Murray C, Marshall S D, Yauk Y-K, Nain B, Wang Y-Y, Gleave A P, Christeller J T
Horticulture and Food Research Institute, Palmerston North, New Zealand.
Insect Mol Biol. 2007 Dec;16(6):675-90. doi: 10.1111/j.1365-2583.2007.00763.x.
The midgut is a key tissue in insect science. Physiological roles include digestion and peritrophic membrane function, as well as being an important target for insecticides. We used an expressed sequence tag (EST) approach to identify candidate genes and gene families involved in these processes in the light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae). Two cDNA libraries were constructed from dissected midgut of third to fifth instar larvae. Clustering analysis of 6416 expressed sequence tags produced 1178 tentative unique genes comprising 725 tentative contigs and 453 singletons. The sequences show similar codon usage to sequences from other lepidopterans, a Kozak consensus sequence similar to Drosophila and single nucleotide polymorphisms (SNPs) were detected at a frequency of 1.35/kb. The identity of the most common Interpro families correlates well with major known functions of the midgut. Phylogenetic analysis was conducted on representative sequences from selected multigene families. Gene families include a broad range of digestive proteases, lipases and carbohydrases that appear to have degradative capacity against the major food components found in leaves, the diet of these larvae; and carboxylesterases, glutathione-S-transferases and cytochrome P450 monooxygenases, potentially involved in xenobiotic degradation. Two of the larger multigene families, serine proteases and lipases, expressed a high proportion of genes that are likely to be catalytically inactive.
中肠是昆虫学中的关键组织。其生理功能包括消化和围食膜功能，同时也是杀虫剂的重要作用靶点。我们采用表达序列标签（EST）方法，来鉴定参与浅褐苹果蛾（Epiphyas postvittana (Walker)，鳞翅目：卷蛾科）这些过程的候选基因和基因家族。从三龄至五龄幼虫解剖得到的中肠构建了两个cDNA文库。对6416个表达序列标签进行聚类分析，产生了1178个初步的独特基因，包括725个初步重叠群和453个单拷贝序列。这些序列的密码子使用情况与其他鳞翅目昆虫的序列相似，具有与果蝇相似的Kozak共有序列，并且检测到单核苷酸多态性（SNP）的频率为1.35/kb。最常见的Interpro家族的特征与中肠的主要已知功能密切相关。对选定多基因家族的代表性序列进行了系统发育分析。基因家族包括多种消化蛋白酶、脂肪酶和碳水化合物酶，它们似乎对这些幼虫食物（叶片中的主要成分）具有降解能力；还有羧酸酯酶、谷胱甘肽 - S - 转移酶和细胞色素P450单加氧酶，可能参与外源化合物的降解。两个较大的多基因家族，丝氨酸蛋白酶和脂肪酶，表达了高比例可能无催化活性的基因。
