title: Overexpression of host plant urease in transgenic silkworms.
abstract: Bombyx mori and mulberry constitute a model of insect-host plant interactions. Urease hydrolyzes urea to ammonia and is important for the nitrogen metabolism of silkworms because ammonia is assimilated into silk protein. Silkworms do not synthesize urease and acquire it from mulberry leaves. We synthesized the artificial DNA sequence ureas using the codon bias of B. mori to encode the signal peptide and mulberry urease protein. A transgenic vector that overexpresses ure-as under control of the silkworm midgut-specific P2 promoter was constructed. Transgenic silkworms were created via embryo microinjection. RT-PCR results showed that urease was expressed during the larval stage and qPCR revealed the expression only in the midgut of transgenic lines. Urea concentration in the midgut and hemolymph of transgenic silkworms was significantly lower than in a nontransgenic line when silkworms were fed an artificial diet. Analysis of the daily body weight and food conversion efficiency of the fourth and fifth instar larvae and economic characteristics indicated no differences between transgenic silkworms and the nontransgenic line. These results suggested that overexpression of host plant urease promoted nitrogen metabolism in silkworms.
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400715, People's Republic of China.
authors.forename: Liang
authors.initials: L
authors.lastname: Jiang
authors.forename: Chunlin
authors.initials: C
authors.lastname: Huang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Sun
authors.forename: Huizhen
authors.initials: H
authors.lastname: Guo
authors.forename: Zhengwen
authors.initials: Z
authors.lastname: Peng
authors.forename: Yinghui
authors.initials: Y
authors.lastname: Dang
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Liu
authors.forename: Dongxu
authors.initials: D
authors.lastname: Xing
authors.forename: Guowen
authors.initials: G
authors.lastname: Xu
authors.forename: Ping
authors.initials: P
authors.lastname: Zhao
authors.forename: Qingyou
authors.initials: Q
authors.lastname: Xia
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D012831:Bombyx / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D004247:DNA / Q000737:chemistry; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005822:Genetic Vectors; D007814:Larva; D008297:Male; D008969:Molecular Sequence Data; D031625:Morus / Q000201:enzymology / Q000469:parasitology*; D018515:Plant Leaves / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D014508:Urea / Q000032:analysis / Q000378:metabolism*; D014510:Urease / Q000235:genetics* / Q000378:metabolism
chemical_list: D014508:Urea; D004247:DNA; D014510:Urease