title: Distribution and Metabolism of Bt-Cry1Ac Toxin in Tissues and Organs of the Cotton Bollworm, Helicoverpa armigera.
abstract: Crystal (Cry) proteins derived from Bacillus thuringiensis (Bt) have been widely used in transgenic crops due to their toxicity against insect pests. However, the distribution and metabolism of these toxins in insect tissues and organs have remained obscure because the target insects do not ingest much toxin. In this study, several Cry1Ac-resistant strains of Helicoverpa armigera, fed artificial diets containing high doses of Cry1Ac toxin, were used to investigate the distribution and metabolism of Cry1Ac in their bodies. Cry1Ac was only detected in larvae, not in pupae or adults. Also, Cry1Ac passed through the midgut into other tissues, such as the hemolymph and fat body, but did not reach the larval integument. Metabolic tests revealed that Cry1Ac degraded most rapidly in the fat body, followed by the hemolymph, peritrophic membrane and its contents. The toxin was metabolized slowly in the midgut, but was degraded in all locations within 48 h. These findings will improve understanding of the functional mechanism of Bt toxins in target insects and the biotransfer and the bioaccumulation of Bt toxins in arthropod food webs in the Bt crop ecosystem.
authors.affiliation: The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China. zhaozhuoyavip@163.com.
authors.forename: Zhuoya
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China. yunheli@ippcaas.cn.
authors.forename: Yunhe
authors.initials: Y
authors.lastname: Li
authors.affiliation: The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China. xiao20020757@163.com.
authors.forename: Yutao
authors.initials: Y
authors.lastname: Xiao
authors.affiliation: The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China. abid_ento74@yahoo.com.|Department of Entomology, University of Agriculture, Faisalabad 38000, Pakistan. abid_ento74@yahoo.com.
authors.forename: Abid
authors.initials: A
authors.lastname: Ali
authors.affiliation: The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China. khdhiloo@yahoo.com.|Department of Entomology, Faculty of Crop Protection, Sindh Agriculture University, Tandojam 70060, Pakistan. khdhiloo@yahoo.com.
authors.forename: Khalid Hussain
authors.initials: KH
authors.lastname: Dhiloo
authors.affiliation: The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China. wenbochenkissy@163.com.
authors.forename: Wenbo
authors.initials: W
authors.lastname: Chen
authors.affiliation: The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China. kmwu@ippcaas.cn.
authors.forename: Kongming
authors.initials: K
authors.lastname: Wu
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism*; D018556:Crops, Agricultural / Q000469:parasitology*; D004731:Endotoxins / Q000378:metabolism*; D041981:Gastrointestinal Tract / Q000378:metabolism; D003368:Gossypium / Q000469:parasitology*; D006458:Hemolymph / Q000378:metabolism; D006460:Hemolysin Proteins / Q000378:metabolism*; D008658:Inactivation, Metabolic; D007814:Larva / Q000378:metabolism; D009036:Moths / Q000196:embryology / Q000378:metabolism*; D059748:Proteolysis; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Cry1Ac; Helicoverpa armigera; tissue distribution; toxin metabolism