title: Genotoxic evaluation in Oreochromis niloticus (Fish: Characidae) of recombinant spore-crystal complexes Cry1Ia, Cry10Aa and Cry1Ba6 from Bacillus thuringiensis.
abstract: Bioinsecticides from Bacillus thuringiensis (Bt) are widely used around the world in biological control against larval stages of many insect species. Bt has been considered a biopesticide that is highly specific to different orders of insects, non-polluting and harmless to humans and other vertebrates, thus becoming a viable alternative for combating agricultural pests and insect vectors of diseases. The family of Bt δ-endotoxins are crystal-protein inclusions showing toxicity to insects' midgut, causing cell lysis leading to starvation, septicemia and death. The aim of this study is to evaluate the genotoxic potential of recombinant Bt spore-crystals expressing Cry1Ia, Cry10Aa and Cry1Ba6 on peripheral erythrocyte cells of Oreochromis niloticus, through comet assay, micronucleus (MN) test and nuclear abnormalities (NA) analysis. Fish (n = 10/group) were exposed for 96 h at 10(7) spores 30 l(-1), 10(8) spores 30 l(-1) or 10(9) spores 30 l(-1) of Bt spore-crystals. Cry1Ia showed a significant increase in comet cells at levels 1 and 2, but not at levels 3 and 4, so it was not mutagenic nor did it induce MN or NA. These three spore-crystals showed some fish toxicity at only the highest exposure level, which normally does not occur in the field.
authors.affiliation: Department of Genetics and Morphology, Institute of Biological Sciences, University of Brasilia, Brasília, DF, Brazil.
authors.forename: I S
authors.initials: IS
authors.lastname: Freire
authors.forename: A L
authors.initials: AL
authors.lastname: Miranda-Vilela
authors.forename: M L
authors.initials: ML
authors.lastname: Fascineli
authors.forename: E C
authors.initials: EC
authors.lastname: Oliveira-Filho
authors.forename: E S
authors.initials: ES
authors.lastname: Martins
authors.forename: R G
authors.initials: RG
authors.lastname: Monnerat
authors.forename: C K
authors.initials: CK
authors.lastname: Grisolia
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000737:chemistry; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000633:toxicity*; D023681:Cichlids; D003001:Cloning, Molecular; D020552:Comet Assay; D004249:DNA Damage; D004731:Endotoxins / Q000633:toxicity*; D006460:Hemolysin Proteins / Q000633:toxicity*; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D010572:Pest Control, Biological / Q000379:methods; D010575:Pesticides / Q000633:toxicity; D011994:Recombinant Proteins / Q000633:toxicity; D013171:Spores, Bacterial
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D010575:Pesticides; D011994:Recombinant Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis