title: Food safety knowledge on the Bt mutant protein Cry8Ka5 employed in the development of coleopteran-resistant transgenic cotton plants.
abstract: Insecticidal Cry proteins from Bacillus thuringiensis (Bt) have been exploited in the development of genetically modified (GM) crops for pest control. However, several pests are still difficult to control such as the coleopteran boll weevil Anthonomus grandis. By applying in vitro molecular evolution to the cry8Ka1 gene sequence, variants were generated with improved activity against A. grandis. Among them, Cry8Ka5 mutant protein showed coleoptericidal activity 3-fold higher (LC50 2.83 μg/mL) than that of the original protein (Cry8Ka1). Cry8Ka5 has been used in breeding programs in order to obtain coleopteran-resistant cotton plants. Nevertheless, there is some concern in relation to the food safety of transgenic crops, especially to the heterologously expressed proteins. In this context, our research group has performed risk assessment studies on Cry8Ka5, using the tests recommended by Codex as well as tests that we proposed as alternative and/or complementary approaches. Our results on the risk analysis of Cry8Ka5 taken together with those of other Cry proteins, point out that there is a high degree of certainty on their food safety. It is reasonable to emphasize that most safety studies on Cry proteins have essentially used the Codex approach. However, other methodologies would potentially provide additional information such as studies on the effects of Cry proteins and derived peptides on the indigenous gastrointestinal microbiota and on intestinal epithelial cells of humans. Additionally, emerging technologies such as toxicogenomics potentially will offer sensitive alternatives for some current approaches or methods.
authors.affiliation: a Federal University of Ceará; Graduate Program in Biochemistry; Campus Pici ; Fortaleza , Brazil.
authors.forename: Davi F
authors.initials: DF
authors.lastname: Farias
authors.affiliation: b RIKILT Institute of Food Safety; Wageningen University and Research Center ; Wageningen , The Netherlands.
authors.forename: Ad A C M
authors.initials: AA
authors.lastname: Peijnenburg
authors.affiliation: c National Center of Genetic Resources (Embrapa-Cenargen) ; Parque Estação Biológica - PqEB; Brasília , DF , Brazil.|d Catholic University of Brasília, Graduate Program in Genomics Sciences and Biotechnology ; Asa Norte , Brasília, DF , Brazil.
authors.forename: Maria F
authors.initials: MF
authors.lastname: Grossi-de-Sá
authors.affiliation: a Federal University of Ceará; Graduate Program in Biochemistry; Campus Pici ; Fortaleza , Brazil.
authors.forename: Ana F U
authors.initials: AF
authors.lastname: Carvalho
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics* / Q000633:toxicity; D004731:Endotoxins / Q000235:genetics* / Q000633:toxicity; D059022:Food Safety; D003368:Gossypium / Q000235:genetics* / Q000469:parasitology*; D006460:Hemolysin Proteins / Q000235:genetics* / Q000633:toxicity; D006801:Humans; D007305:Insecticide Resistance; D019359:Knowledge; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000469:parasitology*; D018570:Risk Assessment; D048889:Weevils / Q000472:pathogenicity
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Anthonomus grandis; Bacillus thuringiensis; Bt crops; cytotoxicity; gastrointestinal microbiota; recombinant protein; risk assessment; toxicogenomics