Short-Term Evaluation in Growing Rats of Diet ContainingBacillus thuringiensisCry1Ia12 Entomotoxin: Nutritional Responses and Some Safety Aspects

Abstract

The Cry1Ia12 entomotoxin from a Brazilian Bacillus thuringiensis strain is currently being expressed in cotton cultivars to confer resistance to insect-pests. The present study aimed to assess the effects of a diet containing Cry1Ia12 protein on growing rats. A test diet containing egg white and Cry1Ia12 (0.1% of total protein) as a protein source was offered to rats for ten days. In addition, an acute toxicity bioassay was performed in rats with a single oral dose of the entomotoxin (12 mg/animal). No adverse effects were observed in the animals receiving the test diet when compared to those receiving a control diet (egg white). The analysed parameters included relative dry weight of internal organs, duodenum histology, blood biochemistry, and nutritional parameters. The results of the acute toxicity test showed no mortality or behaviour alteration. Thus, Cry1Ia12 toxin at the tested concentration does not cause deleterious effects on growing rats when incorporated in the diet for 10 days.

Biological impact of feeding rats with a genetically modified-based diet

“…No apparent adverse effect was also reported (Sakamoto et al, 2008) in rats fed on GM soy at a level of 30% in the diet for 104 weeks. Some of the studies that reported no adverse effects in animals receiving the test diet containing the Bt Cry1Ia12 protein (Guimaraes et al, 2010) were done not only at a low concentration (0.1%) in the diet but also by feeding rats for a very short duration (10 days).…”

Transgenic Cotton Plants Expressing Cry1Ia12 Toxin Confer Resistance to Fall Armyworm (Spodoptera frugiperda) and Cotton Boll Weevil (Anthonomus grandis)

“…Previously, Grossi-de-Sa et al (2007) demonstrated that the recombinant Cry1Ia12 protein, identified in a B. thuringiensis S811 strain and expressed in Escherichia coli cells, was toxic to both cotton boll weevil larvae and fall armyworm ( S. frugiperda ). In addition, Guimarães et al (2010) performed food security assays showing that Cry1Ia12 does not have any toxic effects on mice and thus could be suitable for the production of commercial GM plant varieties.…”

Molecular Approaches to Improve the Insecticidal Activity of Bacillus thuringiensis Cry Toxins

“…Although no adverse effects of Cry toxins have been described for humans, safety assessment guidelines have been established to ensure that any product developed from GM crops are safe for human consumption [ 78 , 79 , 80 , 81 ]. Furthermore, the development of a GM plant is not only time consuming but requires previous assurances regarding the toxicity and allergenicity of the introduced foreign proteins to ensure its safety for future commercialization.…”

“…Furthermore, the development of a GM plant is not only time consuming but requires previous assurances regarding the toxicity and allergenicity of the introduced foreign proteins to ensure its safety for future commercialization. Therefore, in vivo assays using Cry1Ia12 have been performed in rats to assess its toxicity against mammals [ 81 ]. Studies using Wistar rats fed Cry1Ia12 toxin did not indicate any significant difference in total weight gain, protein digestibility or nitrogen balance in comparison to rats fed a diet without the Bt toxin.…”

“…Moreover, no differences were observed in serum protein, albumin, urea nitrogen, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase levels. Even when Cry1Ia12 was administered as a single oral dose at a concentration of 12 mg/animal, no toxicity was observed in the evaluated rats [ 81 ]. These results suggest the potential application of Cry1Ia12 toxin for the control of insect pests such as A. grandis and S. frugiperda .…”