Three-Generation Reproductive Toxicity of Genetically Modified Maize with Cry1Ab and epsps Genes in Rats

Ninety-Day Feeding Test of Stacked DBN9936 × DBN9501 Maize on Sprague Dawley Rats

The transgenic maize DBN9936 × DBN9501, which confers resistance to insects and tolerance to herbicides, was developed via conventional cross breeding of transgenic maize DBN9936 and DBN9501. In our present study, a 90-day feeding toxicity study was conducted on Sprague Dawley rats to evaluate the safety of the maize. A total of 140 rats were randomly assigned to seven groups (n = 10/sex/group): one control group, three genetically modified (GM) groups with 17.5%, 35%, and 70% (wt/wt) GM maize, respectively, and three non-GM groups with corresponding incorporation rate of parental maize DBN318. The rats of control group were fed with AIN93G diet. The parameters including body weights, food consumption, hematology, serum biochemistry, organ weights, and histopathology were examined during the course of the study. Compared with the non-GM group or AIN93G control group, minor statistical differences were observed for some parameters in some groups, yet none of them was considered a GM-related adverse effect. In conclusion, the results demonstrated that no adverse effect was observed on rats following 90 days feeding with diet containing up to 70% GM maize. The results indicated that stacked maize DBN9936 × DBN9501 was as safe as its parental DBN318 maize.

Effects of transgenic Bacillus Thuringiensis maize (2A-7) on the growth and development in rats

This study aimed to determine the effects of genetically modified insect-resistant maize (2A-7) on the growth and development in developing rats. Rats were fed a diet formulated with 2A-7 maize and were compared with rats fed a diet formulated with non-transgenic maize (CK group) and rats fed AIN-93G diet (BC group). 2A-7 maize was formulated into diets at ratios of 82.4% (H group) and 20.6% (L group); non-transgenic maize was formulated into diets at a ratio of 82.4%. From the first day of pregnancy, adult rats were divided into four groups and fed with the above four diets, respectively. Weaning on postnatal day 21, the diets of offspring were consistent with their parents. The results showed that body weight, hematology, serum biochemistry, organ weight, organ coefficients and allergenicity of offspring fed with 2A-7 maize were comparable with those in the CK and BC groups. In physiological and behavioral development experiments, there was no statistically significant difference among groups. Although mCry1Ab proteins were detected in organs and serum, no histopathological changes were observed among groups. In conclusion, A-7 maize cause no treatment-related adverse effects on offspring, indicating that 2A-7 maize is safe for developing rats.

Evaluation on reprogramed biological processes in transgenic maize varieties using transcriptomics and metabolomics

Genetic engineering (GM) has great potential to improve maize productivity, but rises some concerns on unintended effects, and equivalent as their comparators. There are some limitations through targeted analysis to detect the UE in genetically modified organisms in many previous studies. We here reported a case-study on the effects of introducing herbicides and insect resistance (HIR) gene cassette on molecular profiling (transcripts and metabolites) in a popular maize variety Zhengdan958 (ZD958) in China. We found that introducing HIR gene cassette bring a limited numbers of differential abundant genes (DAGs) or differential abundant metabolites (DAMs) between transgenic events and non-transgenic control. In contrast, averaged 10 times more DAGs and DAMs were observed when performed comparison under different growing environments in three different ecological regions of China than the numbers induced by gene effects. Major biological pathways relating to stress response or signaling transduction could explain somehow the effects of growing environments. We further compared two transgenic events mediated ZD958 (GM-ZD958) with either transgenic parent GM-Z58, and other genetic background nonGM-Z58, nonGM-ZD958, and Chang7-2. We found that the numbers of DAGs and DAMs between GM-ZD958 and its one parent maize variety, Z58 or GM-Z58 is equivalent, but not Chang7-2. These findings suggest that greater effects due to different genetic background on altered molecular profiling than gene modification itself. This study provides a case evidence indicating marginal effects of gene pleiotropic effects, and environmental effects should be emphasized.