Food Safety Assessment Of Genetically Modified Wheat With GmDREB1Gene

ObjectiveNutritional composition analysis,52-week feeding study, DGGE and PCR were employed to evaluate the chronic effects of transgenic wheat with GmDREBl gene on the performance, immunity and intestinal microflora of SD rats. The transgenic wheat was assessed in multi-aspects to provide scientific and reliable evidences for its edible safety.Methods1. Comparative analysis of nutritional composition between transgenic wheat with GmDREBl gene and its parental wheatNutritional proximates (protein, carbohydrate, fat, moisture, ash and fiber), fatty acid, amino acids, vitamins and minerals of GM wheat and non-GM wheat were analyzed to compare the nutritional composition of transgenic wheat with GmDREBl gene and its parental wheat.2. Chronic toxicity study on transgenic wheat with GmDREBl gene (52-week feeding study)Based on gender and weight,120SD rats were randomly and evenly assigned into three groups. GM wheat and non-GM wheat were separately formulated into diets at high levels. AIN-93diet was used as an additional negative control. Body weight of each animal was recorded once a week for the first13weeks, and monthly thereafter. Food consumption was determined twice a week. Hematology, serum chemistry, urinalysis and immunotoxicity were monitored at13,26and52weeks. At the end of the experiment, all surviving rats were sacrificed, organs including brain, heart, liver, spleen, kidney, adrenal, testes or ovaries were dissected and weighed. In addition to above organs, pituitary, thyroid, lung, stomach, duodenum, jejunum, ileum, colon, caecum, rectum, pancreas, prostate, urinary bladder, lymph nodes and suspected tissues were also sampled for histopathological examination.3. The effects of transgenic wheat with GmDREBl gene as feed of SD rats on intestinal microfloraFeces were collected at the adaptive phase,2weeks and52weeks of the experiment. Five feces flora (bifidobacterium, lactobacillus, enterobacter, enterococcus, clostridium perfringens) were detected with culture medium method. At13and52weeks,5male and5female rats were randomly selected from each group for feces collection. The effect of transgenic wheat with GmDREBl gene on intestinal microflora of rats was studied by denaturing gradient gel electrophoresis (DGGE) based on sequencing of16SrDNA.4. Detection of transgenic and endogenous DNA in blood, tissues and feces of ratsAt the end of the experiment, blood, liver, kidney and masseter samples were collected (5rats/sex/group) after slaughter. Total DNA was extracted form the samples and analyzed by PCR for the presence of fragments of transgenic and endogenous plant DNA.Results1. Comparative analysis of nutritional composition between transgenic wheat with GmDREBl gene and its parental wheatThere were no significant differences between the transgenic wheat and its parental wheat with respect to most of their nutritional components. Most results of nutritional components fell within the range of values reported by OECD.2. Chronic toxicity study on transgenic wheat with GmDREBl gene (52-week feeding study)Body weight and food consumption were generally similar among the three groups throughout the course of the study. We observed no significant differences in mortality rates and organ coefficients among the three groups in both sexes. There were sporadic statistically significant differences in some clinical pathology parameters between GM group and control groups. All these differences were within the historical normal range of the same laboratory.3. The effects of transgenic wheat with GmDREBl gene as feed of SD rats on intestinal microfloraBefore the experiment, there were no significant differences among the three groups in the number of colonies for bifidobacterium, lactobacillus, enterobacter and enterococcus. At2weeks, the number of bifidobacterium and lactobacillus of GM group (group A) and non-GM group (group B) were significantly higher than those of AIN group (group C). Compared with pre-experiment, the number of bifidobacterium and lactobacillus of group A and B increased significantly. At52weeks, the number of bifidobacterium and lactobacillus of group A and B were still significantly higher than those of group C. However, compared with the2nd week, the number of bifidobacterium, lactobacillus and enterococcus of the three groups decreased.PCR-DGGE polyacrylamide gel electrophoresis bands of intestinal microflora showed there were no significant differences among the three groups. DGGE maps by UPGMA cluster analysis indicated that band patterns between the GM group and non-GM group showed a high degree of similarity. At13weeks, the similarity of the two groups for males and females were>85%and>68%respectively, while at52weeks, the similarity were>80%and>88%respectively.4. Detection of transgenic and endogenous DNA in blood, tissues and feces of ratsNeither small fragments of transgenic DNA nor endogenous DNA were detected in blood, liver, kidney, masseter and feces samples from rats fed a diet containing transgenic wheat with GmDREBl gene.Conclusions1. The nutritional quality of the transgenic wheat with GmDREBl gene is substantially equivalent to its parental counterpart. The nutritional composition of the transgenic wheat does not change with the insertion of a foreign gene.2. Long-term intake of transgenic wheat with GmDREBl gene at a high level has no unintended adverse effects on rats.3. The transgenic wheat has no detrimental effects on the intestinal microflora of rats.4. Residual GmDREB1gene fragment was not detected in the body of rats.