Toxicological Studies On The Food Safety Of Two Transgenic Rice

Rice (Oryza sativa L.) is one of the most important crops in our country, and it is used to feed half of the world population, as a result there are concerns on the quality of rice consumed by people. Genetic engineering technology can be used to improve the nutritional and functional value of traditional rice, but there are some controversies on the usage of this technology with regards to the safety of transgenic rice. Therefore studying the food safety of transgenic rice and providing scientific basis for the development of transgenic rice is of great significance.Transgenic rice lines expressing GL fusion protein gene and double antisense branching enzymes gene were used in this study. Through the systematic toxicological research, the safety of the two transgenic rice were assessed in order to provide reference for the evaluation of food safety with regard to transgenic rice. The main research contents and results are as following:1. The acute toxicity study of the transgenic rice expressing double antisense branching enzymes gene. The mice were observed for 14 days following acute oral exposure at a dose of 2.15,4.64,10.00 and 21.50g/kg of body weight. The results indicated that no adverse toxic effect appeared in mice growth. There were no significant differences in the body weight, haematology, organ relative weights and histopathology in the different groups. So this transgenic rice can be classified as a nontoxic rice.2. The mutagenicity study of the transgenic rice expressing double antisense branching enzymes gene. On the mutagenicty study the following test were conducted: mice bone marrow cell micronucleus test, mice sperm abnormality test, Ames test and fluctuation test. Test results gave no indication that this transgenic rice possessed any mutagenic potential.3. The teratogenicity toxicology study of the transgenic rice expressing double antisense branching enzymes gene. The rats were fed with genetically modified rice feed, while pregnant rats and their fetuses development were studied. The results indicated that no adverse effect were observed on the body weight gain and fecundity of pregnant rats and fetuses growth (appearance, viscera and bone), the transgenic rice expressing double antisense branching enzymes gene have no teratogenesis on test rats.4. The ninety days feeding study of the transgenic rice expressing double antisense branching enzymes gene. The rats were fed with genetically modified rice feed and was analysed on the basis of the rats body weight, food consumption, water intake, hematology, serum chemistry, urinalysis, serum sex hormoneorgan, organ weight, ratio and pathology. The results showed that there were no significant differences in the transgenic rice group compared with the non-transgenic rice group, some statistical differences were observed in the transgenic rice group compared with the control diet, but it were not considered biologically significant or related to exposure to the transgenic rice.5. The three generation study of two transgenic rice. The three generation experiment of the two transgenic rice were studied on rats, some parameters were observed such as reproductive parameters for F0, F1 and F2 pregnant rats (including copulation index, fertility index, gestation length and live-birth rate), F1, F2 and F3 offspring (including viability index at birth, number of pups birth, sex ratio of pups, body weight, body length, tail length and anogenital distance at birth), body weight and food consumption during the pre-mating, gestation and lactation periods, hematology and serum chemistry for adult rats, organ ratio and pathology for litters after weanlings and adult rats. The results indicated that small serum chemistry and organ ratio parametersshowed statistical differences, this was found mostly in the transgenic rice group compared with the control rice. These differences had random dispersion and no gender unity, so it was not considered biologically significant. Therefore this form of transgenic rice have no adverse effect on the reproductive abilities of the rats.6. The reproductive study of two transgenic rice. The rats were fed with genetically modified rice feed, this was analysed based on estrous cycle and antioxidant capacity of the ovarian tissue of the female rats, number of sperm and morphologically abnormal sperm, testicular cells cycle for male rats, serum sex hormoneorgan, anogenital distance, reproductive organs ratio and the pathology of the male and female rats. The results revealed that no statistical difference was observed in the transgenic rice group compared with the non-transgenic rice group. The small parameters (testicular cells cycle and reproductive organs ratio) have statistical differences in the transgenic rice group compared with the control rice, but it were not considered biologically significant. Therefore this transgenic rice have no adverse effect on the structure and the function of the reproductive system of the rats.7. The immunotoxicity study of the transgenic rice expressing GL fusion protein gene. The immunotoxicologic and immunogenic experiment of the transgenic rice expressing GL fusion protein gene were studied on balb/c mice, this was analysed on the bases the rats hematology, lymphocyte subsets, delayed type hypersensitivity (DTH), T lymphocyte transformation induced by ConA, hemolysin level, phagocytosis ratio of peritoneal macrophages, immune organs ratio and exogenous protein detection. The findings of this study showed no statistical difference was observed in the transgenic rice group compared with the non-transgenic rice group and as well as the control diet. Moverover, the exogenous protein of the transgenic rice were not detected in the animal organs and their feces consequently, no immunotoxicity was observed on mice fed with transgenic rice this indicates that exogenous protein of transgenic rice can be digested completely and have no immunogenicity.