Safety Assessment Of Two Bt Proteins And Transgenic Cry1C Rice For Zebrafish(Danio Rerio)

With the large-scale planting of transgenic Bt crops,more and more GM crops and their residues enter the aquatic ecosystem.As a result,Bt proteins can enter into adjacent water environment,and non-target aquatic organisms will be exposed to Bt proteins.Fish is one of the most important biological components in aquatic ecosystems,playing an important ecological function,and it is important to understand the impacts of Bt crops on fish.In the present study,we selected zebrafish as a representative species of fish,studied the effects of two purified Bt proteins(Cry1C,Cry2A)on zebrafish embryos under laboratory conditions.Furthermore,we made diets containing T1C-19 rice to feed juvenile zebrafish for 90 days,and their effects on the growth and development of zebrafish were evaluated.Moreover,we analyzed the effects of Bt crops on fish by Meta-analysis.The main results are showing as follows:(1)The zebrafish embryos were exposed to E3 embryo culture medium containing different concentrations of purified Cry1 C and Cry2 A protein until 132 hpf,and then several developmental,biochemical,and molecular parameters were evaluated.Chlorpyrifos,a known toxicant to aquatic organisms,was used as a positive control,and E3 medium alone was used as a negative control The results showed that both of the two Bt proteins had no negative effects on embryonic development(hatching rate,survival rate,malformation rate,body length,etc.)and physiological and biochemical indexes of zebrafish,while the growth and development of zebrafish embryos in the positive control group were significantly inhibited.(2)To evaluate the effect of transgenic cry1 C rice(T1C-19)on zebrafish from juvenile to adult,we made diets containing T1C-19 rice and its parent rice MH63 by measuring the nutrient composition of marketed zebrafish feed and T1C-19 rice grain.A 90-day zebrafish feeding test was performed,and then the growth and development parameters of zebrafish,activities of intestinal digestive and antioxidant enzymes,and intestinal microbial diversity were observed and tested.The results showed that the transgenic cry1 C rice has no significantly adverse effects on zebrafish growth and development,intestinal microbes diversity.(3)Based on the published studies about the effects of Bt crops on aquatic organisms,we found that the current research mainly focuses on Bt corn,while the research on Bt rice is relatively rare.We established the database by integrating the literature data on the effects of Bt corn on aquatic organisms.The aquatic organisms were divided into three groups(fish,aquatic insects,crustaceans)for meta-analysis.The results showed that Bt corn had no negative impact on fish growth and development,organ index,physiological and biochemical indicators.While,Bt corn has a negative impact on the development of the Trichoptera insects and Daphnia magna,but has no effect on their survival.