Effects Of Transgenic CrylAb/Ac Gene Rice On The Growth And Development Of Xenopus Laevis

In the cultivated area of the transgenic Bt crop,Bt protein can be transferred through the root exudates,pollen,and crop residues,rainwater runoff and other means into the surrounding water environment.It is important to evaluate the potential risk of Bt protein to aquatic ecosystems,but the current research is scarce.In this study,we used Huahui No.1(HH1)as transgenic rice material to study its effects on the growth and development of Xenopus laevis at different developmental stages.The main contents and results are showing as follows:(1)Based on the FETAX test,CrylAb and Cry1Ac protein were added into the culture medium with three concentrations(10 mg/L,1 mg/L,0.1 mg/L).The embryonic development and deformity were recorded every 24 hours and the culture medium was replaced once.And at the end of the experiment,the activity of the tadpole was tested.The results showed that:after 96h test,embryonic development was not adversely affected in comparison with embryonic to protein or no not.The survival rate,deformity rate,body weight,body length and enzyme activity were consistent with the control group.(2)Amphibious metamorphosis is a complex process.During this time,tadpoles has undergone a series of important changes both insaide and ousaide.Tadpoles in the metamorphosis stage vulnerable to the impact of the external environment,leading to prolonged metamorphosis,serious can cause deformity,and even lead to death.At this stage,the Cry1Ab and Cry1Ac proteins were added to the culture medium to simulate the transgenic Bt gene rice field environment.Feed twice a day and observe the tadpole inventory and daily behavior.We change the culture medium every 48 h during the test.After the completion of metamorphosis,the X.laevis were anesthetized and then weighed.Finally,the Xenopus was dissected and we performed a range of biological,clinical,and pathological assessments.The results showed that:the exposure of Bt protein did not affect the growth and development of metamorphosis stage.And there was no significant difference in body weight,body length,animal behavior,organ weight,liver andkidney function,or the microstructure of some tissues between different groups.Thus,we believe that the exposure of CrylAb and CrylAc protein will not affect the normal growth and development of X.laevis during the metamorphosis stage.(3)The vertebrate intestine is a complex ecosystem of microenvironment and colonizes many microbial communities.The intestinal microflora plays an important role in the host,including the food decomposition,the metabolism,nutrient supply,improve immunity and defense against invading pathogens.In this study,we extracted the microbial metagenomic DNA and used the sequencing technology to analysis the fecal microflora of X.laevis.We found that the intestine of X.laevis.has rich flora diversity,and a total of 56 phylum and 496 genera are obtained,among which there are a large number of unidentified microorganisms.There were significant differences in microbial species and composition between different intestinal segments through diversity analysis.But in the same segment,different treatments have less effect on intestinal microbes.Thus,we conclude that the exposure of CrylAb and CryAc protein did not significantly affect the microbial composition of the intestinal microflora.(4)In fields of transgenic Bt rice,frogs are exposed to Bt proteins through consumption of both target and nontarget insects.In the present study,we assessed the risk posed by transgenic rice expressing a CrylAb/lAc fusion protein(Huahui 1,HH1)on the development of Xenopus laevis.For 90 days,froglets were fed a diet with 30%HH1 rice,30%parental rice(Minghui 63,MH63),or no rice as a control.Body weight and length were measured every 15 days.After sacrificing the froglets,we performed a range of biological,clinical,and pathological assessments.No significant differences were found in body weight(on day 90:27.7±2.17,27.4±21.40,and 27.9±1.67g for HH1,MH63,and control,respectively),body length(on day 90:60.2± 1.55,59.3±2.33,and 59.7±1.64 mm for HH1,MH63,and control,respectively),animal behavior,organ weight,liver andkidney function,or the microstructure of some tissues between the froglets fed on the HH1-containing diet and those fed on theMH63-containing or control diets.This indicates that frog development was not adversely affected by dietary intake of Cryl Ab/lAc protein.