Food Safety Assessment Of Genetically Modified Milk With Human ?-defensin-3 Gene

Transgenic technology has been utilized in biomedical research of all field s and plays an essential role in resistance breeding of animals.Transgenic cow that could naturally encode HBD-3 has been a research focus in recent decad es and showed remarkable potential in disease-resistance and nutrition.While c onsidering the lack of study on the biosafety of transgenic milk might restrict its further applications,it was necessary to evaluate the biosafety of transgenic milk that would benefit its promotion from lab to life.The study was designed to evaluate potential influence exerted by transgen ic milk according to the conception of Sbustantial equivalence issued by FAO/WHO and the procedures for toxicological assessment of food issued by Mini stry of Health of PRC.Subchronic toxicity testing with GM milk included da ily ration on C57 mice were continued for 90 days.On basis of different GM milk ratio of ration,mice were divided into 3 experimental groups,GM-milk ration group,non-GM-milk ration group and milk-free ration group.Mice from different groups were weighed every 15 days and the growth curve was plotte d accordingly.After the 90-day period,all mice were slaughtered and weight o f their uterus,ovary,testis,epidymis as well as their body were recorded and the organ coefficiency index were calculated.Further morphological observation,tissue section and sperm count were conducted to study any modification on mice reproductive system.Reproductive hormones in serum were determined us ing RIA.Evaluation on genetic level was based on a real-time PCR analyzingspecific gene expression.And Estrous cycle of mice was detected through vagi na observation and smear observation of vagina cells specially in female mice.Then the results were as follows:1.The body weight of GMM group was slightly higher than milk-free grou p.While the average weight of mice from each group were within rational we ight range which indicated no statistically significant difference.Morphology,pos ition and size of major reproductive organs maintained regular.No pathological change and statistical difference were observed in both tissue section and sper m count.2.Reproductive hormones in serum were determined using RIA and obser ved no significant differences among three groups.3.Evaluation on reproductive function related gene and cancer-related gene expression level also reflected no difference among three groups.4.A total 5-6 days of estrous cycle showing correspondence with normal mice further confirmed the biosafety of GM milk.Conclusion:The results demonstrated that the short-term feed trials with H BD-3 milk exerted no significant influence on growth of mice reproductive org ans,reproductive hormone in serum,reproductive function related gene,cancerrelated gene and estrus cycle.This subchronic toxicity test on C57 mice furthe r reflected that HBD-3 milk was proved safe to reproductive system of mice.