Effects Of Genetically Modified Milk Containing Human Beta-defensin-3 On Digestive System And Reproductive System Of Mice

In recent years,as transgenic technology develops rapidly,it has been applied in many fields such as medicine,industry and research.In animal science,transgenic technology is mainly applied in breeding for disease resistance,developing animal bioreactor,improving product performance,and producing animal disease model.Transgenic products are potential food.The concern and debate of transgenic products are whether they are as nutritional as conventional products and have equal effects on consumer health.Based the concept of substantial equivalence and case by case basis,different countries and organisations build the regulations and rules for safety assessment of transgenic products.In general,the safety assessment of transgenic products include nutrient composition analysis,protein allergenicity analysis,and toxicity studies.The unintended effects of transgenic products should also be taken into account during the safety assessment.Thirty days or ninety days feeding studies are commonly conducted to assess toxicity,and are also the direct method to study the unintended effects of transgenic food.In order to prevent mastitis in dairy cows,human beta-defensin-3(HBD3)gene was inserted into dairy cows' genome to produce transgenic cows expressing HBD3 specifically in their mammary glands.The milk produced by these transgenic dairy cows contains HBD3.As the composition of milk was changed,we need to assess the transgenic milk is as safe as the conventional milk to achieve the integrity of transgenic technology from producing transgenic animal to safety assessment of transgenic products.Based on the above content,this study made the following research:1.C57BL/6 mice and SD rats were arranged to consume the diets with the addition of 10% or 30% transgenic milk or the conventional milk for 90 days.The general physical indexes of C57BL/6 mice and SD rats were detected,including body weight,food consumption,blood biochemistry,relative organ weight,and histopathology.The results showed there were no significant differences in body weight and food consumption of mice and rats consuming different diets(30G,30 N,10G,10 N,and C).Most of the blood biochemistry parameters were without significant differences among different groups,and although a few parameters had significant differences,all the parameters were within the normal range.The relative organ weight of different groups were without significant differences except for the relative spleen weight of the C57BL/6 male mice of 30 G group was higher than C group.No severe histopathological lesions were observed in any organ tissue sections of all groups.The transgenic milk containing HBD3 did not make adverse effects on general health of C57BL/6 mice and SD rats.2.The digestive system is the first site to contact food and plays crucial roles in metabolic reactions,nutrition absorption and immunity regulation in the host.The digestive system structure and function of C57BL/6 mice consuming diets containing transgenic milk for 90 days were dectected,including the digestibility of transgenic milk,gastric emptying function,intestinal permeability,intestinal microflora composition of mice,and the possibility of horizontal gene transfer(HGT).The results showed the transgenic milk was easy to be digested in simulated gastric fluid,and it did not have adverse effects on gastric emptying function and intestinal permeability.The microflora composition of different groups were comparable with same prominent bacteria groups.There is little possibility of HGT.3.The reproductive system is the site to produce reproductive cells,breed new individuals,and deliver the genetic information.It is the main part to assess the reproductive toxicity of transgenic products.After C57BL/6 mice consumed the diet containing transgenic milk for 90 days,the present study detected the following parameters: the relative weight of reproductive organs,the histopathology of reproductive organs,sperm abnormality,mRNA expression levels of key genes involve in spermatogenesis and follicle development.In addition,multigenerational reproduction study was conducted to assess the reprodcutive performance of mice consuming diets containing transgenic milk.The results showed there were no significant differences among different groups(30G,30 N,10G,10 N,and C)in relative reproductive organ weight,the histopathology of reproductive organs,sperm abnormality,and mRNA expression levels of cyclin A1,Usp9 Y,Wnt4,and Gdf-9 genes.The four generation of mice consuming diets containing transgenic milk were in good state of growth and development,without malformation.The reproductive performace of the parental generations and offspring did not get adverse effects.In conclusion,the transgenic milk containing HBD3 did not make adverse effects within the scope of the tests.