Differential Expression Of Bovine MICB In Pregnant Dairy Cows And Neonatal Calves

Major histocompatibility complex (MHC) is highly polymorphism, and as the messenger for T cell killer. The bovine MHC is named bovine leukocyte antigen (BoLA). According to polymorphism, MHC genes are classified as class-I, class-Ⅱand class-Ⅲ. From the research of humans and mice, MHC influences the gamete quality and embryonic development by direct or indirect immunity. MHC class I polypeptide-related sequence B(MICB) has been proved to exist in humans, pigs, and bovine MHC area. The structure of bovine MICB is similar to the heavy chain of classical BoLA-I molecules, which sends and transfers induced signal to natural killer cell. Previous research validated that MIC was certain relative signal with disease, such as heat stress, viruses or bacteria infection, especially with autoimmune disease.The aims of this test were evaluating the possible effect of MICB on the setting of dairy cow pregnancy through quantizing the expression of MICB in different trimesters and in neonatal tissues and fetal placenta. According to the reported sequences of MICB gene from GenBank, Primers of MICB was designed by the software DNAMAN according to the sequence in GenBank. PMN in replacement heifers, pregnant cows in first, second and last trimester was isolated from the dairy belonging to Shanghai Cattle Institute, and mRNA was extracted. cDNA was compounded and verified by house keeping gene ACTB. MICB expression was detected by RTq-PCR, and data was analyzed with the method of 2-△△CT.The results showed that the expression level of MICB gene changed dramatically in different periods. Comparing each period with in replacement heifers, the characteristics was as following:the expression of MICB in the first trimester was only the 25% in replacement heifers, and in the second trimester was 20% in replacement heifers. The expression ratio in peripartum than in replacement heifers was 0.8. On the calf side, the expression in fetal placenta was novel lower than in ear tissues. With these results, we suggested that there is certain relevance between MICB and the maternal-fetal immune. To the pregnant bovines, the down regulation of MICB is in favor of establishment of pregnancy, whereas the high expression was profit to fetal separating from maternal placenta and further to delivery. To the neonatal calves, low expression in placenta advanced the spalling of placenta from uterus, but upregulation in neonatal tissue could protect autoimmune response.The experiment explored the differences of MICB in different physical period, which provides molecular theory for special immune mechanism of cattle's pregnancy. It has great significance to research cattle's pregnant immunity in terms of molecular level.