Different Detection Methods Of The Caprine Placental Lactogen And Its Localization In Placenta Tissue

The placenta plays a critical role in providing an environment that supports optimal fetal growth. It does this by providing the site of nutrient transfer from the mother to the fetus and waste secretion from the fetus to the mother, acting as a barrier against pathogens and the maternal immune system, and as an active endocrine organ capable of secreting hormones, growth factors, cytokines, and other bioactive products. Ruminant placental lactogen (PL) are members of the somatotropin, prolactin gene family that are synthesized by trophectodermal binucleate cells.The structure and biology of PL has been studied in the cow, sheep, and goat. Ruminant PL have greater structural identity to prolactin than somatotropin, although they bind to both lactogenic and somatogenic receptor. The molecular weights of caprine and ovine placental lactogen (cPL) is appromimately 23 000Da, whereas bovine placental lactogen is larger(31 000Da to 34 000Da)due to glycosylation. Placental lactogen is secreted into both the fetal and maternal circulations. The concentration of PL in the fetus decreases with advancing gestation, whereas PL concentration peaks in the maternal circulation during the last third of pregnancy then reaches a plateau. Furthermore, the maternal concentration of PL is 100- to 1000-fold higher in goats and sheep than in cows. The precise factors that modulate secretion of are unknown, although placental mass and nutrition seem to play a role.In our experiment, the placenta tissue and blood sample used were obtained from slaughter or by cesarean section.In order to identify the kind of the cell and the component of the cell,common optical microscope and transmitter electron microscope were used to observe the morphous of the all kind of cells in the placental tisse espically mononucleate and binucleate trophoblast cells. SDS-PAGE was used to detect the expression of the protein in the placenta;RT-PCR was used to find if there're cPL mRNA in the placental tissue and maternal blood plasma.Polyclonal antibody of recombiant caprine placental lactogen (rcPL) was prepared, then used to localize caprine placental lactogen in caprine placenta. Polyclonal antibody was prepared in 6 to 8 week-old Kunming mouse. Serum was collected six days after third boost immunization ,and the concentration of antiserum was detected with agar gel immunodiffusion(AGID) and indirect enzyme-linked immunosorbent assay(ELISA) .Placental tissue were obtained after delivery by caesarean section and placental lactogen was localized with antiserum by the methods of Immunohistochemistry and indirect fluorescence antibody assay (IFA). The antigen could be detected at a concentration of 100μg/ml by the method of AGID, and the P/N data was 7.77 with the method of ELISA ;it was obvious that the caprine placental lactogen was expressed in the binucleate and uninucleate cells of the caruncles and cotyledons by immunohistochemical and immunofluorecence methods. Conclusion: It was possible to raise polyclonal antibody of rcPL in the Kunming mouse by injecting subcutaneously in multiple sites along the back, and the preparative antibody could be used to examine PL in placenta by the methods of IHC and IFA.