Vascular endothelial growth factor (VEGF) is a specific mitogen of endothelial cells and plays an important role in vasculogenesis and angiogenesis. In recent years, both our and other laboratories have found that VEGF may be involved in embryo implantation. However, the relationship between VEGF and MMP-2 and MMP-9, the marker molecules of embryo implantation, is still unknown. In the present study, an examination of the effects of VEGF on the expression and secretion of MMP-2 and MMP-9 during implantation in mice was carried out by RT-PCR and gelatin zymography. The results show that VEGF antibody significantly decreased uterine mRNA levels of MMP-2 and MMP-9 during pregnancy, and that VEGF could up-regulate the activities of MMP-2 and MMP-9 secreted by blastocysts cultured in vitro in a time- and dose-dependent manner. The results suggest that, in the course of implantation, the ability for metastasis and invasion of blastocysts and the receptive-ness of the uterus might be regulated by VEGF
LI SuminCAO YujingZHANG JianTIAN YongqiangZHENG XingDUAN Enkui
The spectrum of antimicrobial effects of melittin were investigated on 19 pathogens by using a cylin-der-plate method with serial dilutions. Bacteriostatic efficiency and possible mechanistic effects were monitored via growth curves. The mechanism of inhibition was further analyzed by SDS-PAGE, flow cytometry and electron microscopy. Melittin had a wide inhibition spectrum and killed pathogens ef-fectively, and bacteriostatic action was influenced by factors such as pH and temperature. We eluci-dated three inhibitory mechanisms: melittin integrated with the cell membrane causing cell bursting and cytoplasm release, inhibited the synthesis of proteins and caused the cytoplasm to condense, and delayed pathogens in phase I (or phase G1) so that they could not complete the cell cycle. These re-sults suggest that melittin could serve as a broad-spectrum biological pesticide with fast-action and high-efficiency.
PAN LingZi NA Jie XING Zhuo FANG HongJun WANG GuanLin
The high failure rate of interspecific pregnancy is a major obstacle to the successful interspecific cloning of mammals. To investigate the reasons for the failure of inter-specfic pregnancy between rats and mice, we transferred rat blastocysts into mouse uteri on the third day of pseudopreg-nancy (D3). Our previous study showed that intact rat em-bryos could still be observed in mouse uteri on D9. In the present study, we found that expression of CD57 and CD68 increased significantly at the maternal-fetal interface fol-lowing the transfer of rat embryos. Similarly, Leukaemia inhibitory factor (LIF) expression increased, but vascular endothelial growth factor (VEGF) expession decreased. In a co-culture system, the percentage of rat ectoplacental cones (EPCs) with adhesion and outgrowth and outgrowth area on mouse uterine decidual cells were less than that of mouse EPCs. These results indicate that an increase in the immu-nological rejection response and a decrease in the invasive-ness of rat embryos may be important reasons for the failure of interspecific pregnancy between rat and mouse.
