Comparison of DNA methylation levels of repetitive loci during bovine development

<p> Abstract</p> <p>Background</p> <p>DNA methylation of cytosine residues in CpG dinucleotide controls gene expression and dramatically changes during development. Its pattern is disrupted in cloned animals suggesting incomplete reprogramming during somatic cell nuclear transfer (the first reprogramming). However, the second reprogramming occurs in the germ cells and epigenetic errors in somatic cells of cloned animals should be erased. To analyze the DNA methylation changes on the spermatogenesis of bulls, we measured DNA methylation levels of three repetitive elements in blastocysts, blood and sperm.</p> <p>Methods</p> <p>DNA from PBLs (peripheral blood leukocytes), sperm and individual IVF (<it>in vitro</it> fertilized) and parthenogenetic blastocysts was isolated and bisulfite converted. Three repetitive elements; Satellite I, Satellite II and <it>art2</it> sequences were amplified by PCR with specific pairs of primers. The PCR product was then cut by restriction enzymes and analyzed by agarose gel electrophoresis for determining the DNA methylation levels.</p> <p>Results</p> <p>Both Satellite I and Satellite II sequences were highly methylated in PBLs, whereas hypo-methylated in sperm and blastocysts. The <it>art2</it> sequence was half methylated both in PBLs and sperm but less methylated in blastocysts. There was no difference in DNA methylation levels between IVF and parthenogenetic blastocysts.</p> <p>Conclusions</p> <p>These results suggest that there is a dynamic change of DNA methylation during embryonic development and spermatogenesis in cattle. Satellite I and Satellite II regions are methylated during embryogenesis and then de-methylated during spermatogenesis. However, <it>art2</it> sequences are not de-methylated during spermatogenesis, suggesting that this region is not reprogrammed during germ cell development. These results show dynamic changes of DNA methylation levels during bovine embryogenesis, especially genome-wide reprogramming in germ cells.</p

Affinity-based screening of MDM2/MDMX-p53 interaction inhibitors by chemical array: Identification of novel peptidic inhibitors.

MDM2 and MDMX are oncoproteins that negatively regulate the activity and stability of the tumor suppressor protein p53. The inhibitors of protein-protein interactions (PPIs) of MDM2-p53 and MDMX-p53 represent potential anticancer agents. In this study, a novel approach for identifying MDM2-p53 and MDMX-p53 PPI inhibitor candidates by affinity-based screening using a chemical array has been established. A number of compounds from an in-house compound library, which were immobilized onto a chemical array, were screened for interaction with fluorescence-labeled MDM2 and MDMX proteins. The subsequent fluorescent polarization assay identified several compounds that inhibited MDM2-p53 and MDMX-p53 interactions

Design and synthesis of fluorescent probes for GPR54.

Kisspeptins are neuropeptides that induce the secretion of gonadotropin-releasing hormone via the activation of the cognate receptor, G-protein coupled receptor 54 (GPR54). The kisspeptin-GPR54 axis is associated with the onset of puberty and the maintenance of the reproductive system. In this study, several fluorescent probes have been designed and synthesized for rat GPR54 through the modification of the N-terminus of rat kisspeptins to allow for the visualization of the expression and localization of kisspeptin receptor(s) in living cells and native tissues. The tetramethylrhodamine (TMR) and rhodamine green (RG)-labeled kisspeptins exhibited good binding and agonistic activities towards GPR54, and the results of the application studies demonstrated that these fluorescent probes could be used effectively for the detection of GPR54 receptors in flow cytometry and confocal microscopy experiments

False-negative coagulation factor activity results due to the presence of antiphospholipid antibodies in a case of autoimmune hemolytic anemia

An 88-year-old female was admitted with autoimmune hemolytic anemia (AIHA). Coagulation test revealed severe prolongation of activated partial thromboplastin time (APTT). APTT cross-mixing test with patient plasma and normal plasma demonstrated an inhibitory pattern. Several intrinsic coagulation factor activities, particularly factor IX, showed remarkable decreases, and the inhibitor titers for coagulation factors VIII and IX were elevated. Although AIHA with existing antiphospholipid (aPL) antibodies was diagnosed initially, purpura developed on extremities intermittently during the clinical course. Considering the possibility of coexisting acquired hemophilia, APTT cross-mixing test with patient’s plasma and equal amount of the recombinant factor VIII product instead of normal plasma was performed. The APTT value on equal mixing samples with patient plasma and recombinant factor VIII product was decreased to within the normal range, and coagulation factor IX activity was restored. These results indicate that the recombinant factor VIII product had a neutralizing effect on aPL antibodies. We concluded that recombinant factor VIII product may lead to the repair of incorrect results from the APTT-dependent diagnostic system in the presence of aPL antibodies

Functional 1,3a,6a-triazapentalene scaffold : Design of fluorescent probes for kinesin spindle protein (KSP)

1,3a,6a-Triazapentalene is a compact fluorescent chromophore. In this study, triazapentalene was used to modify a series of biphenyl-type inhibitors of kinesin spindle protein (KSP) to develop fluorescent probes for the intracellular visualization of this protein. Microscopic studies demonstrated that these novel triazapentalene-labeled compounds exhibited inhibitory activity towards KSP in cultured cells and provided important information concerning the intracellular distribution

Low susceptibility to N-ethyl-N-nitrosourea-induced transplacental carcinogenesis in Long-Evans Cinnamon (LEC) rats

The Long-Evans Cinnamon (LEC) rat, an animal model of Wilson’s disease, is resistant to a variety of chemical carcinogenesis except liver and colon. In the present study, N-ethyl-N-nitrosourea (ENU)-induced transplacental carcinogenesis was examined in male and female LEC, Long-Evans Agouti (LEA), a sibling line of the LEC rat, and F344 rats (n=21). ENU was administered to pregnant rats as a single s.c. injection at a dose of 60 mg/kg body weight on the 17th day after conception. Cerebral/spinal gliomas and trigeminal/spinal nerve schwannomas developed in both LEA and F344 rats at 30 weeks of age, but no nervous system tumors developed in LEC rats, the difference being statistically significant. Lung adenomas also developed in LEA and F344 rats, but not in LEC rats. Semiquantitative RT-PCR demonstrated that metallothionein (MT)1a, MT2 and O6-methylguanine-DNA methyltransferase (MGMT) mRNA levels in the liver of LEC rats were higher than those in F344 and LEA rats. In addition, Western blot analysis showed that MT (MT1 plus MT2) in the liver of LEC rats was also higher than that in other strains. Present results suggest that high levels of MT and/or MGMT contribute to the resistance to nitrosamine-induced carcinogenesis in LEC rats

Prevention of lethal hepatic injury in Long-Evans Cinnamon (LEC) rats by D-galactosamine hydrochloride

Repeated injections of D-galactosamine hydrochloride (GalN) increase the survival rate of Long-Evans Cinnamon (LEC) rats, an animal model of Wilson’s disease. The aim of the present study was to investigate the mechanism of GalN for prevention of spontaneous lethal hepatic injury in LEC rats. MaleLEC rats were given a single subcutaneous injection of 300mg/kg of GalN or vehicle (0.9%NaCl) at 14weeks, and killed at 28 weeks of age. Next, 6-week-old male LEC rats were given weekly subcutaneous injections of 300 mg/kg of GalN or vehicle for 3 or 12 weeks, and their hepatic 8-hydroxydeoxy-2’-guanosine (8-OHdG), glutathione peroxidase (GPX), and catalase activities were measured. None of GalN-treated rats died of hepatic injury (0/12), whereas the mortality rate of control rats given 0.9% NaCl was 17% (2/12). GalN administration for 12 weeks decreased the hepatic 8-OHdG, and GalN administration for either 3 or 12weeks increased the glutathione peroxidase activity. GalN administration increased the serum level of alanine aminotransferase, and accelerated megalocytic degeneration of the hepatocytes. GalN treatment is effective in preventing lethal hepatitis in LEC rats and decrease of oxidative DNA damage by GalN plays an important role in increase of the survival rate