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ABSTRACT. Causes of bovine abortion were surveyed in Korea within a designated period from the cases submitted to the Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University. One hundred and eighty aborted fetuses and mat ernal sera were evaluated by necropsy, histopathology, bacteriology, virology, PCR, and serologic tests. The causes of abortion were identified in 108 (60%) cases, of which 38 (21.1%) were due to the infection with Neospora caninum. None of the 38 cases showed any co-infection with either virus or bacteria. Viral and bacterial causes were diagnosed in 28 (15.5%) and 13 (7.2%) aborted fetuses, respectively. Non-infectious causes such as multiple pregnancy, maternal weakness or torsion of umbilical cord were observed in 22 (12.3%) cases.Results of the present study suggest that N. caninum is believed to be the leading cause of bovine abortion in Korea. Thus, more attention should be paid to this emerging disease in Korea. However, the causes of many aborted fetuses remain undiagnosed in this study. Therefore, this enigma should be clarified through further studies such as chromosomal analysis.

In mammalian species, melatonin is a multi-functional pineal gland hormone that regulates several circadian and seasonal rhythms including reproduction. However, the melatonin study was not common as to the oocytes in the pig. Recently, we reported that exogenous melatonin has beneficial effects on nuclear and cytoplasmic maturation during porcine oocyte IVM and we also reported an existence of melatonin receptor on the cumulus cells and granulose cells (Kang JT et al. 2009 J. Pineal Res. 46(1), 22-28). In this study, as adding further experiments rather than our previous study, we investigated effect of exogeneous melatonin (10 ng mL-1) on the porcine oocytes and analyzed possible factors which can be responsible for that results. Oocytes were recovered by aspiration of slaughterhouse ovaries, and then matured in TCM-199 supplemented with EGF, insulin, pyruvate, cystine, and gonadotropin. Expression of apoptosis-related genes mRNA in oocytes cultured with melatonin were evaluated by real-time PCR (Exp 1), cumulus cell expansion on COC was assessed on the microscopes during in vitro maturation (Exp 2), and developmental effects between melatonin treatement group and non-treatment group on the in vitro culture of parthenogenetically activated oocytes was investigated (Exp 3). In results, oocytes matured with melatonin were assessed for the expression of apoptosis-related genes Bcl-xl (anti-apoptotic gene) and Bax (proapoptotic gene) by real-time quantitative PCR. Analysis of data showed that the expression of Bcl-xl was higher compared to the control while the expression of Bax was decreased relative to the control (P < 0.05). Cumulus cell expansion was evaluated under a stereomicroscope at 22 h, 44 h during IVM. Representative photomicrographs of porcine COC at the start of the IVM, after 22 h and 44 h treatment with melatonin, are shown in Figure. After 22 h of melatonin treatment, cumulus cells were visually expanded compared with non-treatment group. We analyzed significantly greater proportion of parthenogenetically activated oocytes developed to blastocyst when the IVM medium was supplemented with melatonin. Melatonin treatment in the IVM has consequently beneficial effect on the blastocyst formation rates on the development of porcine parthenogenetic embryos (15.4%) compared to non-treatment group (10.7%, P < 0.05). However, cleavage frequency was not affectedby the treatment. In conclusion, the present study demonstrated that melatonin had a beneficial effect on the development of parthenogenetically activated porcine embryos, probably through decreased apoptosis rate and increased cumulus cell expansion. This study was supported by Korean MKE, MEST (BK21 program), and Hanhwa L&C

In vitro studies on mammalian oocytes have shown that follicular fluid-meiosis activating sterol (FF-MAS) can overcome the inhibitory effect of hypoxanthine (Hx) on the resumption of meiosis. FF-MAS, an intermediate in the cholesterol biosynthesis pathway, is converted to testis meiosis–activating sterol by a sterol Δ14-reductase. AY9944 A-7, an inhibitor of Δ14-reductase and Δ7-reductase, induces accumulation of FF-MAS by inhibiting its metabolism. The aim of this study was to evaluate the effects of AY9944 A-7 on meiotic resumption of porcine oocytes, cumulus cell expansion, and gene expression related to M-phase-promoting factor (MPF), mitogen-activated protein kinase (MAPK), and oocyte maturation in oocytes and related to cumulus expansion in cumulus cells. In experiment 1, 1136 cumulus-oocyte complexes (COCs) were cultured in IVM media with 4 different concentrations (0, 10, 20, and 40 μM) of AY9944 A-7 in addition to a meiotic inhibitor (Hx, 4 mM) for 44 h. Oocytes treated with 10 and 20 μM AY9944 A-7 in the presence of Hx had significantly higher GVBD and M2 rates than the control group. However, 40 μM AY9944 A-7 significantly decreased GVBD and M2 rates and increased degeneration of oocytes compared with other groups. In experiment 2, 600 COCs were cultured in IVM media with 4 different concentrations (0, 10, 20, and 40 μM) of AY9944 A-7 in the absence of Hx for 44 h. Cumulus expansion of 40 μM AY9944 A-7 treated group was significantly decreased compared with other groups. In experiment 3, we evaluate the effects of AY9944 A-7 on gene expression, and the experiment was replicated four times. Data on gene expression were analysed using Student’s t-test. Oocytes treated with 10 μM AY9944 A-7 increased expression of genes involved in MPF (Cyclin B and Cdc2), MAPK (C-mos), and oocyte maturation (GDF9 and BMP15). Cumulus cells treated with 10 μM AY9944 A-7 decreased cumulus expansion-related genes (Has2, Tnfaip6, Ptgs2, and Ptx-3). In conclusion, our results suggest that although 10 μM AY9944 A-7 decreased cumulus expansion-related genes, there was no difference in cumulus expansion and it induced meiotic resumption of porcine oocytes with increased MPF, MAPK, and oocyte maturation-related genes. Further studies are needed to evaluate the effect of AY9944 A-7 on porcine embryo development. This study was supported by Ministry Of Trade, Industry & Energy (#10048948), Korea IPET (#114059–3), Research Institute for Veterinary Science, TS Corporation, and the BK21 plus program.