Effects of Plasminogen on Sperm-Oocyte Interaction during In Vitro Fertilization in the Pig
2008
Sa, S.J. (University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, UK) | Kim, T.S. (Kangwon National University, Chuncheon, Republic of Korea) | Park, S.B. (National Institute of Animal Science, RDA, Seonghwan, Republic of Korea) | Lee, D.S. (Kyungpook National University, Daegu, Republic of Korea), E-mail: [email protected] | Park, C.K. (University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, UK), E-mail: [email protected]
Plasminogen activators (PAs) are serine protease that cleave plasminogen to form the active protease plasmin. PA/plasmin system play a role in mammalian fertilization and motility and acrosome reaction of sperm. The present study was undertaken to identify PAs in porcine gametes and investigate a possible role of plasminogen in in vitro fertilization in the pig. When boar spermatozoa were preincubated in a fertilization medium (mTBM) for 0, 2, 4 or 6 h, the activity of tPA-PAI (110~117 kDa), tPA (62~70 kDa), and uPA (34~38 kDa) was observed in the sperm incubation medium and sperm sample. PA activities in the sperm incubation medium significantly (p less than 0.05) increased according to increasing incubation times, while PA activities in sperm significantly (p less than 0.05) decreased at the same times. In addition, the rate of acrosome reaction in spermatozoa increased by increasing culture times. When oocytes were separated from porcine cumulus-oocytes complexes at 0, 22 or 44 h of maturation culture, no PA activities were observed in cumulus free-oocyte just after aspiration from follicles. However, the activity of tPA-PAI (108~113 kDa) and tPA (75~83 kDa) was observed at 22 h of in vitro culture and significantly (p less than 0.05) increased as the duration of the culture increased. On the other hand, when porcine oocytes were activated by sperm penetration or calcium ionophore, plasminogen significantly (p less than 0.05) increased ZP dissolution time (sec) in activated oocytes by sperm penetration. These results suggest that supplementation of plasminogen to fertilization medium may play a positive role in the improvement of in vitro fertilization ability in the pig.
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