1994 Fiscal Year Final Research Report Summary
Molecular mechanisms involved in the sperm maturation.
| Project/Area Number |
05044121
|
|---|
| Research Category |
Grant-in-Aid for international Scientific Research
|
| Allocation Type | Single-year Grants |
|---|
| Section | Joint Research |
|---|
| Research Institution | University of Tsukuba |
|---|
Principal Investigator |
OKAMURA Naomichi Institute of Basic Medical Sciences, University of Tsukuba, 基礎医学系, 講師 (30134224)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HARRISON RA. AFRC, 動物正理学・遺伝学研究所(英), 主任科学職員
DACHEUX J.L. CNRS, 国立農学研究所(フランス), 主任研究官
NAGAI Takashi Tohoku National Agricultural Experiment Station, 東北農試・家畜繁殖研究室, 室長
HARRISON Robin a.p. Agricultural & Food Research Council (UK)
DACHEUX Jean-louis INRA/CNRS (France)
|
|---|
| Project Period (FY) |
1993 – 1994
|
| Keywords | Sperm Maturation / Epididymis / Glutathione Peroxidase / Calcium / Acrosome Reaction / Capacitation |
|---|
| Research Abstract |
Mammalian sperm acquire the capacity for motility and fertility during transit through epididymis. The epididymis assists sperm maturation to provide sperm with microenvironment successively changing from caput to cauda. The proteins secreted from restricted regions in epididymis seem to be very important for sperm to acquire motility and fertilizing capacity. In this study, we purified a 23kDa protein from porcine cauda epididymal fluid. It was identified as an epididymis-specific glutathione peroxidase by cloning and analyzing its cDNA.The 23kDa protein dose not contain selenocysteine in its catalytic center, resulting in the very low catalytic activity. The mRNA of the 23kDa protein is detected only in the proximal caput epididymis. After being secreted into luminal fluid, the 23kDa protein binds to the surface of the acrosomal region of sperm. Furthermore, it has been also found that the 23kDa protein is released from sperm during acrosome reaction. These results suggest that the 23kDa protein is specifically expressed in the proximal caput epididymis, secreted into the lumen and then binds to the surface of maturating sperm. This protein may be involved in the regulation of the acrosome reaction.
In porcine sperm, relatively high levels of calcium are required for the induction of capacitation and subsequent acrosome reaction and for successful fertilization. It is likely that the procedures stimulating Ca^<2+> entry into sperm improve the result of the attempts for fertilization of porcine eggs in vitro. In the present study, forskolin and casein phosphopeotide have been shown to increase the intracellular Ca^<2+> levels in sperm. So, they can be used as an exogenous promotor in the attempt at in vitro fertilization by enhancing the acrosome reaction.
|
