Sperm penetration of immature and maturing oocytes does not affect phosphorylation of mitogen-activated protein kinase in pigs.
Pig oocytes cultured in vitro for 0, 25, 33 and 44 h were inseminated by frozen-thawed ejaculated sperm. At specified times after insemination, sperm penetration, cell cycle progression and mitogen-activated protein kinase (MAPK) phosphorylation were evaluated. It was shown that: (1) oocytes at various maturational stages could be penetrated by sperm; (2) sperm penetration did not affect meiotic cell cycle progression; (3) sperm penetration of germinal vesicle (GV) oocytes and maturing oocytes did not alter MAPK phosphorylation; and (4) when premetaphase I (pre-MI) and metaphase I (MI) oocytes, in which MAPK was activated, were fertilised, no evident MAPK dephosphorylation was detected as in metaphase II oocytes. The data suggest that sperm penetration before oocyte maturation does not affect MAPK phosphorylation and that the machinery inactivating MAPK upon fertilisation is not developed in maturing (pre-MI to MI) oocytes.
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, 25 Beisihuan Xilu, Haidian, Beijing, People's Republic of China.
H M
HM
Quan
X Q
XQ
Meng
Y
Y
Hou
Q Y
QY
Sun
D000818:Animals; D002478:Cells, Cultured; D005260:Female; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009865:Oocytes / Q000201:enzymology* / Q000254:growth & development*; D010766:Phosphorylation; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000502:physiology; D013552:Swine
D020928:Mitogen-Activated Protein Kinases