ORAL PRESENTATION Regulation of MPF activity in fertilized maturing mouse oocytes

MPF (M-phase promoting factor) is an essential regulator of meiotic division in oocytes. It consists of catalytic subunit CDK1 / p34cdc2 (cyclin-dependent ki-nase1) and regulatory subunit – cyclin B. During meiotic maturation of the mouse oocyte MPF activity increases, as oocytes progress towards metaphase of the first meiotic division (metaphase I). Next MPF activity is reduced at metaphase I/anaphaseI transi-tion and rises again in the metaphase of the second meiotic division (metaphase II) (Verlhac et al., 1994). After fertilization of metaphase II oocyte, MPF activity is diminished in process involving calcium-dependent proteolysis of cyclin B (Nixon et al., 2002; Verlhac et al., 1994). Spermatozoa introduced into maturing oocytes trig