Inhibition by dibutyryl cyclic AMP of the transition to metaphase of mouse oocyte nuclei and its reversal by cell fusion to metaphase oocytes.
Mouse oocytes at metaphase I of meiotic maturation were treated with puromycin, which caused the condensed chromosomes to become decondensed to form an interphase nucleus. The chromosomes returned to a metaphase state 6.3 hr after the oocytes were transferred to puromycin-free medium [H. J. Clarke and Y. Masui (1983) Dev. Biol. 97, 291-301]. In contrast, the chromosomes of the puromycin-treated oocytes remained decondensed within the nucleus if dibutyryl cyclic AMP (dbcAMP) was included in the puromycin-free medium. This implies that dbcAMP inhibited the development of conditions in the oocytes that were required for the transition to metaphase. The chromosomes of puromycin-treated oocytes that were incubated for 7.5 hr in dbcAMP-containing medium returned to metaphase just 1.9 hr after transfer to dbcAMP-free medium. Therefore, the protein synthesis-dependent process that is required for the transition to metaphase could occur in the presence of dbcAMP. Fusion to metaphase II oocytes, or to puromycin-treated oocytes that had returned to metaphase, rapidly induced transition of the nuclei of dbcAMP-inhibited oocytes to metaphase, despite the presence of the inhibitor. These results suggest that the transition of nuclei to metaphase can be induced by a cytoplasmic factor that is present in metaphase oocytes, and that dbcAMP inhibits the development of this factor.
Clarke
H J
HJ
Masui
Y
Y
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology*; D002459:Cell Fusion; D002875:Chromosomes / Q000032:analysis; D005260:Female; D008677:Metaphase / Q000187:drug effects*; D051379:Mice; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects; D011092:Polyethylene Glycols / Q000494:pharmacology; D011691:Puromycin / Q000494:pharmacology
D011092:Polyethylene Glycols; D011691:Puromycin; D003994:Bucladesine