title: Bovine immature oocytes acquire developmental competence during meiotic arrest in vitro.
abstract: To test the hypothesis that oocytes require time to acquire developmental competence during meiotic arrest, we investigated the effects of butyrolactone I (BL I), a potent and specific inhibitor of cyclin-dependent kinase, on the developmental competence of bovine oocytes after in vitro fertilization (IVF) following release from meiotic arrest. In the present study, 4 culture conditions were used: addition of BSA or fetal bovine serum (FBS) under 2 oxygen tensions (5% vs. 20%) during meiotic arrest with 100-microM BL I. The developmental competence to the blastocyst stage was higher (P < 0.01) in oocytes that were arrested in FBS-supplemented medium under 5% O2 (37%) than in oocytes that were arrested under other conditions (5%-24%) or that matured directly following follicle aspiration (23%). The time course of nuclear maturation of BL I-treated oocytes was also examined. The results demonstrated that oocytes treated with BL I start germinal vesicle (GV) breakdown and reach the metaphase II stage 5.5-6.0 h earlier than nonarrested oocytes. The developmental rates to the blastocyst stage of BL I-treated oocytes matured for 15.5 and 21 h were higher (P < 0.05) than those of nontreated oocytes matured for 21 and 26.5 h, respectively. These results demonstrate that bovine immature oocytes, which were arrested at the GV stage with BL I in FBS-supplemented medium under low oxygen tension, acquire higher developmental competence during meiotic arrest.
authors.affiliation: Embryo Transplantation Laboratory, Snow Brand Milk Products Co. Ltd., 119 Uenae, Tomakomai, Hokkaido 059-1365, Japan.
authors.forename: Shu
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Naojiro
authors.initials: N
authors.lastname: Minami
authors.forename: Ryo
authors.initials: R
authors.lastname: Takakura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Imai
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001755:Blastocyst / Q000502:physiology; D002417:Cattle / Q000502:physiology*; D002467:Cell Nucleus / Q000502:physiology; D002478:Cells, Cultured; D003470:Culture Media; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D005312:Fetal Blood; D007700:Kinetics; D008540:Meiosis / Q000187:drug effects; D009865:Oocytes / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D010100:Oxygen / Q000008:administration & dosage; D012710:Serum Albumin, Bovine; D020858:Tissue and Organ Harvesting
chemical_list: D003470:Culture Media; D012710:Serum Albumin, Bovine; C082868:butyrolactone I; D015107:4-Butyrolactone; D010100:Oxygen