title: Bovine oocyte and embryo development following meiotic inhibition with butyrolactone I.
abstract: In this study we have shown that butyrolactone I (BL-I), a potent inhibitor of cyclin-dependent kinases, inhibits meiotic resumption in bovine oocytes by blocking germinal vesicle breakdown in a dose-dependent manner. A concentration 100 microM blocked over 60% of oocytes, while 150 microM inhibited almost all oocytes compared to the control in which over 80% resumed meiosis. Following a second 24 hr culture under conditions permissive to normal maturation, almost all (95%) of blocked oocytes resumed meiosis and progressed to metaphase II. In terms of developmental competence, oocytes maintained in meiotic arrest for 24 hr with 100 microM exhibited a similar capacity to develop to the blastocyst stage as nonblocked control oocytes following maturation, fertilization, and culture in vitro. Cryopreservation was employed as a tool to detect differences in the oocyte viability between blocked and control oocytes. Cleavage of oocytes was significantly reduced following vitrification and activation both in BL-I treated (40.2% vs. 71.9%, P < 0.05) and the control groups (45.6% vs. 81.7%, P < 0.05). However, BL-I treated oocytes were less likely to develop into blastocysts following vitrification (20.0% from vitrified vs 42.5% from nonvitrified cleaved oocytes, P < 0.05, based on cleaved oocytes) compared to nontreated oocytes (34.0% from vitrified vs. 42. 9% from nonvitrified oocytes, P < 0.05). These results demonstrate the feasibility of maintaining bovine oocytes in artificial meiotic arrest without compromising their subsequent developmental competence and may represent a tool for improving the development of less competent oocytes.
authors.affiliation: Department of Animal Science and Production, University College Dublin, Lyons Research Farm, Newcastle, County Dublin, Ireland. lonergan@pop3.ucd.ie
authors.forename: P
authors.initials: P
authors.lastname: Lonergan
authors.forename: A
authors.initials: A
authors.lastname: Dinnyes
authors.forename: T
authors.initials: T
authors.lastname: Fair
authors.forename: X
authors.initials: X
authors.lastname: Yang
authors.forename: M
authors.initials: M
authors.lastname: Boland
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D005314:Embryonic and Fetal Development / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008540:Meiosis / Q000187:drug effects*; D009865:Oocytes / Q000187:drug effects* / Q000254:growth & development*
chemical_list: D004791:Enzyme Inhibitors; C082868:butyrolactone I; D018844:Cyclin-Dependent Kinases; D015107:4-Butyrolactone