title: Xenopus oocyte meiosis lacks spindle assembly checkpoint control.
abstract: The spindle assembly checkpoint (SAC) functions as a surveillance mechanism to detect chromosome misalignment and to delay anaphase until the errors are corrected. The SAC is thought to control mitosis and meiosis, including meiosis in mammalian eggs. However, it remains unknown if meiosis in the eggs of nonmammalian vertebrate species is also regulated by SAC. Using a novel karyotyping technique, we demonstrate that complete disruption of spindle microtubules in Xenopus laevis oocytes did not affect the bivalent-to-dyad transition at the time oocytes are undergoing anaphase I. These oocytes also acquired the ability to respond to parthenogenetic activation, which indicates proper metaphase II arrest. Similarly, oocytes exhibiting monopolar spindles, via inhibition of aurora B or Eg5 kinesin, underwent monopolar anaphase on time and without additional intervention. Therefore, the metaphase-to-anaphase transition in frog oocytes is not regulated by SAC.
authors.affiliation: Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario K1H BL6, Canada.
authors.forename: Hua
authors.initials: H
authors.lastname: Shao
authors.forename: Ruizhen
authors.initials: R
authors.lastname: Li
authors.forename: Chunqi
authors.initials: C
authors.lastname: Ma
authors.forename: Eric
authors.initials: E
authors.lastname: Chen
authors.forename: X Johné
authors.initials: XJ
authors.lastname: Liu
mesh_terms: D000705:Anaphase / Q000187:drug effects; D000818:Animals; D064127:Aurora Kinases; D016764:Cell Polarity / Q000187:drug effects; D002875:Chromosomes / Q000187:drug effects / Q000378:metabolism; D019926:Cyclin B / Q000378:metabolism; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D003703:Demecolcine / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D007621:Karyotyping; D059566:M Phase Cell Cycle Checkpoints / Q000187:drug effects; D008540:Meiosis / Q000187:drug effects; D008677:Metaphase / Q000187:drug effects; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D015739:Nocodazole / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D059748:Proteolysis / Q000187:drug effects; D008941:Spindle Apparatus / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D014981:Xenopus; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism
chemical_list: D019926:Cyclin B; C003724:3-tritylthio-L-alanine; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; D020764:cdc42 GTP-Binding Protein; D003545:Cysteine; D015739:Nocodazole; D003703:Demecolcine