title: YA is needed for proper nuclear organization to transition between meiosis and mitosis in Drosophila.
abstract: BACKGROUND
  The Drosophila YA protein is required to initiate the embryonic cleavage divisions. After egg activation, YA enters nuclei and interacts with chromatin and the nuclear lamina. This study was designed to define more precisely the events prior to the first cleavage division that are dependent upon YA.
  
  
  RESULTS
  We find that meiosis is completed normally in the absence of YA function. The first defects in embryos and eggs from mutant mothers first appear just after the completion of meiosis, and are seen as abnormal associations among the resultant haploid nuclei. These defects are associated with asynchronies in the cell cycle-dependent chromatin condensation state of the haploid nuclei. However, we find evidence of DNA replication in the absence of YA function.
  
  
  CONCLUSIONS
  Our data suggest YA function is needed at a control point, following meiosis II and the initiation of the first postmeiotic S phase, which is sensitive to the chromatin condensation state of the haploid meiotic products.
authors.affiliation: Dept of Molecular Biology and Genetics, Cornell University, Ithaca NY 14853, USA. klb56@cornell.edu
authors.forename: Katharine L
authors.initials: KL
authors.lastname: Sackton
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Lopez
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Berman
authors.forename: Mariana F
authors.initials: MF
authors.lastname: Wolfner
mesh_terms: D000818:Animals; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004330:Drosophila / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D008540:Meiosis / Q000235:genetics / Q000502:physiology*; D008853:Microscopy; D008938:Mitosis / Q000235:genetics / Q000502:physiology*
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C066829:fs(1)Ya protein, Drosophila