title: A Caenorhabditis elegans cohesion protein with functions in meiotic chromosome pairing and disjunction.
abstract: We have studied four Caenorhabditis elegans homologs of the Rad21/Scc1/Rec8 sister-chromatid cohesion protein family. Based on the RNAi phenotype and protein localization, it is concluded that one of them, W02A2.6p, is the likely worm ortholog of yeast Rec8p. The depletion of C. elegans W02A2.6p (called REC-8) by RNAi, induced univalent formation and splitting of chromosomes into sister chromatids at diakinesis. Chromosome synapsis at pachytene was defective, but primary homology recognition seemed unaffected, as a closer-than-random association of homologous fluorescence in situ hybridization (FISH) signals at leptotene/zygotene was observed. Depletion of REC-8 also induced chromosome fragmentation at diakinesis. We interpret these fragments as products of unrepaired meiotic double-stranded DNA breaks (DSBs), because fragmentation was suppressed in a spo-11 background. Thus, REC-8 seems to be required for successful repair of DSBs. The occurrence of DSBs in REC-8-depleted meiocytes suggests that DSB formation does not depend on homologous synapsis. Anti-REC-8 immunostaining decorated synaptonemal complexes (SCs) at pachytene and chromosomal axes in bivalents and univalents at diakinesis. Between metaphase I and metaphase II, REC-8 is partially lost from the chromosomes. The partial loss of REC-8 from chromosomes between metaphase I and metaphase II suggests that worm REC-8 might function similarly to yeast Rec8p. The loss of yeast Rec8p from chromosome arms at meiosis I and centromeres at meiosis II coordinates the disjunction of homologs and sister chromatids at the two meiotic divisions.
authors.affiliation: Department of Cytology and Genetics, Institute of Botany, University of Vienna, A-1030 Vienna, Austria.
authors.forename: P
authors.initials: P
authors.lastname: Pasierbek
authors.forename: M
authors.initials: M
authors.lastname: Jantsch
authors.forename: M
authors.initials: M
authors.lastname: Melcher
authors.forename: A
authors.initials: A
authors.lastname: Schleiffer
authors.forename: D
authors.initials: D
authors.lastname: Schweizer
authors.forename: J
authors.initials: J
authors.lastname: Loidl
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000235:genetics; D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D002842:Chromatids / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone; D020090:Chromosome Segregation / Q000235:genetics*; D017124:Conserved Sequence; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000235:genetics*; D015801:Helminth Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D008540:Meiosis / Q000235:genetics*; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D010750:Phosphoproteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D013573:Synaptonemal Complex / Q000235:genetics / Q000378:metabolism; D000097722:Cohesins
chemical_list: D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D005656:Fungal Proteins; D015801:Helminth Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C490529:MCD1 protein, S cerevisiae; C490530:scc-1 protein, C elegans; C077081:REC8 protein, S pombe; D000097722:Cohesins