A Highlights from MBoC Selection: Mutations in Caenorhabditis elegans him-19 Show Meiotic Defects That Worsen with Age |
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Authors: | Lois Tang Thomas Machacek Yasmine M Mamnun Alexandra Penkner Jiradet Gloggnitzer Christina Wegrostek Robert Konrat Michael F Jantsch Josef Loidl Verena Jantsch |
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Institution: | *Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria; and ;§Department of Biomolecular Structural Chemistry, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria |
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Abstract: | From a screen for meiotic Caenorhabditis elegans mutants based on high incidence of males, we identified a novel gene, him-19, with multiple functions in prophase of meiosis I. Mutant him-19(jf6) animals show a reduction in pairing of homologous chromosomes and subsequent bivalent formation. Consistently, synaptonemal complex formation is spatially restricted and possibly involves nonhomologous chromosomes. Also, foci of the recombination protein RAD-51 occur delayed or cease altogether. Ultimately, mutation of him-19 leads to chromosome missegregation and reduced offspring viability. The observed defects suggest that HIM-19 is important for both homology recognition and formation of meiotic DNA double-strand breaks. It therefore seems to be engaged in an early meiotic event, resembling in this respect the regulator kinase CHK-2. Most astonishingly, him-19(jf6) hermaphrodites display worsening of phenotypes with increasing age, whereas defects are more severe in female than in male meiosis. This finding is consistent with depletion of a him-19-dependent factor during the production of oocytes. Further characterization of him-19 could contribute to our understanding of age-dependent meiotic defects in humans. |
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