The Drosophila UBC9 homologue lesswright mediates the disjunction of homologues in meiosis I.
BACKGROUND
In Saccharomyces cerevisiae and other organisms, the UBC9 (ubiquitin-conjugating 9) protein modifies the function of many different target proteins through covalent attachment of the ubiquitin-like protein SMT-3/SUMO.


RESULTS
Using a second-site suppression screen of a mutation in the nod locus with a variable meiotic phenotype, we have identified mutations in the Drosophila melanogaster UBC9 homologue, encoded by the gene lesswright (lwr). lwr mutations dominantly suppress the nondisjunction and cytological defects of female meiotic mutations that affect spindle formation. The lwr lethal phenotype is rescued by a Drosophila UBC9/lwr transgene.


CONCLUSIONS
We suggest that LWR mediates the dissociation of heterochromatic regions of homologues at the end of meiotic prophase I. Our model proposes that when there is less LWR protein, homologues remain together longer, allowing for more normal spindle formation in mutant backgrounds and therefore more accurate meiotic chromosome segregation.
Department of Biological Sciences, St. John's University, Jamaica, NY 11439, USA.
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Apionishev
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Malhotra
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Raghavachari
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Tanda
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Rasooly
D000483:Alleles; D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics*; D005260:Female; D016153:Genes, Suppressor / Q000235:genetics; D005816:Genetic Complementation Test; D008025:Ligases / Q000235:genetics*; D008297:Male; D008540:Meiosis / Q000235:genetics*; D009630:Nondisjunction, Genetic; D010641:Phenotype; D017354:Point Mutation / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D019076:Transgenes / Q000235:genetics; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9
D044763:Ubiquitin-Conjugating Enzymes; D008025:Ligases; D000098843:Ubiquitin-Conjugating Enzyme UBC9