title: Crossover distribution and frequency are regulated by him-5 in Caenorhabditis elegans.
abstract: Mutations in the him-5 gene in Caenorhabditis elegans strongly reduce the frequency of crossovers on the X chromosome, with lesser effects on the autosomes. him-5 mutants also show a change in crossover distribution on both the X and autosomes. These phenotypes are accompanied by a delayed entry into pachytene and premature desynapsis of the X chromosome. The nondisjunction, progression defects and desynapsis can be rescued by an exogenous source of double strand breaks (DSBs), indicating that the role of HIM-5 is to promote the formation of meiotic DSBs. Molecular cloning of the gene shows that the inferred HIM-5 product is a highly basic protein of 252 amino acids with no clear orthologs in other species, including other Caenorhabditis species. Although him-5 mutants are defective in segregation of the X chromosome, HIM-5 protein localizes preferentially to the autosomes. The mutant phenotypes and localization of him-5 are similar but not identical to the results seen with xnd-1, although unlike xnd-1, him-5 has no apparent effect on the acetylation of histone H2A on lysine 5 (H2AacK5). The localization of HIM-5 to the autosomes depends on the activities of both xnd-1 and him-17 allowing us to begin to establish pathways for the control of crossover distribution and frequency.
authors.affiliation: Department of Biology, Haverford College, Haverford, Pennsylvania 19041, USA.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Meneely
authors.forename: Olivia L
authors.initials: OL
authors.lastname: McGovern
authors.forename: Frazer I
authors.initials: FI
authors.lastname: Heinis
authors.forename: Judith L
authors.initials: JL
authors.lastname: Yanowitz
mesh_terms: D000107:Acetylation; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D020090:Chromosome Segregation; D003001:Cloning, Molecular; D003434:Crossing Over, Genetic; D053903:DNA Breaks, Double-Stranded; D005786:Gene Expression Regulation; D017238:Genes, Helminth; D057850:Hermaphroditic Organisms / Q000235:genetics / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D008239:Lysine / Q000235:genetics / Q000378:metabolism; D008297:Male; D049471:Pachytene Stage; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D021381:Protein Transport; D034622:RNA Interference; D051135:Rad51 Recombinase / Q000378:metabolism; D013045:Species Specificity; D014960:X Chromosome / Q000235:genetics*
chemical_list: D029742:Caenorhabditis elegans Proteins; D002843:Chromatin; D006657:Histones; C553799:xnd-1 protein, C elegans; D051135:Rad51 Recombinase; C495148:rad-51 protein, C elegans; D008239:Lysine