Meiotic mutants that cause a polar decrease in recombination on the X chromosome in Caenorhabditis elegans.
Recessive mutations in three autosomal genes, him-1, him-5 and him-8, cause high levels of X chromosome nondisjunction in hermaphrodites of Caenorhabditis elegans, with no comparable effect on autosomal disjunction. Each of the mutants has reduced levels of X chromosome recombination, correlating with the increase in nondisjunction. However, normal or elevated levels of recombination occur at the end of the X chromosome hypothesized to contain the pairing region (the left end), with recombination levels decreasing in regions approaching the right end. Thus, both the number and the distribution of X chromosome exchange events are altered in these mutants. As a result, the genetic map of the X chromosome in the him mutants exhibits a clustering of genes due to reduced recombination, a feature characteristic of the genetic map of the autosomes in non-mutant animals. We hypothesize that these him genes are needed for some processive event that initiates near the left end of the X chromosome.
Broverman
S A
SA
Fred Hutchinson Cancer Research Center, Seattle, Washington 98104.
Meneely
P M
PM
D000483:Alleles; D000818:Animals; D005075:Biological Evolution; D017173:Caenorhabditis elegans / Q000235:genetics*; D003433:Crosses, Genetic; D012734:Disorders of Sex Development / Q000235:genetics; D005808:Genes, Recessive; D005816:Genetic Complementation Test; D008040:Genetic Linkage; D008957:Models, Genetic; D009154:Mutation; D009630:Nondisjunction, Genetic; D011995:Recombination, Genetic; D014960:X Chromosome