Isolation of dominant XO-feminizing mutations in Caenorhabditis elegans: new regulatory tra alleles and an X chromosome duplication with implications for primary sex determination.
A strain of Caenorhabditis elegans was constructed that permits selection of dominant or sex-linked mutations that transform XO animals (normally male) into fertile females, using a feminizing mutation, tra-2(e2046gf), which by itself does not sexually transform XO males. Twenty-three mutations were isolated after chemical mutagenesis and found to fall into both expected classes (four dominant tra-1 mutations and eight recessive xol-1 mutations) and novel classes. The novel mutations include 10 second-site mutations of tra-2, which are called eg mutations, for enhanced gain-of-function. The tra-2(gf, eg) alleles lead to complete dominant transformation of XO animals from fertile male into fertile female. Also isolated was a duplication of the left end of the X chromosome, eDp26, which has dominant XO lethal and feminizing properties, unlike all previously isolated duplications of the X chromosome. The properties of eDp26 indicate that it carries copies of one or more numerator elements, which act as part of the primary sex-determination signal, the X:A ratio. The eDp26 duplication is attached to the left tip of the X chromosome in inverted orientation and consequently can be used to generate unstable attached-X chromosomes.
Hodgkin
J
J
Medical Research Council Laboratory of Molecular Biology, Cambridge, England.
Albertson
D G
DG
D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000502:physiology; D002874:Chromosome Mapping; D005260:Female; D005298:Fertility; D005799:Genes, Dominant; D017238:Genes, Helminth; D005804:Genes, Lethal; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D009154:Mutation; D012733:Sex Differentiation / Q000235:genetics*; D014960:X Chromosome