Recombination between small X chromosome duplications and the X chromosome in Caenorhabditis elegans.
Twelve new X chromosome duplications were identified and characterized. Eight are translocated to autosomal sites near four different telomeres, and four are free. Ten include unc-1(+), which in wild type is near the left end of the X chromosome, and two of these, mnDp72(X;IV) and mnDp73(X;f), extend rightward past dpy-3. Both mnDp72 and mnDp73 recombined with the one X chromosome in males in the unc-1-dpy-3 interval at a frequency 15- to 30-fold higher than was observed for X-X recombination in hermaphrodites in the same interval. Recombinant duplications and recombinant X chromosomes were both recovered. Recombination with the X chromosome in the unc-1-dpy-3 interval was also detected for five other unc-1(+) duplications, even though their right breakpoints lie within the interval. In hermaphrodites, mnDp72 and mnDp73 promoted meiotic X nondisjunction and recombined with an X chromosome in the unc-1-dpy-3 interval at frequencies comparable to that found for X-X recombination; mnDp72(X;IV) also promoted trisomy for chromosome IV. A mutation in him-8 IV was identified that severely reduced recombination between the two X chromosomes in hermaphrodites and between mnDp73 and the X chromosome in males. Recombination between the X chromosome and duplications of either the right end of the X or a region near but not including the left end was rare. We suggest that the X chromosome has one or more elements near its left end that promote meiotic chromosome pairing.
Herman
R K
RK
Department of Genetics and Cell Biology, University of Minnesota, St. Paul 55108.
Kari
C K
CK
D000818:Animals; D002107:Caenorhabditis / Q000235:genetics*; D012734:Disorders of Sex Development; D005786:Gene Expression Regulation; D005838:Genotype; D008297:Male; D005810:Multigene Family; D009154:Mutation; D011995:Recombination, Genetic; D013094:Spermatozoa; D013489:Suppression, Genetic; D014314:Trisomy; D014960:X Chromosome