Molecular and General Genetics MGG

, Volume 202, Issue 2, pp 212–218 | Cite as

An X-autosome fusion chromosome of Caenorhabditis elegans

  • D. Christine Sigurdson
  • Robert K. Herman
  • Cynthia A. Horton
  • Claire K. Kari
  • Steven E. Pratt
Article

Summary

The translocation mnT12(IV;X) is a fusion of holocentric chromosomes IV and X, the breakpoints occurring near the left end of IV and the right end of X. Animals homozygous for mnT12 are viable and fertile; they contain five pairs of chromosomes rather than the normal set of six pairs. The mnT12 chromosome is larger than all wild-type chromosomes and thus identifies linkage groups IV and X cytologically. Hermaphrodites heterozygous for mnT12 show high frequency meiotic nondisjunction both between mnT12 and the X chromosome, which results in a high incidence of male self progeny (27% compared to the wild-type incidence of 0.2%), and between mnT12 and chromosome IV, which results in a high incidence of self progeny essentially trisomic for chromosome IV (karyotype IV/mnT12/mnT12). The viability of chromosome IV trisomics has been confirmed by constructing animals trisomic for only normal copies of chromosome IV; these animals are morphologically wild type. Meiotic chromosome disjunction in mnT12 homozygotes appears to be normal, although the frequency of recombination between markers that are normally X-linked is significantly reduced. Males of genotype IV/mnT12/0 are fertile. They can be thought of as having a neo-X(mnT12) neo-Y(normal IV) karyotype since it is possible to maintain a male-hermaphrodite stock of C. elegans consisting of such males and hermaphrodites carrying two neo-X chromosomes and no neo-Y; the organism is thus converted from an XO:XX type of sex determination to an XX:XX system.

Key words

Nematode Nondisjunction Translocation Trisomy 

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Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • D. Christine Sigurdson
    • 1
  • Robert K. Herman
    • 1
  • Cynthia A. Horton
    • 1
  • Claire K. Kari
    • 1
  • Steven E. Pratt
    • 1
  1. 1.Department of Genetics and Cell BiologyUniversity of MinnesotaSt. PaulUSA

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