Characterization of mutations that enhance position-effect variegation in Drosophila melanogaster

Mol Gen Genet. 1989 Apr;216(2-3):328-33. doi: 10.1007/BF00334372.


Several mutants that enhance the gene inactivation associated with position-effect variegation [E(var) mutants] have been characterized. These include three ethyl methanesulfonate (EMS)-induced lesions and a second chromosome duplication. Each of the EMS mutations maps to a discrete euchromatic site on the third chromosome. One is located within the chromosomal region occupied by a cluster of Su(var) mutations. All four E(var) mutants enhance the inactivation of several different variegators and therefore they appear to influence position-effect variegation generally. However, the enhancement caused by the single site E(var) mutations is less striking than that caused by the duplication or by loss of the Y chromosome. The interaction between the E(var) mutants and selected Su(var) mutations, as well as the effects of extra Y heterochromatin on E(var) expression, have also been investigated. Based on the results of these studies, various hypothetical functions of the E(var)+ products are suggested.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Animals
  • Chromosome Mapping
  • Drosophila melanogaster / genetics*
  • Enhancer Elements, Genetic
  • Female
  • Heterochromatin / genetics
  • Male
  • Mutation
  • Phenotype
  • Pigmentation / genetics
  • Y Chromosome


  • Heterochromatin