Characterization of mutations that enhance position-effect variegation in Drosophila melanogaster.
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.
Sinclair
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DA
Department of Zoology, University of British Columbia, Vancouver, Canada.
Lloyd
V K
VK
Grigliatti
T A
TA
D000483:Alleles; D000818:Animals; D002874:Chromosome Mapping; D004331:Drosophila melanogaster / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D005260:Female; D006570:Heterochromatin / Q000235:genetics; D008297:Male; D009154:Mutation; D010641:Phenotype; D010858:Pigmentation / Q000235:genetics; D014998:Y Chromosome
D006570:Heterochromatin