title: Modifiers of terminal deficiency-associated position effect variegation in Drosophila.
abstract: Terminal deletions of a Drosophila minichromosome (Dp(1;f)1187) dramatically increase the position effect variegation (PEV) of a yellow(+) body-color gene located in cis. Such terminal deficiency-associated PEV (TDA-PEV) can be suppressed by the presence of a second minichromosome, a phenomenon termed "trans-suppression." We performed a screen for mutations that modify TDA-PEV and trans-suppression. Seventy suppressors and enhancers of TDA-PEV were identified, but no modifiers of trans-suppression were recovered. Secondary analyses of the effects of these mutations on different PEV types identified 10 mutations that modify only TDA-PEV and 6 mutations that modify TDA-PEV and only one other type of PEV. One mutation, a new allele of Su(var)3-9, affects all forms of PEV, including silencing associated with the insertion of a transgene into telomeric regions (TPE). This Su(var)3-9 allele is the first modifier of PEV to affect TPE and provides a unique link between different types of gene silencing in Drosophila. The remaining mutations affected multiple PEV types, indicating that general PEV modifiers impact TDA-PEV. Modifiers of TDA-PEV may identify proteins that play important roles in general heterochromatin biology, including proteins involved in telomere structure and function and the organization of chromosomes in the interphase nucleus.
authors.affiliation: Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA. karpen@salk.edu
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Donaldson
authors.forename: Amy
authors.initials: A
authors.lastname: Lui
authors.forename: Gary H
authors.initials: GH
authors.lastname: Karpen
mesh_terms: D000818:Animals; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins; D017353:Gene Deletion; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D016615:Telomere
chemical_list: D029721:Drosophila Proteins; D019476:Insect Proteins; C050680:y protein, Drosophila