Modifiers of terminal deficiency-associated position effect variegation in Drosophila.
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.
Donaldson
Kathryn M
KM
Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA. karpen@salk.edu
Lui
Amy
A
Karpen
Gary H
GH
D000818:Animals; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins; D017353:Gene Deletion; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D016615:Telomere
D029721:Drosophila Proteins; D019476:Insect Proteins; C050680:y protein, Drosophila