Studies on the female-sterile phenotype of 1(1)su(f)ts76a, a temperature-sensitive allele of the suppressor of forked mutation in Drosophila melanogaster.

A new allele of the suppressor of forked [su(f)] mutation in Drosophila melanogaster has been found and designated 1(1)su(f)ts76a. It is temperature-sensitive for suppression of forked (f) and has additional temperature-sensitive phenotypes of lethality, female sterility, and abnormal bristle formation at 29 degrees C. It closely resembles two other conditional alleles of su(f), 1(1)su(f)ts67g and 1(1)ts726. Female sterility at 29 degrees C is characterized by both disorganized egg chambers in the ovarioles and also chorion-deficient oocytes. Both of these abnormalities may be the result of premature follicle cell death. The observations on 1(1)su(f)ts76a are consistent with the proposal that the similar allele, 1(1)ts726, is a cell-lethal mutation specifically affecting mitotically active cells.