chersko/Df(3R)Exel6176 transheterozygotes cannot sustain flight, since high frequency wing beat is only sustained for a few seconds, as compared to wild-type and chersko heterozygous controls. These mutants exhibit a moderate but significant decrease in the number of recognizable sarcomeres in adult indirect flight muscles, associated with smaller or fractured Z-discs and actin incorporation into the H-zone, as compared to wild-type and chersko heterozygous controls.
chersko homozygotes do not exhibit abnormal actin accumulation at the H-zone of adult indirect flight muscle sarcomeres.
Mutant egg chambers contain tiny ring canals.
Homozygous females do not lay eggs. Their ovaries show an apparent arrest in oocyte growth at stage 10b and no mature egg chambers are seen. Egg chambers show several defects in cellular morphology and membrane integrity, although they contain the wild-type number of 16 germline cells (15 nurse cells and 1 oocyte). There is a disruption in the normal spatial organisation of germline nuclei in homozygous egg chambers, and in late stages, entire nurse cells and/or nurse cell nuclei are sometimes seen to protrude into the posterior compartment which is normally occupied only by the growing oocyte. Follicle cells do migrate to form a columnar epithelium surrounding the oocyte, but they are frequently more elongated than in wild-type egg chambers. The subsequent centripetal movement of follicle cells along the anterior margin of the oocyte is also abnormal in many egg chambers. Early stage egg chambers have an abnormal organisation of actin filaments in both the ring canals and the subcortical network. The ring canals are absent in stage 10 egg chambers and the radial arrays of actin filaments that extend between the nurse cell membranes and nuclei are disrupted. The nurse cells have abnormal morphology. Breaks or disruptions in the plasma membranes that separate adjacent nurse cell cytoplasms are seen in stage 5 or 6 egg chambers. This allows the cytoplasm of adjacent cells to merge in these regions. The plasma membrane is vesiculated at the break points. The ring canal is frequently incomplete and is morphologically abnormal. chersko/cher1 females are sterile and have defects in ring canal assembly and egg chamber morphology.