Abnormalities of ultrastructure and calcium distribution in the flight muscle of a flightless mutant of Drosophila melanogaster.

An X-linked mutant of Drosophila melanogaster was isolated which was completely unable to fly. The map position of the mutation is 43 +/- 0.1. Gynandromorph analysis indicated that the mutation is autonomously expressed in the flight muscle. Fate-map data show that the focus of the mutation lies close to the ventral midline of the blastoderm. Flightlessness appears to be the result of abnormalities of the thoracic musculature, including highly irregular arrangement of the fibrils, lack of the normal striation pattern and abnormal structure of the mitochondria. X-ray microanalysis (EDAX) demonstrates a pronounced difference in the distribution of calcium in mutant and wild-type flight muscle at the fine-structural level. We propose that an abnormal calcium distribution in the mutant may be associated with the ultrastructural abnormalities and ultimately responsible for the flightless phenotype.