A GENETIC DEFICIENCY THAT SPANS THE FLIGHTIN GENE OF DROSOPHILA-MELANOGASTER AFFECTS THE ULTRASTRUCTURE AND FUNCTION OF THE FLIGHT MUSCLES

We have developed a reverse-genetic approach to study the function of flightin, a unique protein of the flight muscle myofibril of Drosophil a melanogaster. We describe the generation and characterization of Df( 3L)fln1, a lethal genetic deficiency in the 76BE region of the third c hromosome which deletes several genes, including the gene for flightin , We show that heterozygous flies harboring the Df(3L)fln1 mutation ex hibit both impaired flight and ultrastructural defects in their flight muscle myofibrils. We found that the mutation does not interfere with assembly of the myofibril but leads to disorganization of peripheral myofilaments in adult myofibrils, Most myofibrils, nevertheless, retai n an intact core that represents approximately 80% of the normal diame ter. Mechanical analysis of single skinned flight muscle fibers demons trates that the mutation has no significant effect on net power output but increases the frequency at which maximum power is delivered to th e wings, potentially reducing the overall performance of the results s uggest that flightin is an of the flight muscle contractile flight sys tem. The indispensable part mechanism.