Molecular and Genetic Characterization of a Flight Defective Mutant in Drosophila. L. Morrison , B. Clendening , J. Bacalski , J. Mendy , K. Verdun , G.L. Harris. Dept. Biol & Cell Molecular, San Diego State Univ, San Diego, CA.
We are using enhancer detection analysis to screen for genes which have important roles in adult Drosophila muscle structure and function. AS1 is one such enhancer trap insertion line that expresses the lacZ reporter gene in cells of the indirect flight muscles. The enhancer trap maps to position 46C. We generated a recessive flightless mutant by imprecise excision of the P-lwb element which disrupted a putative gene, fldA. (Morrison et al, 1998)1. Recently, we performed local hop and excision strategies in a mutagenesis screen to acquire additional alleles of fldA. Two local hop and excision lines were obtained which exhibit slight defects in flight behavior. These lines do not complement one another, nor the original flight defective excision line, suggesting disruption of the same gene. Electron photomicrographs from the mutant lines display disruptions of myofibrils similar to those seen in the recessive flightless mutant. A 2.7kb cDNA clone has been obtained from a library screen. A Northern blot probed with the cDNA uncovered a 2.9kb transcript that appears to be unaltered in the mutant lines. A Southern blot probed with the cDNA reveals rearrangements associated with the parental and mutant lines. This cDNA bears no significant homology to known genes and overlaps a Drosophila BAC clone which maps to position 46C-46D. These data suggest that this previously uncharacterized gene may underlie the phenotype we observe in the flightless mutant. We are further characterizing the mutation using 5'RACE and PCR. A developmental Northern analysis will be performed to reveal the expression levels at different stages. We will also use in situ hybridization to visualize the expression pattern of the gene. Ultimately, we hope to rescue the flightless mutant using germ line transformation. (Supported by the Muscular Dystrophy Association). 1 Abstract from the 39th Annual Drosophila Research Conference.