NOTES: Small Differences in Drosophila Tropomyosin Expression Have Significant Effects on Muscle Function

Abstract

The effects of promoter deletions on Drosophila tropomyosin I (TmI) gene expression have been determined by measuring Tml RNA levels in transformed flies. Decreases in RNA levels have been correlated with rescue of flightless and jumpless mutant phenotypes in Ifm(3)3 mutant transformed flies and changes in muscle infrastructure. The results of this analysis have allowed us to identify a region responsible for 20% of maximal TmI expression, estimate threshold levels of TmI RNA required for indirect flight and jump muscle function, and obtain evidence suggesting that sarcomere length may be an important determinant of flight muscle function.