GENETIC-ANALYSIS OF THE DROSOPHILA SINGLE-MINDED GENE REVEALS A CENTRAL-NERVOUS-SYSTEM INFLUENCE ON MUSCLE DEVELOPMENT

The Drosophila single-minded gene is expressed in the embryonic centra l nervous system midline cells and plays a critical role in central ne rvous system development. Additional expression of single-minded is fo und in a subset of ventral muscle precursor cells. Null mutations of s ingle-minded result in an alteration of the ventral oblique muscles, s uch that muscle fibers form inside the embryo above the central nervou s system. This defect is due to the mislocalization of a subset of mes odermal precursor cells. The muscle defect observed in single-minded n ull mutations is not due to the absence of single-minded expression in muscle precursor cells and likely results from an influence of the ce ntral nervous system on ventral muscle development.