A GENETIC-ANALYSIS OF PANNIER, A GENE NECESSARY FOR VIABILITY OF DORSAL TISSUES AND BRISTLE POSITIONING IN DROSOPHILA

A genetic and phenotypic analysis of the gene pannier is described. An imals mutant for strong alleles die as embryos in which the cells of t he amnioserosa are prematurely lost. This leads to a dorsal cuticular hole. The dorsal-most cells of the images are also affected: viable mu tants exhibit a cleft along the dorsal midline. pannier mRNA accumulat es specifically in the dorsal-most regions of the embryo and the imagi nal discs. Viable mutants and mutant combinations also affect the thor acic and head bristle patterns in a complex fashion. Only those bristl es within the area of expression of pannier are affected. A large numb er of alleles have been studied and reveal that pannier may have oppos ing effects on the expression of achaete and scute leading to a loss o r a gain of bristles.