Analysis of Drosophila salivary gland, epidermis and CNS development suggests an additional function of brinker in anterior-posterior cell fate specification

Salivary glands are simple structured organs which can serve as a model sys tem in the study of organogenesis. Following a large EMS mutagenesis we hav e identified a number of genes required for normal salivary gland developme nt. Mutations in the locus small salivary glands-1 (ssg-1) lead to a drasti c reduction in the size of the salivary glands. The gene ssg-1 was cloned a nd subsequent sequence and genetic analysis showed identity to the recently published gene brinker. The salivary gland placode in brinker mutants appe ars reduced along both the anterior-posterior and dorso-ventral axis. Analy sis of the brinker cuticle phenotype revealed a similar loss of anterior-po sterior as well as lateral cell fates. The abdominal ventral denticle belts show a reduced number of setae in the first denticle row. Furthermore, we observed a preferential loss of lateral neuroblasts in the anterior paraseg ment. Together, these phenotypes suggest that brinker not only plays a role in dorso-ventral but also in anterior-posterior axis patterning. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.