Affiliation:
1. Department of Biochemistry and Molecular Biophysics, Columbia University College of Physicians and Surgeons, New York, NY 10032.
Abstract
The homeotic genes of Drosophila are expressed in overlapping domains along the anterior-to-posterior axis and specify the distinct morphological patterns of each parasegment. Within single parasegments, the levels of homeotic gene expression are often modulated, in part because of cross-regulation by other homeotic gene products. However, the functional significance of different levels of homeotic gene expression is unclear. Here modulations in Ultrabithorax (Ubx) expression within parasegment 6 are examined. Specifically, Ubx is shown to be down-regulated in the posterior compartment of this parasegment by engrailed (en). The significance of Ubx repression by en was demonstrated by characterizing the expression of the Ubx target gene, Distal-less (Dll). In the posterior compartment of parasegment 6, Dll is normally expressed in a small cluster of cells. If Ubx is expressed uniformly via a heat-shock promoter, Dll is inappropriately repressed in these posterior compartment cells. In the anterior compartment of parasegment 6, Dll is normally repressed by high levels of Ubx. However, if en is expressed uniformly via a heat-shock promoter, Ubx is repressed and Dll is derepressed. Because Dll is required for the development of larval sensory structures, these results demonstrate that en-mediated repression of Ubx in the posterior compartment is necessary for the morphology of parasegment 6. Thus, different levels of homeotic gene expression can be important for their segmental patterning functions.
Publisher
The Company of Biologists
Subject
Developmental Biology,Molecular Biology
Cited by
28 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献