Identification and developmental expression of three Distal-less homeobox containing genes in the ascidian Ciona intestinalis

Several homeobox-containing genes related to Drosophila Distal-less (Dll) h ave been isolated from a wide variety of organisms and have been shown to f unction as developmental regulators. While in Drosophila only one Dll gene has been described so far, in Vertebrates many components of the Dir multig enic family have been characterized. This suggests that, during the evoluti on of the Chordate phylum, the Dir genes arose from an ancestral Dll/Dlx ge ne via gene duplication. We have previously reported the isolation of two D ll-related homeoboxes from the protochordate Ciona intestinalis, and descri bed their clustered arrangement (Gene 156 (1995) 253). Here we present the detailed genomic organization and spatial-temporal expression of these two genes, Ci-Dll-A and Ci-Dll-B, and describe the isolation and characterizati on of another member of the ascidian family of Dll-related genes, which we tentatively named Ci-Dll-C. (C) 2000 Elsevier Science Ireland Ltd. All righ ts reserved.