cDNA cloning of a quail homeobox gene and its expression in neural crest-derived mesenchyme and lateral plate mesoderm.

We report here the cloning of a quail cDNA related to the Drosophila gene msh and to the mouse genes Hox-7 and Hox-7.1. For this reason we called this cDNA Quox-7. The amino acid homology of Quox-7 cDNA with the above mentioned genes is high (83%) for the homeobox and its 5'- and 3'-flanking sequences, and the homology is medium (43%) for another stretch of amino acids upstream of the homeobox; elsewhere the sequences of quail and mouse cDNAs have diverged significantly. In quail embryos of day 2-5, Quox-7 transcripts were found essentially in the ventral mesenchyme (neural crest-derived mesectoderm of the face and hypobranchial structures, somatopleure, and limbs) and also in a narrow dorsomedial band of cells of the superficial ectoderm and neural tube. This pattern is fundamentally similar to that reported for Hox-7/7.1, suggesting that the products of these genes play a similar role in the development of the different classes of vertebrates.