A novel chicken homeobox-containing gene expressed in neurulating embryos.

We have isolated a cDNA clone from chicken embryo that contains a homeobox sequence (CHox-cad2). Analysis at the nucleotide and amino acid levels revealed closest similarity to the Xenopus Xcad1 and to other homeoboxes related to Drosophila caudal. RNA blot analysis showed hybridization of CHox-cad2 to two transcripts of 2.6 and 1.5 kb, present at day 1 of embryogenesis (E1). Using the highly sensitive polymerase chain reaction (PCR) to amplify cDNAs from embryonic RNAs from E0 (unincubated blastoderm) to E4, we confirmed the restricted expression of this homeobox sequence to the period of neurulation (E1).