Conserved and divergent expression of T-box genes Tbx2-Tbx5S in Xenopus

We report here the identification of four members of T-box family genes, Xl tbx2-Xltbx5, in Xenopus. Two of them are probable pseudovariant genes of XT bx5 and ET, a putative Xenopus ortholog of Tbx3. We compared their expressi on patterns in both embryos and limbs. In embryos, expression of Xltbx2 and Xltbx3 showed novel diversities, such as Xltbx2 in the neural crest cells and Xltbx3 in the ventral spinal cord, together with mutual similarities in the following regions: dorsal retina, proctoderm, lateral line organ, ceme nt gland and cranial ganglia. The patterns in limbs were highly conserved w ith mouse and chick orthologs, including the limb-type specific expression of Xltbx4 and Xltbx5. In addition, RT-PCR analysis showed that they are exp ressed weakly even in adult limbs as previously reported in the newt. (C) 2 000 Elsevier Science Ireland Ltd. All rights reserved.