A Xenopus homolog of a human p53-activated gene, PA26, is specifically expressed in the notochord

The LIM class homeodomain protein Xlim-1 is specifically expressed in the o rganizer and later in the notochord in Xenopus. By seeking genes which are activated by Xlim-1 in animal caps, we isolated a gene which encodes a prot ein highly homologous to human PA26-T2, a p53-inducible nuclear factor, whi ch we refer to as XPA26. Northern blot analysis showed that maternal transc ripts of XPA26 are detected at cleavage stages and reduced during gastrulat ion. Whole-mount in situ hybridization showed that zygotic transcripts of X PA26 were initially detected in the anterior portion of developing notochor d at neurula stages, and later in the entire notochord except its posterior region at tailbud stages. Thus the zygotic expression of XPA26 was detecte d exclusively in the notochord. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.