ISOLATION AND EMBRYONIC EXPRESSION OF XEL-1, A NERVOUS SYSTEM-SPECIFIC XENOPUS GENE-RELATED TO THE ELAV GENE FAMILY

We have identified a new member of the elav gene family in Xenopus lae vis. This gene, Xel-1, like the other elav-related genes, encodes a pu tative RNA-binding protein that contains three RNA Recognition Motifs and is solely expressed in the nervous system. Xel-1 is most likely th e Xenopus homologue of Hel-N1, one of the three known human genes rela ted to elav. Xel-1 is not expressed in early neural precursors but rat her in differentiating neurons of the central nervous system, as well as in the cranial and the spinal ganglion cells. Xel-1 thus appears to be an early differentiation marker for both the central and the perip heral nervous system of Xenopus laevis.