Xenopus elav-like genes are differentially expressed during neurogenesis.

In Xenopus, three neural-specific elav-like genes (ELGs) have been identified, elrB/Xel-1, elrC and elrD. With the aim to highlight possible differences in the regulation of these genes, we compared their expression patterns during development. We had previously shown that elrB is expressed from the early tailbud stage onwards, in both the central and peripheral nervous system. Here we show that both elrC and elrD are expressed earlier than elrB in the developing neural tube and the cranial ganglia, with different temporal specificities. Double in situ hybridizations on brain cross-sections allowed us to define precisely the expression domains of elrB, elrC and elrD in the brain at the tailbud stage. What emerges from this study is a differential distribution of ELGs transcripts in the hindbrain. Also, double labeling with a motor neuron marker shows that in stage 41 tailbud embryos, elrD remains strongly expressed in motor neurons whereas elrC is mostly expressed in non-motor neuron cells.