Developmental expression of AmphiWnt1, an amphioxus gene in the Wnt1/wingless subfamily.

A full-length Wnt1 gene (AmphiWnt1) was isolated from amphioxus. Expression is first detectable in the gastrula around the lip of the blastopore. By the early neurula, transcription is in the mesendoderm near the closed blastopore, but is down-regulated in the overlying ectoderm. In the late neurula, expression is limited to the posterior wall of the neurenteric canal. Later in development, AmphiWnt1 transcripts can no longer be detected. AmphiWnt1 has no counterpart of the predominant expression domains of vertebrate Wnt1 genes in the neural tube, but its expression may be more comparable to that of wingless in the invaginating hindgut primordium of insects.