The circadian gene Clock is restricted to the anterior neural plate early in development and is regulated by the neural inducer noggin and the transcription factor Otx2

The circadian cycle is a simple, universal molecular mechanism for imposing cyclical control on cellular processes. Here we have examined the regulati on of one of the key circadian genes, Clock, in early Xenopus development. We find that the expression of Clock is dependent on developmental stage, n ot on time per se, and is mostly restricted to the anterior neural plate. I t's expression can be induced by the secreted polypeptide noggin, and subse quently upregulated by Otx2. a transcription factor required for the determ ination of anterior fate. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.