The International Journal of Developmental Biology

Int. J. Dev. Biol. 43: 563 - 566 (1999)

Vol 43, Issue 6

Artefactual gene induction during preparation of Xenopus laevis animal cap explants

Published: 1 September 1999

B Krain and A Nordheim

Institut für Molekularbiologie, Medizinische Hochschule Hannover, Germany.


The animal cap assay in Xenopus laevis was used to study the induction and regulation of the mesoderm-specific gene Xegr-1, a homolog of the mammalian egr-1 genes. Egr-1 is an immediate-early gene whose growth factor-stimulated transcriptional induction displays a transient activity profile and occurs independent of protein synthesis. The Xegr-1 promoter contains multiple serum response elements (SREs). In this paper we show that Xegr-1 is induced unspecifically during the process of animal cap preparation. Transcripts of Xegr-1 appear already 30 min after cutting of animal caps. Xfos, another SRE-regulated immediate-early gene, is induced with the same kinetics as Xegr-1. In contrast, the Xbra gene is not induced under the experimental conditions used. Xfos and Xegr-1 transcripts are not rapidly down-regulated after mechanical stimulation, but can be detected for up to 4 h later. Wounding-dependent Xegr-1 induction is reduced by injection of either mRNA coding for the dominant inhibitory forms of both the FGF receptor and the transcription factor Elk-1. Xegr-1 expression can be reinduced by mesoderm-inducing factors. These results led us to develop a new protocol for animal cap preparation, which circumvents the observed undesired artefactual gene activation events.

Full text in web format is not available for this article. Please download the PDF version.