PXEX, A VECTOR FOR EFFICIENT EXPRESSION OF CLONED SEQUENCES IN XENOPUS EMBRYOS

We describe the construction of pXeX, a plasmid vector that efficientl y expresses cloned sequences in Xenopus embryos. This plasmid contains the transcription regulatory regions from the Xenopus laevis elongati on factor-1 alpha-encoding gene (EF-1 alpha). Expression of cloned seq uences commences in blastula-stage embryos, coincident with transcript ional activation of the embryonic genome, and transcripts may persist until the tadpole stage of development.