pXeX, a vector for efficient expression of cloned sequences in Xenopus embryos.

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