XIF3, a Xenopus peripherin gene, requires an inductive signal for enhanced expression in anterior neural tissue.

A full-length cDNA clone for the Xenopus intermediate filament gene XIF3 has been isolated. It is very similar in sequence to the rat intermediate filament cDNA clone 73 that is thought to encode the neuronal intermediate filament protein 'peripherin'. By analysing dissected embryos, we show that XIF3 is expressed predominantly in anterior and dorsal structures and most strongly in the brain of the tailbud (stage 26) embryo. In situ hybridization shows XIF3 transcripts to be localized in neural tissue and especially in regions that most probably correspond to the motor neurones of the neural tube and to some cranial nerve ganglia. New XIF3 transcripts are first found at the start of gastrulation at a low level throughout the ectoderm and are not localized to the presumptive neurectoderm. Expression subsequently increases by about 10-fold in neural tissue, and requires an interaction of the mesoderm with overlying ectoderm. Because new transcripts are found predominantly in neural tissue of the head, this response can be used as a marker of anterior neural induction.