The mRNA expression patterns of E12 transcription factor in various developmental stages and adult tissues of carp

First-strand cDNA was synthesized from total RNA of larvae at hatching of t he carp Cyprinus carpio by reverse-transcription reaction. Subsequently, a cDNA clone encoding E12 transcription factor was isolated by PCR with sever al combinations of primers. The DNA fragment finally obtained comprised 849 and 593 bp of the coding and 3' non-coding regions, respectively, encoding a partial length of carp E12. The deduced amino acid sequence of carp E12 showed high identity with corresponding regions from other vertebrates (51- 81%), particularly in the basic helix-loop-helix domain (approximately 90%) . In northern blot analysis, carp E12 transcripts were detected at various developmental stages, suggesting that carp E12 is implicated in cell prolif eration and differentiation during ontogeny as those of other vertebrates. The mRNA signals were still recognized in the muscle from 7-month-old juven iles, while markedly reduced compared to those in embryos. Therefore, it se ems that carp E12 prays an important role in the formation of new myofibers even after hatching. Carp E12 transcripts were also expressed in various t issues, though with small quantities in the muscle, of adult fish aged 2 ye ars, suggesting that this transcription factor is involved in many tissue-s pecific gene transcriptions.