Transcriptional regulation of hemoglobin switching in chicken embryos.

We used recombinant chicken deoxyribonucleic acid clones containing embryonic and adult beta-globin genes and "runoff" endogenous nuclear transcription to investigate the expression of embryonic and adult beta-globin genes during hematopoiesis in the developing chicken embryo. Purified, cloned deoxyribonucleic acids were digested with various restriction enzymes, separated on agarose gels, blotted to nitrocellulose, and annealed with purified nuclear [32P]ribonucleic acid synthesized in vitro from embryonic or adult red cell nuclei. Transcription of the respective globin genes was assayed by hybridization of nuclear [32P]ribonucleic acid to specific restriction fragments containing adult or embryonic coding sequences. Our results indicate that little, if any, transcription from the adult or embryonic beta-globin genes is detectable in the heterologous red cell nuclei, even under conditions in which ribonucleic acid processing probably does not occur.