Is there specific transcription from isolated chromatin?

Hg-UMP-containing transcripts made from chick erythroid chromatins with E. coli RNA polymerase hybridize to chick globin cDNA. Contamination with endogenous globin RNA has been largely removed by purification on SH-agarose columns at 55 degrees C. Some endogenous globin mRNA sequences remain, probably as hybrids with "anti-sense" Hg-transcripts produced by RNA-dependent RNA synthesis. Heating to 115 degrees C before SH-agarose chromatography eliminates these contaminants. Hg-transcripts from adult and embryonic erythroid chromatins purified by this method are hybridized to globin cDNA; they contain a 4- to 6-fold higher proportion of globin-specific sequences (10-13 PPM) than do transcripts from brain chromatin. Dissociation of erythroid chromatins in salt and urea, followed by reconstitution using standard methods, destroys even this low degree of specificity.