Using dehistonized chromatin preparations, we have elicited antisera which react immunologically with chicken erythroid and HeLa cell chromatins. The antisera are highly specific and localize in the cell nucleus. According to our studies, the antigen is a complex of chromosomal proteins with DNA. Both the protein(s) and interacting DNA segments will be isolated and characterized in the serum of their chemical composition in biological significance. Using specific globin cDNA probes, we will continue our studies on the in vitro transcription of globin genes in isolated chicken erythroid chromatin. The effects of chromosomal nonhistone proteins and chromatin structure on the transcriptional regulatin of specific genes (globin, alpha U2 globulin, alpha-fetoprotein) will be also investigated.