Cell-specific antigens in chicken erythroid nuclei: species specificity

Abstract

Antisera raised to dehistonized chicken reticulocyte chromatin were tested for their cell and species specificity. Quantitative microcomplement fixation and immunohistochemical localization revealed the presence in chromatin of erythroid cell-specific nonhistone protein antigen(s). The antigenic specificity was shown to depend on the association of the antigenic protein(s) with deoxyribonucleic acid (DNA). Although the antisera were exceptionally cell specific, they cross-reacted with erythroid cells of other avian species. The extent of cross-reactivity was found to approximate the phylogenetic distances of the tested avian species. Erythroid cells from fish and amphibians were not reactive. Reconstitution experiments of partially purified chicken reticulocyte chromosomal nonhistone protein antigens with DNAs isolated from several vertebrate species showed that the species specificity of the antigenic complexes is determined principally by the species origin of the nonhistone proteins. Our results show that a cell-specific chromosomal nonhistone protein(s) has undergone evolutionary change and the relative immunological differences are consistent with the accepted phylogenetic distances of the species examined.

Immunologically specific complexes of chromosomal nonhistone proteins with deoxyribonucleic acid in chicken erythroid nuclei

“…The specificity of our antisera was assayed by complement fixation in the presence of intact or dehistonized chromatins. In accord with our previous experience (Krajewska et al, 1979), antibodies to dehistonized chicken reticulocyte chromatin did not react immunologically with intact or dehistonized chromatins isolated from various nonerythroid tissues of domestic fowl or other vertebrate species. Complement fixation observed with intact chicken erythrocyte chromatin was only marginal, indicating that considerable qualitative or quantitative changes might have occurred in erythroid chromatin during its final maturation.…”

“…In contrast to some other tissues (e.g., rat liver), antibodies to dehistonized chicken erythroid could be obtained relatively easily with most rabbits responding to the immunological challenge. These antisera did not cross-react with chromatins of other cell types, but they recognized erythrocyte chromatins of other avian species related to domestic fowl (Krajewska et al, 1979).…”

“…Associations of Cell-Specific Complexes of Chromosomal Nonhistone Proteins and DNA with Structural Elements of Chromatin, Since the immunological specificity could be observed only when nonhistone proteins were associated with DNA and not when pure DNA or nonhistone proteins were assayed alone (Krajewska et al, 1979), it was decided to study the antigenic complexes in context with chromatin structure as revealed by digestion with nucleases. Extensive digestion with nucleases completely abolished the complement fixation activity of reticulocyte chromatins (Figure 3).…”

“…No preferential accumulation of globin-specifying DNA sequences could be found in this nuclease-resistant DNA. The protein fraction containing the immunologically cell-specific complexes in chicken erythrocyte chromatin was glycosylated and moderately acidic (by amino acid analysis) with an electrophoretically determined Mr of ~90 000. nificant, extent with isolated erythrocyte chromatin (Krajewska et al, 1979). The protein component of the nonhistone protein-DNA complex responsible for the latter reaction specificity was isolated and partially characterized.…”