Our overall goal is to probe the functions of chromosomal proteins in embryonic development and gene control. We are studying functional and structural properties of stage-specific subtypes of histones. We will also take up the question of whether early subtypes become segregated in a subset of cells in the embryo. These studies will involve 1) isolation of each subtype in pure form; 2) determination of the chemical nature of the differences between them by peptide mapping and sequence analysis; 3) preparation of subtype-specific immune sera; 4) study of locations of the subtypes in the embryo of immunofluorescence; 5) examination of subtype-specific phosphorylation of histone H1; 6) a search for early embryonal histone subtypes in mammalian cells.