Template properties of embryo chromatin from eggs of the milkweed bug, Oncopeltus fasciatus

A method is described for the isolation of chromatin from eggs of the milkweed bug, Oncopeltus fasciatus. An analysis of changes in the macromolecular constituents of this chromatin at different developmental stages shows that, as the genome becomes less active in the synthesis of RNA, the histone/DNA ratio increases and the RNA/DNA ratio decreases. The ability of chromatin to act as a template (as measured by the synthesis of RNA) also diminishes from a peak activity which corresponds to the maximum rate of RNA synthesis previously determined by in vivo experiments. A causal connection between these events seems plausible as does a relationship between the changes in chemical composition and template activity of the chromatin.