Studies on spinach chloroplast and nuclear DNA using large-scale tissue preparations.

A method for the large-scale preparation of spinach chloroplasts using the Spinco Model L-4 zonal ultracentrifuge and for the extraction of DNA from the chloroplasts is described. Thirty-five percent of the chloroplast DNA (rho = 1.706 g/cc) differs from nuclear DNA (rho = 1.695 g/cc) in buoyant density. T(m), base composition, and renaturation properties. Sixty-five percent of the chloroplast DNA (rho = 1.696 g/cc) has the same buoyant density and T(m) as nuclear DNA, but it differs in base composition and renaturation properties.