Hybridisation studies on DNA isolated from Scenedesmus obliquus

Abstract

Chloroplast DNA was separated from the nuclear DNA of Scenedesmus obliquus by CsCl density gradient centrifugation and found to be of buoyant density 1.694 g/ml (nuclear DNA 1.712 g/ml). 32P-labelled RNA species from S. obliquus were hybridised to DNA in fractions of the gradient. Cytoplasmic rRNA, 4S RNA and 5S RNA hybridised to DNA of buoyant densities 1.706 g/ml, 1.71–1.73 g/ml and 1.70–1.72 g/ml respectively. Other rRNA, 4S RNA and 5S RNA species which were distinct from the cytoplasmic species hybridised to the light DNA and would appear to be of chloroplast origin.