Isolation of chloroplasts free from nuclear DNA contamination

A rapidly-banding component of animal DNA preparations that interferes with buoyant density studies

Rapidly-banding components of purified animal cell DNA's have been observed which have abnormal buoyant densities and show anomalous band profiles when centrifuged to equilibrium in cesium salts. These components interfere with the separation of animal DNA fractions and with the analysis of animal cell DNA's by buoyant density techniques. They can be detected by examining photographs of analytical buoyant-density ultracentrifugations before equilibrium has been reached. These rapidly-banding components are removed by phenol treatment.

Studies with cholroplast and mitochondrial DNA. I. Evidence of sequence homology between chloroplast and nuclear DNA (Broad Bean) and between mitochondrial and nuclear DNA (rat liver)

A mixture of broad bean chloroplast and nuclear DNA or rat liver mitochondrial and nuclear DNA was taken through a heating and annealing cycle, and examined by CsCl density gradient centrifugation. The formation of intermediates between the two DNAs during joint annealing was used as a method of detecting sequence homology in different DNA samples. Homology was found between chloroplast and nuclear DNA from broad bean and between mitochondrial and nuclear DNA from rat liver. Since this method produces only qualitative data no implication for possible nucleocytoplasmic relationship can be assessed.