CHLOROPLAST DNA IN CHLAMYDOMONAS

Abstract

A method was developed for the isolation of relatively intact chloroplasts from the alga Chlamydomonas. These chloroplasts contained about 3% of the cellular DNA, of which 25-40% (in 3 separate preparations) consisted of a satellite band with a buoyant density of 1.702 gm/cm3 and GC content of 39.3%. The enrichment of satellite DNA in the chloroplast extract 7-fold over its concentration in total cell extracts provides strong evidence for its association with the chloroplast in vivo. Light microscope examination of the isolated chloroplast preparations indicated very low contamination with other cell particulates.