Structure and replication of Euglena gracills chloroplast DNA

The DNA molecule from chloroplasts of Euglena gracilis, strain Z, has been examined to determine (1) the structure and molecular weight of the molecule, (2) the mechanisms of replication of the molecule and (3) the ability of the molecule to replicate autonomously. The chloroplasts were found to contain circular DNA molecules 44 mm in contour length corresponding to a molecular weight of 92 million daltons. It was shown that the molecule replicated by a semiconservative mechanism with a half-life of 1.1 cell doublings. Also, the DNA molecule could not be replicated in the absence of cytoplasmic protein synthesis, but could be replicated in the absence of protein synthesis in the chloroplast.