作者: Oliver C. Richards , Robert S. Ryan
DOI: 10.1016/0022-2836(74)90574-9
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摘要: Abstract Replication of mitochondrial DNA was investigated by a density transfer experiment in strain Euglena gracilis lacking chloroplast DNA. uniformly labeled medium containing 32P-labeled inorganic phosphate and [3H]adenine the presence heavy-density label transferred to but no following removal label. nuclear within these cells used as an internal control. The densities ratios peaks were those expected for strict semiconservative replication. In contrast, replication dispersive, illustrated results: (1) both native denatured exhibited single peak at 1.1 2.2 cell doublings after transfer. (2) specific activity 3H-labeled varied across or DNA, indicating heterogeneous population molecules exhibiting different degrees radioisotope labeling. This dispersive could involve either multiple recombination events extensive turnover mixture both. Extensive dispersion sample obtained is shown persistence same duplex reduced molecular weight 6 × 105 shearing. Two measures rate from decrease 3H-specific activities during experiment. average rates indicates that replicates least 1.5 times fast Since there constant ratio DNA:nuclear logarithmic culture, calculated have half-life 1.8 doublings.