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Mitochondrial DNA's from respiratory-sufficient and cytoplasmic respiratory-deficient mutant yeast

1970; Elsevier BV; Volume: 48; Issue: 1 Linguagem: Inglês

10.1016/0022-2836(70)90216-0

1089-8638

Giorgio Bernardi, Marie Faures, G Piperno, Piotr P. Słonimski,

Molecular Biology Techniques and Applications

The mitochondrial DNA's from two “grande” yeast strains and three cytoplasmic “petite” mutants were isolated by hydroxyapatite chromatography and investigated in their chemical and physical properties. The buoyant densities of all DNA's were equal to 1.683 g/cm3, except for one from a petite strain which had a density equal to 1.678 g/cm3. The mitochondrial DNA's from the petite mutants were “reversible”, their buoyant densities and their ultraviolet absorptions showing very little or no increase after heating and fast cooling. In contrast, the DNA's from the grande cells showed an increase in buoyant density of 0.010 to 0.011 g/cm3 and a residual hyperchromicity of 10 to 12% upon the same treatment. In this case, both density and residual hyperchromicity were lowered by thermal treatment at 65 °C. The guanine plus cytosine contents of the DNA's from the grande strains were found to be 17.4 and 16.8%. Those of the DNA's from the petite mutants were 15.5, 15.6 and 12.6%. For all mitochondrial DNA's, the base compositions calculated from their buoyant densities and Tm values did not fit these obtained by analysis. A striking compositional heterogeneity was indicated by the ultraviolet melting curves of all mitochondrial DNA's. The distribution of the melting components of the DNA's from the grande strains was remarkably different from that of the DNA's from the petite strains. The first one was broad and asymmetric, the second one was multimodal with a small number of components. Furthermore, the DNA's from the different petite mutants showed distinct melting patterns.