Studies on mitochondria. II. Mitochondrial DNA of thoracic muscles of Schistocerca gregaria.

The buoyant densities of the nuclear and mitochondrial DNA from the thoracic muscles of Schistocerca gregaria were found to be 1 702 and 1.689 g/cm(3), respectively, corresponding to guanine plus cytosine (G + C) content of 42.2 and 30% A preliminary treatment of the mitochondrial pellet with DNase (25 degrees C, 20 min) is necessary to eliminate the contaminating nuclear DNA. The mitochondrial DNA renatures readily after heat denaturation and incubation at 65 degrees C. The DNA released from the mitochondrial pellet by osmotic shock consists of circular open and closed molecules with a contour length around 5 micro The instability of insect mitochondria in in vitro preparations is discussed.