MITOCHONDRIAL RESISTANCE TO MASSIVE IRRADIATION IN VIVO. II. DENSITY- GRADIENT DISTRIBUTION OF THE MITOCHONDRIAL FRACTION AND ASSOCIATED ENZYMES.

Abstract Sucrose density gradient centrifugation was utilized to discern effects of massive γ-irradiation (250 and 1000 krad) on the mitochondrial fraction in pear fruit cells. Protein content and three enzymes, cytochrome oxidase, catalase and acid phosphatase were used to detect the presence of specific organelles along the sucrose gradient. A dose of 250 krad deterred mitochondrial fragmentation and losses in enzyme activities known to occur in the unirradiated, aging control cells. A 1000-krad dose, however, produced obvious manifestations of massive stress to the fruit and augmented the degenerative processes associated with cellular aging.