Apparent Turnover of Mitochondrial Deoxyribonucleic Acid and Mitochondrial Phospholipids in the Tissues of the Rat

Abstract

The apparent turnovers of mitochondrial DNA and of the phospholipids, cardiolipln, lecithin, and phosphatidyl ethanolamine, have been determined simultaneously in the mitochondria of rat liver, kidney, brain, and heart.The turnover rate of mitochondrial DNA in liver was similar to previously reported turnover rates of other mitochondrial components.Mitochondrial DNA has a half-life of 6.7 days in heart, 9.4 days in liver, 10.4 days in kidney, and about 31 days in brain.The turnover of mitochondrial phospholipids is complex: in the liver and kidney their turnover rates are similar to that of the mitochondrial DNA.In the other organs studied slower and nonexponential turnover rates were found.There was no apparent turnover of nuclear DNA in liver, kidney, or brain during the experiment.A relatively rapid rate of turnover with a half-life of about 30 days was found for heart nuclear DNA. Mitochondrisand other cell organelles such as chloroplasts have been shown to have a degree of autonomy (3-5).Mitochondria contain DNA which differs in molecular size, physical properties, and, in certain cases, base composition from nuclear