ORIGINS OF MITOCHONDRIAL RIBONUCLEIC ACIDS IN TETRAHYMENA PYRIFORMIS

Mitochondria contain 2 classes of ribonucleic acid (RNA), one soluble RNA (sRNA) and the other RNA referred to as pRNA which can be extracted from the pellet sedimentable after centrifugation of a mitochondrial lysate at 105,000g for 90-120 min. The origins of these RNAs were examined by DNA-RNA hybridization studies. The pRNA shows specific hybridization with mitochondrial deoxyribonucleic acid (DNA) up to 6.8% (RNA/DNA x 100) while sRNA does not hybridize to a significant extent. A large portion of mitochondrial sRNA is not transcribed from mitochondrial DNA.