Mitochondrial Protein and RNA Synthesis of X-Irradiated Mouse Livers

Abstract

The effects of 2000 R on protein and RNA synthesis of mouse liver mitochondria were determined. After 40-minute injection in vivo of14 C-leucine or3 H-uridine the uptake of both isotopes by the irradiated liver mitochondria was 80% and 36% higher respectively than control. Mitochondria from x-irradiated livers also incorporated 40% more14 C-leucine and 12% more ${}^{3}{\rm H}\text{-}{\rm UTP}$ during 40 minutes incubation in vitro at 37°C than control. The distribution of nascent protein and RNA in submitochondrial fractions after in vitro incorporation of14 C-leucine or ${}^{3}{\rm H}\text{-}{\rm UTP}$ indicated that the mitochondrial membrane fraction from x-irradiated livers incorporated 12.5% more ${}^{3}{\rm H}\text{-}{\rm UTP}$ and 34% more14 C-leucine. The supernatant (excluding mito-ribosomal particles) incorporated 58.5% more ${}^{3}{\rm H}\text{-}{\rm UTP}$ and 103% more14 C-leucine than control. The sedimentation profile of mito-ribosomes of control showed a higher proportion of particles in th...