Nucleic acids and protein synthesis in cancer cell mitochondria. I. Nucleic acids in rat hepatoma mitochondria

Abstract

The contents of nucleic acids in rat liver and hepatoma mitochondria and the physico-chemical properties on DNA's isolated from these mitochondria were comparatively investigated. The results are briefly summarized as follows. 1. The contents of DNA and RNA per mg protein of the hepatoma cell mitochondria were about 10 and 2 to 4 times higher than those of rat liver mitochondria, respectively. 2. The &#955; max. and &#955;min. values of DNA isolated from the hepatoma mitochondria were 257 m&#956; and 231 m&#956;, respectively and those of DNA isolated from the nuclei were 259 m&#956; and 233 m&#956;, respectively, in saline-citrate, pH 7.0. 3. Three fractions of mitochondrial DNA were obtained by the sucrose density gradient and these DNA fractions corresponded, probably, to about 30 S, and 20 S and 14 S DNA's. 4. There was little difference in base compositions between nuclear and mitochondrial DNA's of the hepatoma cells. 5. The degree of hybridization between the nuclear and mitochondrial DNA's of the hepatoma cells was almost the same as that between the nuclear and nuclear DNA's of the hepatoma cells, and somewhat higher than that between the nuclear DNA of rat liver and the nuclear DNA of hepatoma cells. 6. &#34;Highly twisted&#34; circular, &#34;open&#34; circular and linear forms were observed in the DNA preparations of the hepatoma mitochondria. The average values of contour lengths of rat liver and the hepatoma DNA's observed at high frequency were 5.3 &#956; and 4.5 &#956;. 7. A discussion was made on the relation between the genetic informations of mitochondrial DNA and the formation of a mitochondrion in rat liver and the hepatoma cells.</p