Changes of fatty acid metabolism and oxidative phosphorylation of rat liver mitochondria during 3'-Me-DAB feeding

Respiration, activity of oleate oxidation and composition of the total fatty acids of rat liver were investigated in 3'-Me-DAB feeding. 1. Oxidative phosphorylation of rat liver mitochondria decreased temporarily at relatively earlier stages (about 2 to 3 weeks) in 3'-Me-DAB feeding. 2. The activity of oleate oxidation of rat liver mitochondria decreased rapidly to about one third of that in control groups after the start of 3'-Me-DAB feeding. 3. In the composition of the total fatty acids of rat liver, the proportion of oleic acid increased in 3'-Me-DAB groups. 4. Unknown octadecamonoenoic acid was observed in liver mitochondria of rat fed on 3'-Me-DAB. 5. Proportions of oleic and palmitoleic acids in liver tumors and mitochondria of liver tumors induced by 3'-Me-DAB feeding increased remarkably in contrast with decrease in those of palmitic and eicosapolyenoic acids. 6. A possibility was discussed about how higher level of oleate in the liver cells in azo dye feeding may be concerned with the tumor induction.</p

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

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

Phosphorylation of purine and pyrimidine nucleosides by isolated rat liver mitochondria

Formation of 5'-AMP, 5'-GMP, 5'-CMP and 5'UMP was confirmed in isolated rat liver mitochondria incubated with alpha-ketoglutarate, inorganic phosphate, purine nucleoside and pyrimidine nucleoside. Increased incorporation of 32Pi into ATP, GTP and UTP was observed by adding purine- and pyrimidine nucleosides. The phosphorylation of nucleosides was inhibited severely by arsenite and affected slightly by the addition of nuclear or post-mitochondrial fraction.</p

Uncoupling agent of oxidative phosphorylation from ascitic fluid of tumor bearing mice after X-irradiation

It was investigated to clarify the relationship between the composition of the lipid fractions obtained from the ascitic fluid of Ehrlich ascites tumor bearing mice and its uncoupling activity after whole body irradiation (1,000 r). 1. Oxidative phosphorylation of Ehrllch ascites tumor cells was loosely uncoupled with the addition of ascitic lipid fraction extracted from tumor bearing mice. 2. The uncoupling activity of the lipid fraction on the oxidative phosphorylation of the tumor cells increased after whole body irradiation. 3. Ascitic lipid fraction, especially acetone soluble fraction accelerated mitochondrial swelling, and the swelling action was increased remarkably by the whole body irradiation. 4. No significant changes were observed in the proportion of acetone soluble fraction to acetone insoluble fraction in the ascitic lipid after X-irradiation, and the proportion of the both fractions was approximately 9 : 1, respectively. 5, Main compositions of total and non-esterified fatty acids in the ascitic fluid obtained from the control and X-irradiated groups were palmitic, stearic, oleic, linoleic and palmitoleic acids, and the proportions of unsaturated acids, especially oleic and linoleic acids in both fatty acid fractions were greater in the X-irradiated group. 6. Remarkable increment of unsaturated fatty acid especially linoleic acid, was also observed in the total fatty acids of the tumor cells separated from the X-irradiated group. 7. It can be concluded that an uncoupling agent extracted from ascitic fluid of the X-irradiated group was a mixture of long-chain fatty acids, especially oleic and linoleic acids. 8. It was also discussed that uncoupling oxidative phosphorylation in liver mitochondria after whole body irradiation may be caused by a similar mechanism to that in the turnor cells.</p

Nucleic acids and protein synthesis in cancer cell mitochondria. II. Amino acid incorporation into proteins of rat liver and hepatoma cell mitochondria

The energy source required for the amino acid incorporation into mitochondrial proteins has been investigated and comparative study has also been made on the rate of the amino acid incorporation in rat liver and rat hepatoma cell mitochondria. 1. The incorporation of amino acid into the protein in intact mitochondria of rat liver increased by about 40% on the addition of &#945;-ketoglutarate and ADP, but no significant increase in the amino acid incorporation was observed on the addition of succinate and ADP. 2. The incorporation of amino acids into mitochondrial proteins was remarkably inhibited by the addition of respiratory inhibitors (cyanide, DNP at a high concentration). 3. The amino acid incorporation into mitochondrial proteins was scarcely or slightly inhibited by the addition of DNP at the concentration of 1×10-4M and insensitive to oligomycin (5 to 10 &#956;g/ml). 4. The amino acid incorporation into the protein in the endogenous substrate system of the mitochondria was considerably inhibited by the addition of arsenite, and this inhibition somewhat recovered on the addition of ADP plus succinate. 5. The rate of the amino acid incorporations between rat liver and hepatoma cell mitochondria was at the same level. 6. Discussions were made on the energy source required for the amino acid incorporation into mitochondrial proteins, on the rate of protein synthesis per mitochondrion isolated from rat liver- and hepatoma cells, and on the possibilities of contamination of bacteria or microsomes and of the adsorption of amino acids onto the mitochondria.</p

Localization of TCA cycle dehydrogenases in the mitochondria

The site of localization of TCA cycle dehydrogenases in mitochondria has been investigated by observing the dehydrogenase activities and fine structure of the fractionated samples after freezing and thawing or sonication of beef heart and rat liver mitochondria. 1. In the sonicated mitochondria, activities of malic and isocitric dehydrogenases were highest in the supernatant fraction centrifuged at 198,000 x g for 60 minutes, while the specific activity of a-ketoglutaric dehydrogenase was higher in the fluffy or residue fraction. The distribution of the activity of pyruvic dehydrogenase was similar to that of a-ketoglutaric dehydrogenase. 2. In a sucrose density gradient fractionation of the fluffy fraction obtained by centifugation of sonicated mitochondria at 198, 000 x g for 60 minutes, the activities of malic and pyruvic dehydrogenase were observed in the top (or low density) layer in the form of fine particles, while that of a-ketoglutaric dehydrogenase was observed in the middle (or medium density) layers in the form of aggregates of fine particles and membranous fragments. 3. In the samples fractionated after freezing and thawing of mitochondria, which were considered to be a relatively mild disruption, the specific activity of a-ketoglutaric dehydrogenase was higher in the residue (submitochondria) fraction than that in the supernatant fraction (centrifuged at 144,000 x g, 30 minutes), and the activity of malic dehydrogenase still remained significantly high in the residue fraction. 4. It was deduced that the TCA cycle dehydrogenases could be localized in the matrix of the mitochondria by a loose binding to the inner membrane.</p

Fractionation and characterization of euchromatin isolated from mouse ascites sarcoma cells

Euchromatin specimen prepared by the usual method formed large clumps and had various shapes under electron microscopy. A method of separation of the euchromatin specimen into chromatin fractions having relatively homogeneous form was examined and partial characterization of these fractions was carried out. The heavy euchromatin fraction was a large network of thin fibrils (about 100 A in diameter) and various thick fibers. The intermediate euchromatin fraction consisted of relatively homogeneous networks of thick knobby fibers (about 250 A in diameter). The light euchromatin fraction had metworks of thick fibers. These chromatin fractions were quantitatively prepared from sonicated nuclei of mouse ascites sarcoma cells. Twenty-one or twenty-two bands of non-histone proteins besides histones were detected in these chromatin fractions by SDS-polyacrylamide gel electrophoresis. There were significant differences in the electrophoretic patterns of non-histone proteins among these chromatin fractions.</p

Correlation of structure and function in the oxidative phosphorylation system of submitochondrial particles

1. After the centrifugation of sonicated heavy beef heart mitochondria at 75, 000 &#215; g for 10 minutes, the supernatant was centrifuged at 144, 000 &#215; g for 30 minutes. The residue was revealed being composed of vesicular inner membrane fragments (ETPH), about 600 to 1000 &#197;. in diameter, showing a morphological homogeneity and a high capacity of oxidative phosphorylation. 2. The Pia ratio of the ETPH in the presence of succinate and of NADH2 was 1.68 and 2.54, respectively, and the corrected Pia value for O2 gas equilibrium was 1. 01 and 1.40, respectively. 3. The capacity of oxidative phosphorylation in ETPH fraction was parallel to the activity of the oligomycin. sensitive ATPase in these fractions. 4. The P/0 ratio of ETPH was decreased to about 50 % by hypotonic treatment. The decrease of P/0 ratio was restored to the level of about 90 % by incubating the ETPH with ATP and BSA. In the instance where the P/0 ratio was low level in the hypotonic medium, the surface structure of ETPH was observed as a swollen form and the head pieces of the elementary particles were clearly observed in contrast to the solid surface structure of ETPH in the isotonic medium. 5. The P/0 ratio of ETPH was decreased to about 60 % by relatively severe sonication, and after separating the residue from the supernatant, that of the residue decreased further to about 40 %. The P/0 ratio of the residue was restored to the level before the separation on the addition of the supernatant containing oligomycin-insensitive ATPase. 6. A discussion was made on the correlation between the surface structure and the activities at terminal phosphorylation step of ETPH after the simple physico-chemical treatment.</p

RNA synthesis in mitochondria isolated from rat liver

Mitochondrial RNA (mtRNA) was synthesized from purine and pyrimidine nucleosides in coupling with oxidative phosphorylation using isolated mitochondria. The in vivo synthesized mtRNA was adenine-uracil rich and sedimented at about 20 S by sucrose density gradient centrifugation. A major part of the newly synthesized mtRNA was shown to be poly (A)-containing RNA by the resistance to the digestion with pancreatic RNase and RNase T1 and the affinity to poly (U)-Sepharose columns or Millipore filters.</p

Purification and some characteristics of liver cytosol cornin, an antimitotic substance from rat liver cytosol

Further purification and characterization are reported on rat cytosol cornin (RLCC), an antimitotic substance. Fraction I (purified RLCC) was purified more than 10-fold from crude RLCC with Sephadex G-50 column chromatography and showed a remarkable inhibitory effect on division of inseminated sea urchin eggs and mouse fibroblast cells. Fraction I was observed as one spot, and the molecular weight was estimated to be about 25,000 by thin layer gel filtration. Fraction I contained protein (92%) and RNA (8%), but the antimitotic activity was scarcely affected by treatment by pancreatic RNase. The protein of Fraction I was separated into two bands by SDS-polyacrylamide gel electrophoresis, and the molecular weight was estimated as 10,000 and 15,000, respectively. The 50% inhibition dose of Fraction I on the first division of inseminated sea urchin eggs and on proliferation of mouse L cells was about 2.5 X 10(-5) g/ml and 5 X 10(-4) g/ml, respectively. The yield of fraction I was about 35 mg from 100 g rat liver.</p