Search PubMed⌕ Search

Biomedical subjects

M Rabinowitz

Publications and source records attributed to M Rabinowitz.

At least 163 records · Page 9Linked to original sources
PubMed1971

Mitochondrial development in liver of foetal and newborn rats.

THE DEVELOPMENT OF THE INNER MITOCHONDRIAL MEMBRANE IN FOETAL AND NEONATAL RAT LIVER WAS STUDIED BY FOLLOWING THREE PARAMETERS: (1) the activity of several respiratory enzymes in homogenates and purified mitochondria, (2) the spectrophotometric determination of cytochrome content in the mitochondria and (3) the cardiolipin content in both homogenates and purified mitochondria. Respiratory-enzyme activities of homogenates of foetal liver were one-quarter to one-twentieth of those of homogenates of adult liver, and the enzyme specific activities in purified mitochondria from foetal liver were one-half to one-eighth of those in mitochondria from adult liver. The cardiolipin content of liver homogenates increased approximately twofold during the development period, but there was no significant change in the cardiolipin content of purified mitochondria. It is concluded that cell mitochondrial content approximately doubles in the immediate postnatal period. There was no evidence for an increase in the relative amount of cristae protein in mitochondria during this period to account for increases in mitochondrial enzyme specific activity, since cardiolipin and cytochrome concentrations remained unchanged and electron micrographs revealed no differences. The cause of the lower respiratory-enzyme specific activity in foetal liver mitochondria is unclear. Qualitative differences in respiratory units in foetal and mature animals are suggested.

Animals↗
PubMed1971

Isolation of Saccharomyces cerevisiae mitochondrial formyltetrahydrofolic acid:methionyl-tRNA transformylase and the hybridization of mitochondrial fMet-tRNA with mitochondrial DNA.

Formyltetrahydrofolic acid:methionyl-tRNA transformylase was isolated from Saccharomyces cerevisiae mitochondria and used to prepare yeast mitochondrial [(3)H]formylmethionyl-tRNA. This fMet-tRNA hybridizes with mitochondrial DNA but not with yeast nuclear or E. coli DNA. Unlabeled mitochondrial, but not extramitochondrial, tRNA competes in this reaction. tRNA was eluted from the hybrid and found to contain the label almost exclusively in fMet-tRNA. Yeast cytoplasmic fMet-tRNA formylated with Escherichia coli enzyme, and E. coli fMet-tRNA, do not hybridize with mitochondrial DNA. It is concluded that yeast mitochondrial tRNA(fMet) is a gene product of the mitochondrial genome.

DNA↗
PubMed1971

Cardiolipin content of wild type and mutant yeasts in relation to mitochondrial function and development.

The phospholipid composition of various strains of the yeast, Saccharomyces cerevisiae, and several of their derived mitochondrial mutants grown under conditions designed to induce variations in the complement of mitochondrial membranes has been examined. Wild type and petite (cytoplasmic respiratory deficient) yeasts were fractionated into various subcellular fractions, which were monitored by electron microscopy and analyzed for cytochrome oxidase (in wild type) and phospholipid composition. 90% or more of the phospholipid, cardiolipin was found in the mitochondrial membranes of wild type and petite yeast. Cardiolipin content differed markedly under various growth conditions. Stationary yeast grown in glucose had better developed mitochondria and more cardiolipin than repressed log phase yeast. Aerobic yeast contained more cardiolipin than anaerobic yeast. Respiration-deficient cytoplasmic mitochondrial mutants, both suppressive and neutral, contained less cardiolipin than corresponding wild types. A chromosomal mutant lacking respiratory function had normal cardiolipin content. Log phase cells grown in galactose and lactate, which do not readily repress the development of mitochondrial membranes, contained as much cardiolipin as stationary phase cells grown in glucose. Cytoplasmic mitochondrial mutants respond to changes in the glucose concentration of the growth medium by variations in their cardiolipin content in the same way as wild type yeast does under similar growth conditions. It is concluded that cardiolipin content of yeast is correlated with, and is a good indicator of, the state of development of mitochondrial membrane.

Carbon↗
PubMed1970

Haem a, cytochrome c and total protein turnover in mitochondria from rat heart and liver.

Haem a and cytochrome c were isotopically labelled in mitochondria from rat heart and liver after injection of delta-amino[2,3-(3)H(2)]laevulate, a specific haem precursor. [guanido-(14)C]Arginine or l-[4,5-(3)H(2)]leucine were used to label mitochondrial proteins. Half-lives were measured from biological decay in vivo and were similar (5.5-6.2 days) for haem a, cytochrome c and [(14)C]arginine-labelled proteins. Labelling of hepatic mitochondrial proteins with [(3)H(2)]leucine resulted in a prolonged apparent half-life.

Amino Acids↗