scholarly journals The significance of promitochondrial structures in rat liver for mitochondrial biogenesis

1973 ◽  
Vol 134 (3) ◽  
pp. 687-695 ◽  
Author(s):  
J. G. Satav ◽  
M. S. Rajwade ◽  
S. S. Katyare ◽  
M. S. Netrawali ◽  
P. Fatterpaker ◽  
...  
Keyword(s):  
Buoyant Density ◽  
Mitochondrial Fraction ◽  
The Other ◽  
Nucleic Acid Content ◽  
Differential Centrifugation ◽  
Thyroid Status ◽  
Double Membrane ◽  
Mitochondrial Fractions ◽  
Rna And Dna

1. The heavy, light and fluffy mitochondrial fractions obtained by differential centrifugation were further characterized with respect to their protein synthesizing ability in vitro, their nucleic acid content, buoyant density of their DNA and ultrastructure. 2. The light mitochondrial fraction synthesized proteins in vitro at a rate 4–5 times as high as heavy and fluffy mitochondria. The incorporation ability of this fraction was also maximally affected by the thyroid status of the animal. The radioactivity in leucyl-tRNA of the light mitochondrial fraction was about 3–4 times as high as that of the other two fractions. 3. The heavy, light and fluffy mitochondrial fractions contained small but consistent amounts of RNA and DNA. Although the DNA content was the same in all mitochondria fractions, the light mitochondria contained relatively more RNA. The buoyant density of DNA from all the fractions was 1.701g/cm3. 4. Electron microscopy revealed that the heavy mitochondria have a typical mitochondrial architecture, with densely packed cristae and a well developed double membrane. Light mitochondria were also surrounded by double membranes, but were smaller in size and contained less cristae. The fluffy fraction consisted of a mixture of well formed mitochondria and those in the process of degradation. 5. The significance of these findings in relation to mammalian mitochondrial genesis is discussed.

scholarly journals Effects of Cobalt on the Renal Erythropoietic Factor and Kidney Hydrolase Activity in the Rat

Blood ◽  
1973 ◽  
Vol 42 (6) ◽  
pp. 893-905 ◽  
Author(s):  
Robert J. Smith ◽  
James W. Fisher
Keyword(s):  
Enzyme Inhibitors ◽  
Mitochondrial Fraction ◽  
Hydrolase Activity ◽  
Marker Enzyme ◽  
Factor Activity ◽  
Rat Serum ◽  
Mitochondrial Fractions ◽  
Normal Rat ◽  
Mitochondrial Extract

Abstract In an experiment to determine the effects of cobalt on the renal erythropoietic factor and kidney hydrolase activity in the rat we obtained the following results: Cobalt produced significant increases in renal erythropoietic factor activity and plasma levels of erythropoietin which reached peak activity 12 hr after treatment. It also produced an increase in the activity of renal hydrolases, cathepsins A and B, which paralleled the increase in renal erythropoietic factor activity. Enzyme inhibitors which are specific for proteases, esterases, and metalloenzymes inhibited the activity of the renal erythropoietic factor in vitro. Polycythemic mice exposed to 7- and 8-day posthypoxic intervals still retained their ability to respond to in vitro generated erythropoietin when compared to mice treated on the fourth posthypoxic day. The erythropoietic activity generated by the light mitochondrial extract—normal rat serum (LME-NRS) reaction mixture was blocked by the antibody to erythropoietin. The relative concentrations of smooth and rough endoplasmic reticulum (microsomes) and vesicles (lysosomes) were approximately the same in the light mitochondrial fractions of kidneys from normal and cobalt-treated rats. Marker enzyme studies revealed primarily alkaline phosphatase activity in the light mitochondrial fraction. These studies correlate with electron micrographs of the LME which indicate a fraction composed mainly of microsomes. In addition, these data suggest a possible relationship between renal lysosomal hydrolase activity and the renal erythropoietic factor (Erythrogenin).

Properties of skeletal muscle mitochondria isolated from subsarcolemmal and intermyofibrillar regions

1993 ◽  
Vol 264 (2) ◽  
pp. C383-C389 ◽  
Author(s):  
A. M. Cogswell ◽  
R. J. Stevens ◽  
D. A. Hood
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Mitochondrial Protein ◽  
Mitochondrial Fraction ◽  
Biochemical Properties ◽  
Leucine Incorporation ◽  
Mitochondrial Protein Synthesis ◽  
Skeletal Muscle Mitochondria ◽  
Mitochondrial Fractions

Two mitochondrial fractions, termed intermyofibrillar (IMF) and subsarcolemmal (SS), were isolated from skeletal muscle, and their biochemical properties were related to differences in respiration and mitochondrial protein synthesis. State III respiration was 2.3- to 2.8-fold greater in IMF than in SS mitochondria. Site 1 inhibition of respiration with rotenone reduced this difference to 1.4-fold. When sites 1 and 2 were inhibited with antimycin, the 1.4-fold differences remained. The activities of cytochrome-c oxidase (CYTOX) and succinate dehydrogenase (SDH) could account for some of these differences, since CYTOX was 20% greater (P < 0.05) in IMF mitochondria, and SDH was 40% greater (P < 0.05) in SS mitochondria. Cytochromes a, b, c, and c1 contents were similar in the two fractions. Cardiolipin (CL) content was higher (P < 0.05) in SS mitochondria, indicating a less dense mitochondrial fraction with respect to CL. In vitro [3H]leucine incorporation was 1.8-fold higher (P < 0.05) in IMF than in SS mitochondria. Thus compositional differences between IMF and SS fractions exist, perhaps representing mitochondria at different stages of biogenesis. The biochemical and functional differences could not solely be due to differences in mitochondrial protein synthesis but could also be due to nuclear-directed protein synthesis specific to each mitochondrial fraction.

scholarly journals Preparation of Crude Subcellular Fractions by Differential Centrifugation

2002 ◽  
Vol 2 ◽  
pp. 1638-1642 ◽  
Author(s):  
John Graham
Keyword(s):  
Density Gradient ◽  
Buoyant Density ◽  
Mitochondrial Fraction ◽  
Subcellular Fractions ◽  
Low Density ◽  
Differential Centrifugation ◽  
Density Gradient Purification

The employment of differential centrifugation to prepare crude fractions of subcellular particles from homogenates is often a necessary first step to a subsequent purification of one or more particles on a density gradient. Buoyant density gradient purification of peroxisomes or lysosomes for example is almost invariably carried out on a light mitochondrial fraction so as to eliminate smaller particles that may have similar densities. Unless they are first removed, large rapidly sedimenting particles in homogenates may also disturb shallow gradients designed to fractionate small low-density microsomes.

scholarly journals The biosynthesis of brain gangliosides. Separation of membranes with different ratios of ganglioside sialylating activity to gangliosides

1977 ◽  
Vol 168 (3) ◽  
pp. 325-332 ◽  
Author(s):  
C A Landa ◽  
H J F Maccioni ◽  
A Arce ◽  
R Caputto
Keyword(s):  
Membrane Fraction ◽  
Time Course ◽  
Mitochondrial Fraction ◽  
Subcellular Fractions ◽  
Synthetase Activity ◽  
Acetylneuraminic Acid ◽  
Mitochondrial Fractions ◽  
Brain Gangliosides

Brain subcellular fractions were analysed for ganglioside-sialylating activity by measuring the incorporation of N-[3H]acetylneuraminic acid from CMP-N-[3H]acetylneuraminic acid into endogenous ganglioside acceptors (endogenous incorporation) and into exogenous lactosyceramide (haematoside synthetase activity). The ratios of endogenous incorporation to gangliosides and of haematoside synthetase to gangliosides for the synaptosomal and mitochondrial fractions from a washed crude mitochondrial fraction were lower than those obtained for other membrane fractions. The differences appear to reflect intrinsic characteristics of each membrane fraction. The results of labelling in vitro and the time course of labelling of gangliosides of the different subcellular fractions in vivo after injection of N-[3H]acetylmannosamine are consistent with the possibility of a subcellular site for synthesis of gangliosides different from that of ganglioside deposition.

THE ACTION OF SERUM GONADOTROPHIN ON GLUTAMIC-OXALACETIC TRANSAMINASE IN THE RAT OVARY

1965 ◽  
Vol 49 (3) ◽  
pp. 379-387 ◽  
Author(s):  
B. Eckstein ◽  
Z. Paster
Keyword(s):  
Electrophoretic Mobility ◽  
Soluble Fraction ◽  
Mitochondrial Fraction ◽  
Supernatant Fraction ◽  
List Type ◽  
Differential Centrifugation ◽  
Glutamic Oxalacetic Transaminase ◽  
Enzyme Form ◽  
Rat Ovary

ABSTRACT The mechanism by which glutamic-oxalacetic transaminase (GOT) activity is increased in the rat ovary, following gonadotrophin treatment, was studied. It was found: Differential centrifugation of ovarian homogenate showed that there was an increased enzyme activity in the supernatant fraction. The GOT located in the mitochondrial fraction could be activated in vitro by incubating this fraction for several hours. Such treatment did not alter the activity of the enzyme in the supernatant fraction. Electrophoretic separation of the subcellular fractions showed the presence of the same two isoenzymes both in the mitochondrial and in the supernatant fractions. Only small amounts of the fast moving isoenzyme (GOT II) were present in the supernatant fraction, while the difference in quantity between the two isoenzymes in the mitochondria was less marked. Gonadotrophin stimulation intensified only the slow moving enzyme (GOT I) in the supernatant. Examination of the electrophoretic mobility of the enzyme released by the mitochondria into the incubation medium after in vitro activation showed that only GOT I was released by this treatment. The apparent Km for both L-aspartate as well as for α-ketoglutarate in the supernatant fraction remained unaltered by gonadotrophin stimulation, while the apparent Km were changed in the mitochondrial fraction of the hormone treated rats. These observations led to the hypothesis that gonadotrophin stimulation activates GOT in the rat ovary by transfering a latent mitochondrial GOT to the cell sap. In previous publications from this laboratory (Eckstein & Shain 1963; Eckstein 1963; and others), it was reported that gonadotrophins with follicle stimulating activity considerably enhance the glutamic-oxalacetic transaminase (GOT) activity in the rat ovary, while purified LH (NIH-LH-Sl) is inactive in this respect. Isoenzymes* of GOT have been reported for a great variety of organs (Boyd 1961, 1962; Katunuma 1962; Decker & Rau 1963; Fleisker et al. 1960; Augustinsson & Erne 1961). It has been shown (Boyd 1961), that two forms of GOT in the liver can be separated by differential centrifugation. One form adheres to the mitochondria, while the second enzyme is found in the soluble fraction. These two isoenzymes differ in their substrate affinities, pH dependance and electrophoretic mobility. The GOT in the mitochondria is in a latent form, and can be activated by release into the soluble fraction. The following experiments show that the rat ovary also contains at least two GOT isoenzymes; and that serum gonadotrophin (PMS) probably activates GOT by the release of one enzyme form from the mitochondria into the soluble fraction.

scholarly journals Preparation and properties of mitochondria derived from synaptosomes

1976 ◽  
Vol 154 (2) ◽  
pp. 423-432 ◽  
Author(s):  
J C. K. Lai ◽  
J B. Clark
Keyword(s):  
Citrate Synthase ◽  
Tricarboxylic Acid Cycle ◽  
Buoyant Density ◽  
Mitochondrial Fraction ◽  
Brain Mitochondria ◽  
Tricarboxylic Acid ◽  
Metabolic Compartmentation ◽  
Mitochondrial Fractions ◽  
Zonal Separation ◽  
Synaptic Mitochondria

A method has been developed whereby a fraction of rat brain mitochondria (synaptic mitochondria) was isolated from synaptosomes. This brain mitochondrial fraction was compared with the fraction of “free” brain mitochondria (non-synaptic) isolated by the method of Clark & Nicklas (1970). (J. Biol. Chem. 245, 4724-4731). Both mitochondrial fractions are shown to be relatively pure, metabolically active and well coupled. 2. The oxidation of a number of substrates by synaptic and non-synaptic mitochondria was studied and compared. Of the substrates studied, pyruvate plus malate was oxidized most rapidly by both mitochondrial populations. However, the non-synaptic mitochondria oxidized glutamate plus malate almost twice as rapidly as the synaptic mitochondria. 3. The activities of certain tricarboxylic acid-cycle and related enzymes in synaptic and non-synaptic mitochondria were determined. Citrate synthase (EC 4.1.3.7), isocitrate dehydrogenase (EC 1.1.1.41) and malate dehydrogenase (EC 1.1.1.37) activities were similar in both fractions, but pyruvate dehydrogenase (EC 1.2.4.1) activity in non-synaptic mitochondria was higher than in synaptic mitochondria and glutamate dehydrogenase (EC 1.4.1.3) activity in non-synaptic mitochondria was lower than that in synaptic mitochondria. 4. Comparison of synaptic and non-synaptic mitochondria by rate-zonal separation confirmed the distinct identity of the two mitochondrial populations. The non-synaptic mitochondria had higher buoyant density and evidence was obtained to suggest that the synaptic mitochondria might be heterogeneous. 5. The results are also discussed in the light of the suggested connection between the heterogeneity of brain mitochondria and metabolic compartmentation.

scholarly journals Aromatisation of steroids in the bivalve Mytilus trossulus

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6953 ◽  
Author(s):  
Anna Hallmann ◽  
Lucyna Konieczna ◽  
Justyna Swiezak ◽  
Ryszard Milczarek ◽  
Katarzyna Smolarz
Keyword(s):  
Mitochondrial Fraction ◽  
Inhibitory Effect ◽  
In Vivo Studies ◽  
Limiting Factor ◽  
Mytilus Trossulus ◽  
Mitochondrial Fractions ◽  
Estrogen Synthesis ◽  
Enzymatic Complex

In this study, we demonstrated the presence of the enzymatic complex able to perform aromatization (estrogen synthesis) in both, the microsomal and mitochondrial fractions of gills and gonads from Mytilus trossulus. Based on in vitro experiments, we highlighted the importance of temperature as the limiting factor of aromatisation efficiency (AE) in mussels. After testing range of temperatures (4–23 °C), the highest AE was found during incubation at 8 °C and pH 7.6 (41.66 pmol/h/mg protein in gills and 58.37 pmol/h/mg protein in gonads). The results were confirmed during field studies where the most efficient aromatisation occurred in bivalves collected in spring while the least effective in those collected in winter. During in vitro studies, AE turned out to be more intensive in female gonads than in male gonads. The process was also more intensive in mitochondrial fraction than in microsomal one (62.97 pmol/h/mg protein in male gills and 73.94 pmol/h/mg protein in female gonads). Enzymatic complex (aromatase-like enzyme) catalysing aromatisation in mussels was found to be insensitive to inhibitory effect of selective inhibitors of mammalian aromatase such as letrozole and anastrazole, suggesting its different structure from vertebrate aromatase. Further in vivo studies using 13C-labeled steroids at 8 °C temperature window confirmed that bivalves are able to uptake testosterone and androstenedione from the ambient environment and metabolise them to estrone and 17β-estradiol thus confirming endogenous estrogen’ synthesis.

scholarly journals Degradation of nucleic acids in the rumen

1973 ◽  
Vol 29 (2) ◽  
pp. 331-345 ◽  
Author(s):  
A. B. McAlian ◽  
R. H. Smith
Keyword(s):  
Nucleic Acids ◽  
Thin Layer ◽  
Degradation Products ◽  
Rumen Fluid ◽  
The Other ◽  
Pyrimidine Bases ◽  
Layer Chromatography ◽  
Rna And Dna

1. Nucleic acids introduced into the rumens of calves, or incubated with calf, sheep or cow rumen contents in vitro, were rapidly destroyed.2. The degradation products formed were separated and identified by means of column chromatography on Sephadex G-10 Dextran gel and thin-layer chromatography on cellulose.3. In vitro, RNA was rapidly (within 1 h) converted into ultrafilterable oligo-and mono-nucleotides, nucleosides, purine and pyrimidine bases. After 4 h, only the bases xanthine, hypoxanthine and uracil remained, having increased at the expense of the other constituents.4. DNA gave similar products but with a much greater proportion of ultrafilterable oligoand mono-nucleotide material which remained as a major component even after 4 h. The only bases present in appreciable amounts were thymine, hypoxanthine, uracil and xanthine.5. The same products accumulated temporarily in vivo, after addition of RNA or DNA to the rumens of calves, and were found also, in small amounts, in corresponding samples of duodenal digesta. The products disappeared from the rumen at a greater rate than could be accounted for by transfer to the duodenum.6. Cell-free preparations from calf rumen fluid contained enzymes which converted RNA and DNA into products which appeared to be ultrafilterable oligonucleotides.7. When ground hay was incubated with whole rumen contents the nucleic acids in the hay were degraded to a mixture of nucleotides, nucleosides and bases, almost as readily as were pure nucleic acids.

scholarly journals Kinetics and mechanisms of catalase in peroxisomes of the mitochondrial fraction

1971 ◽  
Vol 122 (2) ◽  
pp. 225-233 ◽  
Author(s):  
B. Chance ◽  
N. Oshino
Keyword(s):  
Hydrogen Peroxide ◽  
Rat Liver ◽  
Fold Increase ◽  
Mitochondrial Fraction ◽  
Hydrogen Donor ◽  
Urate Oxidase ◽  
Mitochondrial Fractions ◽  
Hydrogen Peroxide Generation ◽  
State 1

1. The primary intermediate of catalase and hydrogen peroxide was identified and investigated in peroxisome-rich mitochondrial fractions of rat liver. On the basis of kinetic constants determined in vitro, it is possible to calculate with reasonable precision the molecular statistics of catalase action in the peroxisomes. 2. The endogenous hydrogen peroxide generation is adequate to sustain a concentration of the catalase intermediate (pm/e) of 60–70% of the hydrogen peroxide saturation value. Total amount of catalase corresponds to 0.12–0.15nmol of haem iron/mg of protein. In State 1 the rate of hydrogen peroxide generation corresponds to 0.9nmol/min per mg of protein or 5′ of the mitochondrial respiratory rate in State 4. 3. Partial saturation of the catalase intermediate with hydrogen peroxide (pm/e) in the mitochondrial fraction suggests its significant peroxidatic activity towards its endogenous hydrogen donor. A variation of this value (pm/e) from 0.3 in State 4 to 0 under anaerobic conditions is observed. 4. For a particular preparation the hydrogen peroxide generation rate in the substrate-supplemented State 4 corresponds to 0.17s-1 (eqn. 6), the hydrogen peroxide concentration to 2.5nm and the hydrogen-donor concentration (in terms of ethanol) to 0.12mm. The reaction is 70% peroxidatic and 30′ catalatic. 5. A co-ordinated production of both oxidizing and reducing substrates for catalase in the mitochondrial fraction is suggested by a 2.2-fold increase of hydrogen peroxide generation and a threefold increase in hydrogen-donor generation in the State 1 to State 4 transition. 6. Additional hydrogen peroxide generation provided by the urate oxidase system of peroxisomes (8–12nmol of uric acid oxidized/min per mg of protein) permits saturation of the catalase with hydrogen peroxide to haem occupancy of 40′ compared with values of 36′ for a purified rat liver catalase ofk1=1.7×107m-1·s-1 and k′4=2.6×107m-1· s-1(Chance, Greenstein & Roughton, 1952). 7. The turnover of the catalase ethyl hydrogen peroxide intermediate (k′3) in the peroxisomes is initially very rapid since endogenous hydrogen peroxide acts as a hydrogen donor. k′3 decreases fivefold in the uncoupled state of the mitochondria.

Enhancement of ADP-induced Platelet Aggregation by Adrenaline in Vivo and Its Prevention

1973 ◽  
Vol 29 (02) ◽  
pp. 490-498 ◽  
Author(s):  
Hiroh Yamazaki ◽  
Itsuro Kobayashi ◽  
Tadahiro Sano ◽  
Takio Shimamoto
Keyword(s):  
Platelet Count ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
The Other ◽  
Endothelial Surface ◽  
Important Interaction ◽  
Blood Coagulability ◽  
The Difference

SummaryThe authors previously reported a transient decrease in adhesive platelet count and an enhancement of blood coagulability after administration of a small amount of adrenaline (0.1-1 µg per Kg, i. v.) in man and rabbit. In such circumstances, the sensitivity of platelets to aggregation induced by ADP was studied by an optical density method. Five minutes after i. v. injection of 1 µg per Kg of adrenaline in 10 rabbits, intensity of platelet aggregation increased to 115.1 ± 4.9% (mean ± S. E.) by 10∼5 molar, 121.8 ± 7.8% by 3 × 10-6 molar and 129.4 ± 12.8% of the value before the injection by 10”6 molar ADP. The difference was statistically significant (P<0.01-0.05). The above change was not observed in each group of rabbits injected with saline, 1 µg per Kg of 1-noradrenaline or 0.1 and 10 µg per Kg of adrenaline. Also, it was prevented by oral administration of 10 mg per Kg of phenoxybenzamine or propranolol or aspirin or pyridinolcarbamate 3 hours before the challenge. On the other hand, the enhancement of ADP-induced platelet aggregation was not observed in vitro, when 10-5 or 3 × 10-6 molar and 129.4 ± 12.8% of the value before 10∼6 molar ADP was added to citrated platelet rich plasma (CPRP) of rabbit after incubation at 37°C for 30 second with 0.01, 0.1, 1, 10 or 100 µg per ml of adrenaline or noradrenaline. These results suggest an important interaction between endothelial surface and platelets in connection with the enhancement of ADP-induced platelet aggregation by adrenaline in vivo.

Sign in / Sign up

Export Citation Format

Share Document