scholarly journals STUDIES ON CELL METABOLISM AND CELL DIVISION

1936 ◽  
Vol 20 (2) ◽  
pp. 173-184 ◽  
Author(s):  
M. E. Krahl ◽  
G. H. A. Clowes
Keyword(s):  
Oxygen Consumption ◽  
Cell Division ◽  
Cell Metabolism ◽  
Substituted Phenols ◽  
Experimental Conditions ◽  
Arbacia Punctulata ◽  
Oxidation Reduction ◽  
Rate Of Oxygen Consumption ◽  
Considerable Support ◽  
Stimulation Of

The dihalo and trihalophenols, and phenols containing both halo and nitro substituents in the same molecule, produce, in fertilized eggs of Arbacia punctulata, a rise in rate of oxygen consumption and a reversible block to cell division. To define the conditions which affect the degree of this activity, the following factors have been varied: the arrangement of substituents in the molecule, the concentration of reagent, and the time after fertilization at which the reagent is added. The stimulation of oxygen consumption and reversible block to cell division produced by the dihalophenols are qualitatively the same as those previously produced in fertilized Arbacia eggs by certain dinitrophenols. To yield optimum respiratory effect and maximum division block, it usually requires a higher concentration of dihalo than of the corresponding dinitrophenol. For example, with fertilized Arbacia eggs at 20°C. 2,4-dinitrophenol, in optimum concentration of 3 x 10–5 molar, raises oxygen consumption to 292 per cent of normal (4). The corresponding values for two dihalo analogues are: 2,4-dichlorophenol, 10–4 molar and 236 per cent; 2,4-dibromophenol, 6 x 10–5 molar and 282 per cent. The halophenols differ from the nitrophenols in two interesting respects: (a) The monohalophenols produce little or no oxidative stimulation or division block in fertilized Arbacia eggs; p-nitrophenol is very active in both respects. (b) The symmetrical trihalophenols have an appreciable ability to stimulate oxygen consumption and block division; symmetrical trinitrophenol is inactive in both respects (4). The increases in oxygen consumption produced in fertilized Arbacia eggs by 2,4-dichloro and 2,4-dinitrophenol are larger than the percentage increases given by methylene blue and o-cresol indophenol under the same experimental conditions. The dihalo and dinitrophenols produce a reversible block to the cell division of fertilized marine eggs. The oxidation-reduction indicators, in contrast to the dihalo and dinitrophenols, block cell division irreversibly and fertilized eggs of Arbacia do not recover from optimum respiratory stimulating concentrations of these oxidation-reduction dyes. The present experiments with halophenols are in harmony with and lend considerable support to the hypothesis (4) that nitro and similarly substituted phenols derive their biological activity from the presence and properties of the phenolic OH group, as modified by proper substitution in the phenolic benzene ring.

scholarly journals STUDIES ON CELL METABOLISM AND CELL DIVISION

1940 ◽  
Vol 23 (4) ◽  
pp. 401-411 ◽  
Author(s):  
G. H. A. Clowes ◽  
M. E. Krahl
Keyword(s):  
Carbon Monoxide ◽  
Oxygen Consumption ◽  
Cell Division ◽  
Cell Metabolism ◽  
Potassium Cyanide ◽  
Iodoacetic Acid ◽  
Mass Action ◽  
Comparable Rate ◽  
Arbacia Punctulata ◽  
Rate Of Oxygen Consumption

1. The effects of a number of respiratory inhibiting agents on the cell division of fertilized eggs of Arbacia punctulata have been determined. For eggs initially exposed to the reagents at 30 minutes after fertilization at 20°C., the levels of oxygen consumption prevailing in the minimum concentrations of reagents which produced complete cleavage block were (as percentages of the control): In 0.4 per cent O2-99.6 per cent N2, 32; in 0.7 per cent O2-99.3 per cent CO, 32; in 1.6 x 10–4M potassium cyanide, 34; in 1 x 10–3M phenylurethane, 70; in 4 x 10–3M 5-isoamyl-5-ethyl barbituric acid, 20; in 3 x 10–4M iodoacetic acid, 53. 2. The carbon monoxide inhibition of oxygen consumption and cell division was reversed by light. The percentage inhibition of oxygen consumption by carbon monoxide in the dark is described by the usual mass action equation with K, the inhibition constant, equal to approximately 60, as compared to values of 5 to 10 for yeast and muscle. In 20 per cent O2-80 per cent CO in the dark there was a slight stimulation of oxygen consumption, averaging 20 per cent. 3. Spectroscopic examination of fertilized and unfertilized Arbacia eggs reduced by hydrosulfite revealed no cytochrome bands. The thickness and density of the egg suspension was such as to indicate that, if cytochrome is present at all, the amount in Arbacia eggs is extremely small as compared to that in other tissues having a comparable rate of oxygen consumption. 4. Three reagents poisoning copper catalyses, potassium dithio-oxalate (10–2M), diphenylthiocarbazone (10–4M), and isonitrosoacetophenone (2 x 10–3M) produced no inhibition of division of fertilized Arbacia eggs. 5. These results indicate that the respiratory processes required to support division in the Arbacia egg may perhaps differ in certain essential steps from the principal respiratory processes in yeast and muscle.

VARIOUS EFFECTS OF THYROXINE ANALOGUES ON THE HEART AND SERUM CHOLESTEROL IN THE RAT

1960 ◽  
Vol 21 (1) ◽  
pp. 25-32 ◽  
Author(s):  
G. S. BOYD ◽  
M. F. OLIVER
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Serum Cholesterol ◽  
Rate Ratio ◽  
Heart Weight ◽  
Liver Cholesterol ◽  
Response Curves ◽  
Experimental Conditions ◽  
Cholesterol Levels ◽  
Stimulation Of

SUMMARY A series of twelve iodinated thyroxine analogues was studied for thyro-activity in the rat. Each analogue produced antigoitrogenic activity, increased oxygen consumption, heart rate and heart weight, and decreased serum and liver cholesterol levels. A 'serum cholesterol/heart rate ratio' may be computed for these analogues under fixed experimental conditions. While the dose-response curves for different analogues in any of these assays are rarely parallel, it is, nevertheless, clear that under certain experimental conditions some iodothyronines cause a relatively greater depression of cholesterol levels and less stimulation of heart rate than others. Some of the most active in this respect are DT4, DT3, DT2 and T4F.

scholarly journals ON THE RATE OF OXYGEN CONSUMPTION BY FERTILIZED AND UNFERTILIZED EGGS

1931 ◽  
Vol 15 (2) ◽  
pp. 167-182 ◽  
Author(s):  
D. M. Whitaker
Keyword(s):  
Oxygen Consumption ◽  
Cell Division ◽  
Fucus Vesiculosus ◽  
High Rate ◽  
Rate Of Oxygen Consumption ◽  
C 50 ◽  
Very High

1. The unfertilized eggs of Fucus vesiculosus, in the dark, consume about 5.2 mm.3 O2 per hour per 10 mm.3 eggs. 2. With an illumination of 100,000 foot candles in photosynthesis they liberate more than twice as much oxygen as they consume. 3. The actively swimming antherozoids or sperm of Fucus consume oxygen at a very high rate: 25.5 mm.3 O2 per hour per 10 mm.3 antherozoids. 4. Immediately following fertilization, in the dark, the Fucus eggs increase the rate of oxygen consumption to about 190 per cent of the prefertilization rate. 5. This rate for fertilized eggs, about 190 per cent, is maintained uniformly for 13 or 14 hours, after which there is a barely perceptible rise until 24 hours (when measurements ceased). At 18°C. 50 per cent of the spores in a population have completed the first cell division about 15 hours after fertilization.

scholarly journals THE EFFECT OF PENICILLIN ON EGGS OF THE SEA URCHIN, ARBACIA PUNCTULATA

1945 ◽  
Vol 28 (5) ◽  
pp. 405-413 ◽  
Author(s):  
Richard J. Henry ◽  
Maryon D. Henry
Keyword(s):  
Oxygen Consumption ◽  
Cell Division ◽  
Sea Urchin ◽  
Inhibitory Action ◽  
Initial Concentration ◽  
Arbacia Punctulata ◽  
Sea Urchin Egg

1. Penicillin in the range of concentration from 250 U/ml. to approximately 2650 U/ml. inhibits the rate of cell division of the fertilized sea urchin egg from 0 to 100 per cent. 2. Penicillin in the same range of concentrations has no effect on the oxygen consumption of the unfertilized or the fertilized eggs. 3. Penicillin is bound by some component of the sea urchin egg in amounts sufficiently large to lower the initial concentration, this binding apparently not being related to the inhibitory action.

scholarly journals GLUCOSE-6-PHOSPHATE AND 6-PHOSPHOGLUCONATE DEHYDROGENASES FROM EGGS OF THE SEA URCHIN, ARBACIA PUNCTULATA

1955 ◽  
Vol 38 (4) ◽  
pp. 431-439 ◽  
Author(s):  
M. E. Krahl ◽  
A. K. Keltch ◽  
C. P. Walters ◽  
G. H. A. Clowes
Keyword(s):  
Oxygen Consumption ◽  
Dehydrogenase Activity ◽  
Sea Urchin ◽  
Maximal Activity ◽  
Glycolytic Pathway ◽  
Supernatant Fraction ◽  
Arbacia Punctulata ◽  
Rate Of Oxygen Consumption ◽  
Wet Weight ◽  
Glucose 6 Phosphate Dehydrogenase

1. Glucose-6-phosphate and 6-phosphogluconate dehydrogenases have been found in homogenates of Arbacia eggs; 95 per cent of the activity toward each substrate is recovered in the supernatant fraction after centrifuging at 20,000 g for 30 minutes. 2. With glucose-6-phosphate as substrate) the rate of TPN reduction by the supernatant fraction from 1 gm. wet weight unfertilized or fertilized eggs was 1.8 to 3.0 micromoles per minute; this rate is sufficient to support a rate of oxygen consumption 24 times that observed for unfertilized, and 6 times that for fertilized, eggs. Pentose was formed from glucose-6-phosphate at a rate 0.3 to 0.5 that of TPN reduction, when both rates were expressed as micromoles per minute. 3. The concentrations of glucose-6-phosphate and 6-phosphogluconate for half maximal activity were each approximately 0.00004 M for the respective enzymes in the supernatant fraction. Maximal activity toward 6-phosphogluconate was 50 to 60 per cent of that toward glucose-6-phosphate. Glucose-6-phosphate dehydrogenase activity was 50 per cent inhibited in presence of 0.00006 M 2,4,5-trichlorophenol. 4. Reduction of DPN by the supernatant fraction in presence of fructose-1,6-diphosphate and ADP was 0.1 to 0.2 micromoles per minute per gm. wet eggs, indicating that the glycolytic pathway can metabolize glucose-6-phosphate at about 5 per cent the rate at which it can be oxidized by the TPN system from unfertilized or fertilized Arbacia eggs. 5. Phosphoglucomutase, hexose isomerase, and a phosphatase for fructose-1,6-diphosphate also appear to be present in Arbacia eggs.

scholarly journals Oxygen dependence of respiration in rat spinotrapezius muscle in situ

2012 ◽  
Vol 303 (1) ◽  
pp. H47-H56 ◽  
Author(s):  
Aleksander S. Golub ◽  
Roland N. Pittman
Keyword(s):  
Oxygen Consumption ◽  
Metabolic Regulation ◽  
Oxygen Supply ◽  
Striated Muscle ◽  
Muscle Fibers ◽  
Experimental Conditions ◽  
Rate Of Oxygen Consumption ◽  
Disappearance Curve ◽  
Resting Muscle

The oxygen dependence of respiration in striated muscle in situ was studied by measuring the rate of decrease of interstitial Po2 [oxygen disappearance curve (ODC)] following rapid arrest of blood flow by pneumatic tissue compression, which ejected red blood cells from the muscle vessels and made the ODC independent from oxygen bound to hemoglobin. After the contribution of photo-consumption of oxygen by the method was evaluated and accounted for, the corrected ODCs were converted into the Po2 dependence of oxygen consumption, V̇o2, proportional to the rate of Po2 decrease. Fitting equations obtained from a model of heterogeneous intracellular Po2 were applied to recover the parameters describing respiration in muscle fibers, with a predicted sigmoidal shape for the dependence of V̇o2 on Po2. This curve consists of two regions connected by the point for critical Po2 of the cell (i.e., Po2 at the sarcolemma when the center of the cell becomes anoxic). The critical Po2 was below the Po2 for half-maximal respiratory rate ( P 50) for the cells. In six muscles at rest, the rate of oxygen consumption was 139 ± 6 nl O2/cm3·s and mitochondrial P 50 was k = 10.5 ± 0.8 mmHg. The range of Po2 values inside the muscle fibers was found to be 4–5 mmHg at the critical Po2. The oxygen dependence of respiration can be studied in thin muscles under different experimental conditions. In resting muscle, the critical Po2 was substantially lower than the interstitial Po2 of 53 ± 2 mmHg, a finding that indicates that V̇o2 under this circumstance is independent of oxygen supply and is discordant with the conventional hypothesis of metabolic regulation of the oxygen supply to tissue.

scholarly journals Stimulation of Oxygen Consumption with Fluid Absorption in Insect Recta

1982 ◽  
Vol 101 (1) ◽  
pp. 233-254
Author(s):  
D.F. HOULIHAN ◽  
D. SELL
Keyword(s):  
Oxygen Consumption ◽  
Time Course ◽  
Fluid Injection ◽  
Fluid Absorption ◽  
Fluid Uptake ◽  
Local Osmosis ◽  
Before And After ◽  
Rate Of Oxygen Consumption ◽  
Stimulation Of

The oxygen consumption of excised abdomens of cockroaches and locusts has been measured before and after the injection of fluids into the ligated recta. Fluid injection caused a transient stimulation of oxygen consumption of up to 30% of the resting rate. The extra amount of oxygen consumed is positively correlated with the osmolality of the fluid injected and the amount of fluid absorbed. Parallel experiments were carried out on the time course of fluid uptake; these experiments revealed a correlation first between a rapid increase in fluid absorption and stimulation of oxygen consumption, and secondly between the final resting rate of oxygen consumption and a slower absorption of fluid. Locusts take up fluid at double the rate of cockroaches and have double the stimulation in oxygen consumption following fluid injection. In locusts the increases in oxygen consumption can also be correlated with the net movement of Na+, K+and Cl− from the rectum. The stimulation of oxygen consumption during fluid uptake is discussed in relation to the local osmosis model for fluid uptake.

scholarly journals STUDIES ON CELL METABOLISM AND CELL DIVISION

1942 ◽  
Vol 25 (5) ◽  
pp. 733-747 ◽  
Author(s):  
M. E. Krahl ◽  
Bernhard J. Jandorf ◽  
G. H. A. Clowes
Keyword(s):  
Cell Division ◽  
Pyruvic Acid ◽  
Cell Metabolism ◽  
Thiamine Hydrochloride ◽  
Anaerobic Conditions ◽  
Arbacia Punctulata ◽  
Quantitative Extraction

1. Methods suitable for the determination of diphosphothiamine (cocarboxylase) in eggs of Arbacia punctulata have been developed. Quantitative extraction of the cocarboxylase was effected by combining the use of thiamine hydrochloride in the extraction fluid with critical adjustment of the pH of extraction to pH 6.3–6.7. 2. The unfertilized eggs were found to contain the equivalent of 2 to 3 micrograms of natural yeast cocarboxylase per gm. of wet eggs; the cocarboxylase content of the 30 minute and 10 hour fertilized eggs was somewhat less (Table III). 3. In preliminary experiments, Arbacia egg cytolysates were found to cause pyruvic acid to disappear. The rate of such disappearance was apparently greater under aerobic than under anaerobic conditions; it was also greater for cytolysates from fertilized eggs than for cytolysates from unfertilized eggs (Table IV).

scholarly journals The dissociation of exocytosis and respiratory stimulation in leucocytes by ionophores

1976 ◽  
Vol 156 (2) ◽  
pp. 209-213 ◽  
Author(s):  
G Zabucchi ◽  
D Romeo
Keyword(s):  
Oxygen Consumption ◽  
Lactate Dehydrogenase ◽  
Ionophore A23187 ◽  
Polymorphonuclear Leucocytes ◽  
Free Medium ◽  
Alkali Cations ◽  
Experimental Conditions ◽  
Bivalent Cations ◽  
Respiratory Stimulation ◽  
Stimulation Of

By exploiting the unique characteristics of three ionophores, experimental conditions were found which permit the dissociation of respiratory stimulation from secretion in polymorphonuclear leucocytes. A marked stimulation of respiration was produced by ionophore X537A, which binds and transports both alkali-earth and alkali cations. The stimulatory activity of this ionophore was the same at either high or low Na+/K+ ratios in the medium and was virtually unaffected by extracellular Ca2+. A slight stimulation of oxygen consumption was also caused by the K+-selective ionophore valinomycin and by ionophore A23187, which complexes and transfers bivalent cations. Ionophore X537A and valinomycin were unable to stimulate selective release of granuleassociated β-glucuronidase and gradually increased cell fragility, as monitored by increased leakage of lactate dehydrogenase. Ionophore A23187 slightly increased exocytosis of β-glucuronidase. In a Mg2+-free medium, Ca2+, added simultaneously with ionophore A23187, greatly enhanced respiration and secretion of the granule enzyme. If Ca2+ was added a few minutes after the ionophore, exocytosis occurred, but no respiratory burst was observed. If the latter experiment was repeated in the presence of extracellular Mg2+, both secretion and respiration were stimulated. This effect was not produced by Mn2+ or Ba2+. It is proposed that Ca2+ is required for triggering selective secretion of granule enzymes from leucocytes is caused by an intracellular redistribution of cations, which may invovle Mg2+-dependent mechanisms.

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