scholarly journals INTRACELLULAR DISTRIBUTION OF CALCIUM IN DEVELOPING BREAST MUSCLE OF NORMAL AND DYSTROPHIC CHICKENS

1964 ◽  
Vol 23 (2) ◽  
pp. 241-252 ◽  
Author(s):  
Ethel Cosmos
Keyword(s):  
Embryonic Development ◽  
Protein Metabolism ◽  
Microsomal Fraction ◽  
Calcium Content ◽  
Intracellular Distribution ◽  
Differential Centrifugation ◽  
Maximal Level ◽  
Complete Exchange ◽  
A New Technique ◽  
Muscle Calcium

To follow the intracellular distribution of calcium in the breast muscles of developing chickens, Ca45 was injected into the albumen of predeveloped eggs. Since the embryos were grown in a radioactive medium, a complete exchange of the isotope for its non-radioactive counterpart in muscles was accomplished. Subcellular particulates of the muscle cells were separated by the method of differential centrifugation. Analysis of the separated fractions showed that in the muscles of the 13-day embryo, when the nuclear-myofibrillar ratio is high, 65 per cent of the muscle calcium is in the nuclei. With the increased synthesis of myofibrils, the nuclear-myofibrillar ratio decreases with a concomitant fall in radioactivity. Thus, calcium was not associated with the developing myofibrils. At the time of hatching, when myofibrils perform physiological work, the highest level of calcium is in the mitochondria. This suggests that the mitochondria play a key role in the physiological activities of calcium in the cell. The microsomal fraction reaches a maximal level of calcium when the adult composition of muscle is attained. Results of investigations on dystrophic muscles show changes in the calcium distribution of the fractions as early as the 3rd week of embryonic development, which are interpreted to indicate an alteration in the protein metabolism of the cell, or an early destruction of muscle tissue. Further, alterations in the calcium content of fractions which seem to regulate the movements of this ion in the cell are discussed. A new technique for homogenizing tissues from embryos of different ages is presented.

Secretagogue-induced changes in subcellular Ca2+ distribution in isolated pancreatic acini

1981 ◽  
Vol 240 (2) ◽  
pp. G130-G140
Author(s):  
R. L. Dormer ◽  
J. A. Williams
Keyword(s):  
Atomic Absorption Spectrometry ◽  
High Speed ◽  
Microsomal Fraction ◽  
Absorption Spectrometry ◽  
Subcellular Fractionation ◽  
Differential Centrifugation ◽  
Zymogen Granules ◽  
Pancreatic Acini ◽  
Induced Changes ◽  
Stimulation Of

In a prior study, we demonstrated that pancreatic secretagogues increased both the uptake into and washout of 45Ca2+ from isolated mouse pancreatic acini. The net result of these processes was an initial fall in total acinar cell Ca2+ content. In the present study, we have employed subcellular fractionation of acini under conditions that minimized posthomogenization redistribution of Ca2+ in order to localize those organelles involved in intracellular Ca2+ fluxes. Homogenization and differential centrifugation of acini, preloaded with 45Ca2+ and subjected to a period of washout, showed that carbachol induced an increased loss of 45Ca2+ from all fractions isolated. The high-speed microsomal fraction lost 45Ca2+ to a greater extent than did whole acini; measurement of total Ca2+ by atomic absorption spectrometry showed a net loss of Ca2+ from this fraction. Purification of the lower-speed fractions indicated that carbachol increased 45Ca2+ exchange with both zymogen granules and mitochondria, but net Ca2+ levels in these organelles were unchanged. It was concluded that stimulation of pancreatic acini by carbachol results in the release of calcium from a microsomal compartment leading to a rise in cytoplasmic Ca2+, increased exchange with granule and mitochondrial Ca2+, and increased efflux of Ca2+ from the cell.

PHOSPHODIESTERASE AND ACID PHOSPHATASE ACTIVITIES OF AVIAN BONE MARROW CELLS

1965 ◽  
Vol 43 (8) ◽  
pp. 1319-1328 ◽  
Author(s):  
Gerald Kingsley Bristow ◽  
Esther W. Yamada
Keyword(s):  
Bone Marrow ◽  
Acid Phosphatase ◽  
Bone Marrow Cells ◽  
Intracellular Distribution ◽  
Specific Substrate ◽  
Magnesium Ions ◽  
Differential Centrifugation ◽  
Alkaline Ph ◽  
Ph Optimum ◽  
Rna And Dna

Avian bone marrow has been found to contain a phosphodiesterase as well as an acid phosphatase. Some properties of these enzymes have been described. Because the phosphodiesterase of this tissue has an alkaline pH optimum, is activated by magnesium ions, and acts on the specific substrate p-nitrophenyl thymidine 5′-phosphate, it is probably a phosphodiesterase I such as is present in snake venom and other tissues.The intracellular distribution of these two enzymes in normal and regenerating bone marrow was studied. Subcellular fractions were prepared by differential centrifugation or by centrifugation through sucrose density gradients. The RNA and DNA content of each fraction was determined. By the methods used no differences in the properties or intracellular distribution of the two enzymes in normal and regenerating bone marrow were found.

Effects of manganese on Q-T interval and distribution of calcium in rat heart

1963 ◽  
Vol 205 (6) ◽  
pp. 1209-1212 ◽  
Author(s):  
Loyal L. Conrad ◽  
Donald J. Baxter
Keyword(s):  
Rat Heart ◽  
Calcium Concentration ◽  
Microsomal Fraction ◽  
The Other ◽  
Heart Cell ◽  
Differential Centrifugation ◽  
Serum Calcium Concentration ◽  
Significant Prolongation ◽  
Normal Rat ◽  
Cell Fractions

Electrocardiographic observations were correlated with the 2- and 24-hr uptake of Ca45 by the myocardium of the normal rat and the rat injected subcutaneously with manganese chloride. The distribution of Ca45 in the heart cell was determined by differential centrifugation and the effects of manganese noted. Normally, about 40% of the Ca45 in the rat heart was found in the microsomal fraction, the remainder being distributed equally in the other cell fractions at 2 hr. None was found in the supernatant material after centrifuging for 17 hr. After manganese injection the total uptake of Ca45 was doubled at 2 hr due to increases in the microsomal and 17-hr fractions. Control values were re-established by 24 hr. Electrocardiograms showed a significant prolongation of the Q-T interval at 2 and 24 hr after manganese injection. There was a significant decrease in serum calcium concentration 24 hr after the injection of manganese.

scholarly journals Intracellular Distribution of 5' Nucleotidase in Rat Liver

1958 ◽  
Vol 4 (4) ◽  
pp. 373-376 ◽  
Author(s):  
Gaston de Lamirande ◽  
Claude Allard ◽  
Antonio Cantero
Keyword(s):  
Enzymatic Activity ◽  
Rat Liver ◽  
Biochemical Analysis ◽  
Inorganic Phosphorus ◽  
Intracellular Distribution ◽  
Differential Centrifugation ◽  
Nucleotidase Activity ◽  
Rat Liver Cells ◽  
Cell Fractions

The intracellular distribution of 5' nucleotidase was investigated in rat liver by biochemical analysis of cell fractions obtained by differential centrifugation. The enzymatic activity was measured by determination of the inorganic phosphorus liberated from 5' nucleotides. The 5' nucleotidase activity was mainly found in the nuclear and microsomal fractions. An attempt to extract the enzyme from these fractions with Mg++ ion solutions was unsuccessful. It is concluded that 5' nucleotidase is actually present in the nuclear and microsomal fractions of rat liver cells.

Anion-stimulated ATPase in locust rectal epithelium

1988 ◽  
Vol 66 (2) ◽  
pp. 431-438 ◽  
Author(s):  
R. A. Lechleitner ◽  
J. E. Phillips
Keyword(s):  
Alkaline Phosphatase ◽  
Plasma Membrane ◽  
Atpase Activity ◽  
Microsomal Fraction ◽  
Leucine Aminopeptidase ◽  
Mitochondrial Fraction ◽  
Mitochondrial Enzymes ◽  
Differential Centrifugation ◽  
Succinate Cytochrome C Reductase ◽  
Nacl Cotransport

The rectum, the main reabsorptive site in the locust excretory system, actively transports Cl−. This Cl− absorption is electrogenie, not dependent on Na+or [Formula: see text] and insensitive to inhibitors of NaCl cotransport or [Formula: see text] exchange. To determine if active Cl− transport across rectal epithelia might be due to an anion-stimulated ATPase, a microsomal fraction was obtained by differential centrifugation. Microsomal ATPase activity was stimulated in the following sequence: sulphite > bicarbonate > chloride. Maximal ATPase activity was obtained at 25 mM [Formula: see text] or 25 mM Cl−. Thiocyanate (10 mM) inhibited 90% of the anion-stimulated ATPase activity. The microsomal fraction was enriched in the plasma membrane markers, leucine aminopeptidase, alkaline phosphatase, 5′-nucleotidase, and γ-glutamyItranspeptidase, and had little contamination of the mitochondrial enzymes, succinate cytochrome c reductase and cytochrome oxidase. Na,K-ATPase was enriched in the mitochondrial fraction. Microscopic examination confirmed that basolateral membranes were associated with mitochondria following differential centrifugation, while the microsomal fraction contained little mitochondrial contamination. These results indicate the presence of an anion-stimulated ATPase activity that could be responsible for active Cl− transport across locust recta.

scholarly journals Parotid microsomal Ca2+ transport. Subcellular localization and characterization

1982 ◽  
Vol 208 (3) ◽  
pp. 789-794 ◽  
Author(s):  
P Kanagasuntheram ◽  
T S Teo
Keyword(s):  
Endoplasmic Reticulum ◽  
Parotid Gland ◽  
Subcellular Localization ◽  
Microsomal Fraction ◽  
Narrow Range ◽  
Differential Centrifugation ◽  
Linear Rate ◽  
Rat Parotid Gland ◽  
Rat Parotid ◽  
Nadph Cytochrome C Reductase

Rat parotid gland homogenates were fractionated into mitochondrial, heavy microsomal and light microsomal fractions by differential centrifugation. ATP-dependent 45Ca2+ uptake by the subcellular fractions paralleled the distribution of NADPH-cytochrome c reductase, an enzyme associated with the endoplasmic reticulum. The highest rate of Ca2+ uptake was found in the heavy microsomal fraction. Ca2+ uptake by this fraction was dependent on the presence of ATP and was sustained at a linear rate by 5 mM-oxalate. Inhibitors of mitochondrial Ca2+ transport had no effect on the rate of Ca2+ uptake. Na+ and K+ stimulated Ca2+ uptake. At optimal concentrations. Na+ stimulated Ca2+ uptake by 120% and K+ stimulated Ca2+ uptake by 260%. Decreasing the pH from 7.4 to 6.8 had little effect on Ca2+ uptake. The Km for Ca2+ uptake was 3.7 microM free Ca2+ and 0.19 mM-ATP. Vanadate inhibited Ca2+ uptake; 60 microM-vanadate inhibited the rate of Ca2+ accumulation by 50%. It is concluded that the ATP-dependent Ca2+ transport system is located on the endoplasmic reticulum and may play a role in maintaining intracellular levels of free Ca2+ within a narrow range of concentration.

scholarly journals Incorporation of [14C]glucosamine and [14C]leucine into mouse kidney β-glucuronidase induced by gonadotrophin

1970 ◽  
Vol 117 (1) ◽  
pp. 161-167 ◽  
Author(s):  
Keitaro Kato ◽  
Hiroyuki Ide ◽  
Tsuranobu Shirahama ◽  
William H. Fishman
Keyword(s):  
Endoplasmic Reticulum ◽  
Microsomal Fraction ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sucrose Density Gradient ◽  
Mouse Kidney ◽  
Differential Centrifugation ◽  
Freezing And Thawing ◽  
Sucrose Density Gradient Centrifugation ◽  
Glucuronidase Activity

Male BALB/C mice were injected intraperitoneally with 2.5 i.u. of gonadotrophin. After the injection, increase of β-glucuronidase activity was first observed in the microsomal fraction. By 36h 45–50% of the total homogenate activity was found in the microsomal fraction compared with 20–25% in the control microsomal fraction. From 36 to 80h not only microsomal β-glucuronidase but also lysosomal β-glucuronidase increased progressively. After 69h stimulation with 2.5 i.u. of gonadotrophin, d-[1-14C]glucosamine or l-[U-14C]leucine was injected intraperitoneally. After a further 3h the kidneys were homogenized and five particulate fractions were prepared by differential centrifugation. The β-glucuronidase in the microsomal and lysosomal fractions was released respectively by ultrasonication and by freezing and thawing treatment. The enzyme was purified by organic-solvent precipitation and by sucrose-density-gradient centrifugation. The results demonstrated the incorporation of these two labels into the mouse renal β-glucuronidase. The microsomal β-glucuronidase was much more radioactive than the lysosomal enzyme and approx. 80% of the newly synthesized enzyme appeared in microsomes and approx. 20% of that was found in lysosomes at this period. These results suggest that the mouse renal β-glucuronidase is a glycoprotein and that the newly synthesized enzyme is transported from endoplasmic reticulum to lysosomes.

scholarly journals ALTERATIONS IN BIOCHEMICAL COMPOSITION AND RIBONUCLEIC ACID METABOLISM INDUCED IN RAT LIVER BY CORTISONE

1956 ◽  
Vol 2 (3) ◽  
pp. 331-350 ◽  
Author(s):  
Charles Upton Lowe ◽  
Royden N. Rand
Keyword(s):  
Rat Liver ◽  
Biochemical Composition ◽  
Microsomal Fraction ◽  
Acid Metabolism ◽  
Chemical Constituents ◽  
Differential Centrifugation ◽  
Sucrose Solutions ◽  
The Relationship

An investigation of the effect of cortisone administration upon the chemical composition of intracellular particulates of rat liver has been made. Livers were homogenized in 0.25 M sucrose solutions and submitted to differential centrifugation. Five fractions were prepared: mitochondria (Mit), microsomes (Mi), ultracentrifugable (U), non-sedimentable (S), and nuclear (Nuc). Measurement was made of total and polymerized RNA, nitrogen, lipide P, and uptake of P32 by the RNA of each fraction. The following observations were made:— Cortisone administration caused a fall in concentration in all measured constituents except glycogen. On a per liver basis, however, total liver RNA was unchanged in amount; nitrogen content of Mi fell and that of S increased; the lipide P of Mit and Mi also decreased. The biochemical composition of a statistical mitochondrion was significantly altered; in contrast, the microsomal fraction decreased in amount, but the relationship between the chemical constituents was unchanged. When polymerized RNA was sought by a process involving precipitation from ethanol at 20°C., none was found in the Mit of cortisone livers and the amount in Mi was much less than found in the normal. When, however, precipitation was conducted at 4°C., yields of polymerized RNA in all fractions after cortisone were equal to or greater than those found in the normal. Furthermore, incubation of mixtures of homogenates from normal and cortisone livers resulted in loss of warm precipitable RNA. These data strongly suggest the presence of an enzyme in cortisone livers which upon incubation with normal livers made preparation of polymerized RNA virtually impossible by use of the warm method. This agent, thought to operate in vivo and in vitro, was not present in significant amounts in normal livers, since incubation in this instance had no effect upon the amount of polymerized RNA. Mit from cortisone livers obtained by the cold technique had a significantly decreased rate of incorporation of P32 even though the yield of RNA from this fraction was increased. To reconcile these observations, it was proposed that under the influence of cortisone a variant of normal RNA is synthesized or normal RNA is converted to this variant. This "new" RNA has new solubility properties, a new rate of incorporation of P32, and conceivably it cannot act as a template for normal protein synthesis.

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