scholarly journals THE SELECTIVE ABSORPTION OF POTASSIUM BY ANIMAL CELLS

1921 ◽  
Vol 4 (2) ◽  
pp. 141-148 ◽  
Author(s):  
Philip H. Mitchell ◽  
J. Walter Wilson ◽  
Ralph E. Stanton
Keyword(s):  
Electronic Structure ◽  
Cesium Chloride ◽  
Ringer Solution ◽  
Living Cells ◽  
Selective Absorption ◽  
Physiological Effects ◽  
Equivalent Amount ◽  
Animal Cells ◽  
Relationship Of ◽  
Resting Muscle

1. Frog muscles perfused with Ringer solution in which potassium chloride has been replaced by an equivalent amount of rubidium or cesium chloride take up rubidium or cesium and incorporate them into the tissue substance in such form as to be retained during a subsequent perfusion with potassium-free Ringer solution, provided the muscles contract during the first perfusion. Retention of rubidium or cesium by a resting muscle does not occur. 2. Rats on synthetic diets, adequate in all respects except that potassium was replaced by an equivalent amount of rubidium or cesium, died after a period varying from 10 to 17 days with characteristic symptoms including tetanic spasms. Muscle, heart, liver, kidney, spleen, and lung tissues were then found to contain significant amounts of rubidium or cesium. The concentration of these metals in the muscle amounted, in some cases, as shown by a spectroscopic estimation, to about half the concentration of potassium normally found in mammallian muscle. 3. The results are regarded as tending to confirm the theory that the peculiarities in the physiological effects of potassium, including the facility with which it is "selected" by living cells in preference to sodium, are related to the electronic structure of the potassium ion as compared with that of similar ions. The possible relationship of the comparative migration velocity, a function of the electronic structure, to physiological effects is suggested.

scholarly journals THE SELECTIVE ABSORPTION OF POTASSIUM BY ANIMAL CELLS

1921 ◽  
Vol 4 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Philip H. Mitchell ◽  
J. Walter Wilson
Keyword(s):  
Ringer Solution ◽  
Potassium Content ◽  
Selective Absorption ◽  
Free Medium ◽  
Animal Cells ◽  
Contracting Muscle ◽  
Individual Variations

1. Individual variations in the potassium content of the fresh muscles of frogs are notable even when computed as percentages of the dry solids. The potassium content averaged higher in freshly collected summer frogs than in winter frogs after a period of captivity. 2. Muscles show a loss of from 8 to 15 per cent of their potassium during perfusion with potassium-free Ringer solution but tenaciously hold the remainder. 3. Muscles, stimulated to contract under conditions that do not produce irreversible stages of fatigue, show losses of potassium no greater than those attributable to the presence of a potassium-free medium. 4. A condition favorable to the taking up of potassium probably occurs in a contracting muscle because rubidium and cesium, substances very similar to potassium in chemical and physiological behavior, are absorbed in retainable form by a contracting muscle but not by a resting one.

Bulk-surface relationship of an electronic structure for high-throughput screening of metal oxide catalysts

2016 ◽  
Vol 370 ◽  
pp. 279-290 ◽  
Author(s):  
Joshua Minwoo Kweun ◽  
Chenzhe Li ◽  
Yongping Zheng ◽  
Maenghyo Cho ◽  
Yoon Young Kim ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Metal Oxide ◽  
High Throughput ◽  
High Throughput Screening ◽  
Oxide Catalysts ◽  
Metal Oxide Catalysts ◽  
Bulk Surface ◽  
Relationship Of

scholarly journals SIMILARITY OF THE KINETICS OF INVERTASE ACTION IN VIVO AND IN VITRO. II

1932 ◽  
Vol 16 (2) ◽  
pp. 233-242 ◽  
Author(s):  
B. G. Wilkes ◽  
Elizabeth T. Palmer
Keyword(s):  
Physiological Activity ◽  
Outer Region ◽  
Living Cells ◽  
Yeast Cells ◽  
Live Cells ◽  
Intracellular Enzyme ◽  
Relationship Of ◽  
Kinetics Of

1. The pH-activity relationship of invertase has been studied in vivo and in vitro under identical external environmental conditions. 2. The effect of changing (H+) upon the sucroclastic activity of living cells of S. cerevisiae and of invertase solutions obtained therefrom has been found, within experimental error, to be identical. 3. The region of living yeast cells in which invertase exerts its physiological activity changes its pH freely and to the same extent as that of the suspending medium. It is suggested that this may indicate that this intracellular enzyme may perform its work somewhere in the outer region of the cell. 4. In using live cells containing maltase, no evidence of increased sucroclastic activity around pH 6.9, due to the action of Weidenhagen's α-glucosidase (maltase), was found.

Isolated flagellar apparatus of Chlamydomonas: characterization of forward swimming and alteration of waveform and reversal of motion by calcium ions in vitro

1978 ◽  
Vol 33 (1) ◽  
pp. 235-253 ◽  
Author(s):  
J.S. Hyams ◽  
G.G. Borisy
Keyword(s):  
Calcium Ions ◽  
Beat Frequency ◽  
Flagellar Apparatus ◽  
Adenosine Monophosphate ◽  
Adenosine Diphosphate ◽  
Living Cells ◽  
Exogenous Calcium ◽  
Ph Range ◽  
Relationship Of

The control of flagellar activity in the biflagellate green alga, Chlamydomonas reinhardtii was investigated by the in vitro reactivation of the isolated flagellar apparatus (the 2 flagella attached to their respective basal bodies plus accessory structures). The waveform and beat frequency of the isolated apparatus in the presence of 1 mM adenosine triphophate (ATP) were comparable to those recorded for living cells. Equimolar concentrations of adenosine diphosphate (ADP) could be substituted for ATP with little change in beat frequency and no apparent change in waveform, suggesting that the latter is converted to ATP by axonemal adenylate kinase. No reactivation occurred in adenosine monophosphate (AMP). But frequencies in cytidine, guanosine and uridine triphosphates (CTP, GTP and UTP) were approximately 10% that obtained in ATP. Reactivation was optimal over a broad pH range between pH 6.4 and pH 8.9 in both APT and ADP. Isolated flagellar apparatus could be induced to change from forward to reverse motion in vitro by manipulation of exogenous calcium ions. The 2 types of motion were directly comparable to recorded responses of living cells. Forward swimming occurred at levels of calcium below 10(−6)M, the isolated apparatus changing to backward motion above this level. Motility was inhibited at concentrations above 10(−3)M. The threshold for reversal of motion by calcium was lowered to 10(−7)M when the flagellar membranes were solubilized with detergent, indicating that the flagellar membranes are involved in the regulaion of the level of calcium within the axoneme. The reversal of motion by calcium was itself freely reversible. The relationship of these observations to the known tactic responses of Chlamydomonas is discussed.

scholarly journals QUANTITATIVE RELATIONSHIP OF ELECTRONIC STRUCTURE AND INHIBITION ACTIVITY OF CURCUMIN ANALOGS ON ETHOXYRESORUFIN o-DEALKYLATION (EROD) REACTION

2010 ◽  
Vol 7 (1) ◽  
pp. 78-82
Author(s):  
Harno Dwi Pranowo ◽  
Iqmal Tahir ◽  
Ajidarma Widiatmoko
Keyword(s):  
Electronic Structure ◽  
Statistical Parameter ◽  
Quantitative Relationship ◽  
Equation Model ◽  
Semiempirical Methods ◽  
Inhibition Activity ◽  
Net Charge ◽  
Curcumin Analogs ◽  
Leave One Out ◽  
Relationship Of

Electronic structure and inhibition activity relationship study of curcumin analogs has been established for 29 curcumin analogs on Ethoxyresorufin O-Dealkylation (EROD) reaction using atomic net charge descriptor based on AM1 semiempirical calculations. The QSAR (Quantitative Structure and Activities Relationships) equation model was determined by statistical parameter from multiple regression analysis and leave-one-out cross validation method. The best QSAR equation was described:   Keywords: curcumin, QSAR, descriptor, atomic net charge, semiempirical methods.

Relationship of depolarization to phosphorus metabolism and transport in excitable tissues

1964 ◽  
Vol 207 (6) ◽  
pp. 1435-1440 ◽  
Author(s):  
L. G. Abood ◽  
I. Koyama ◽  
Virginia Thomas
Keyword(s):  
Ganglion Cells ◽  
Ringer Solution ◽  
Resting Potential ◽  
Spinal Ganglia ◽  
Potassium Ions ◽  
Transport Mechanisms ◽  
High Concentration ◽  
High K ◽  
Spinal Ganglion Cells ◽  
Relationship Of

In the presence of Ringer solution containing a high concentration of potassium ions, the incorporation of orthophosphate-P32 into ATP and other organophosphates of the desheathed sciatic nerve or spinal ganglia of bullfrog was inhibited over 75%. The inhibition in calcium-free Ringer solution containing EDTA was somewhat less. With increasing external K+ there was a good correlation between the decrease in the resting potential of spinal ganglion cells and the inhibition of P32 incorporation into ATP and phosphocreatine. Since oxidative phosphorylation or carbohydrate metabolism was not inhibited by high K+, it was concluded that the K+ interfered with the transport mechanisms involved in orthophosphate-P32 exchange across the nerve membrane. Pi transport was believed to involve the following three chain-linked reactions: 1) carrier + P ⇌ carrier P; 2) carrier P ⇌ carrier + Pi; 3) Pi + ADP ⇌ ATP, where the first two reactions occurred in the membrane and the third within mitochondria. Reaction I or II was presumed to be K+ sensitive. The possible mechanisms involved in such an inhibition are discussed in terms of present-day theories relating to bioelectric phenomena.

scholarly journals Microtubule dynamics and chromosome motion visualized in living anaphase cells.

1988 ◽  
Vol 106 (4) ◽  
pp. 1185-1192 ◽  
Author(s):  
G J Gorbsky ◽  
P J Sammak ◽  
G G Borisy
Keyword(s):  
Chromosome Segregation ◽  
Digital Imaging ◽  
Living Cells ◽  
Microtubule Dynamics ◽  
Chromosome Movement ◽  
Animal Cells ◽  
Digital Imaging Microscopy ◽  
Opposite Pole ◽  
Anaphase B ◽  
Chromosome Motion

Chromosome segregation in most animal cells is brought about through two events: the movement of the chromosomes to the poles (anaphase A) and the movement of the poles away from each other (anaphase B). Essential to an understanding of the mechanism of mitosis is information on the relative movements of components of the spindle and identification of sites of subunit loss from shortening microtubules. Through use of tubulin derivatized with X-rhodamine, photobleaching, and digital imaging microscopy of living cells, we directly determined the relative movements of poles, chromosomes, and a marked domain on kinetochore fibers during anaphase. During chromosome movement and pole-pole separation, the marked domain did not move significantly with respect to the near pole. Therefore, the kinetochore microtubules were shortened by the loss of subunits at the kinetochore, although a small amount of subunit loss elsewhere was not excluded. In anaphase A, chromosomes moved on kinetochore microtubules that remained stationary with respect to the near pole. In anaphase B, the kinetochore fiber microtubules accompanied the near pole in its movement away from the opposite pole. These results eliminate models of anaphase in which microtubules are thought to be traction elements that are drawn to and depolymerized at the pole. Our results are compatible with models of anaphase in which the kinetochore fiber microtubules remain anchored at the pole and in which microtubule dynamics are centered at the kinetochore.

Atom the Electronic Structure and Atomic Extranuclear Movement State of Research

2012 ◽  
Vol 554-556 ◽  
pp. 374-378 ◽  
Author(s):  
Li Wei Wang
Keyword(s):  
Electronic Structure ◽  
Atomic Nucleus ◽  
Rotation Frequency ◽  
Light Quantum ◽  
Quantum Hypothesis ◽  
Atomic Spectra ◽  
Quantum Nature ◽  
State Of Research ◽  
Relationship Of ◽  
The Relationship

Based on the Planck's quantum hypothesis and the Einstein's light quantum hypothesis , the Zhongjizi (a new elementary particles) hypothesis is proposed. It revealed the quantum nature of light. Light quantum (which is photon) was essentially a collection of Zhongjizi, light was constituted of Zhongjizi, the essence of light was the nature of particle, and the quantum nature of light was essentially the Zhongjizi nature of light. The quantum nature of light revealed out: atomic spectra was produced by the light of different frequencies that emitted and absorbed by the extranuclear electrons of different motion states (different rotation frequencies) under certain conditions. The rotation frequency of extranuclear electrons was equal to the frequencies of light that emitted and absorbed by the electrons. By using this law, and according to the atomic spectra, we can know the state of the electron structure of atoms and the movement of electrons ,according to the frequency (the cycle )that rotate round the nuclear of the extranuclear electron in a state of motion , and the relationship of the distance between the electrons and the atomic nucleus .

scholarly journals The Role of the Cell Integrity Pathway in Septum Assembly in Yeast

2021 ◽  
Vol 7 (9) ◽  
pp. 729
Author(s):  
Cesar Roncero ◽  
Rubén Celador ◽  
Noelia Sánchez ◽  
Patricia García ◽  
Yolanda Sánchez
Keyword(s):  
Cell Wall ◽  
Map Kinases ◽  
Signalling Pathways ◽  
Cell Integrity ◽  
Animal Cells ◽  
Yeast Saccharomyces Cerevisiae ◽  
Downstream Effectors ◽  
Cell Wall Integrity Pathway ◽  
Extracellular Matrix Remodelling ◽  
Relationship Of

Cytokinesis divides a mother cell into two daughter cells at the end of each cell cycle and proceeds via the assembly and constriction of a contractile actomyosin ring (CAR). Ring constriction promotes division furrow ingression, after sister chromatids are segregated to opposing sides of the cleavage plane. Cytokinesis contributes to genome integrity because the cells that fail to complete cytokinesis often reduplicate their chromosomes. While in animal cells, the last steps of cytokinesis involve extracellular matrix remodelling and mid-body abscission, in yeast, CAR constriction is coupled to the synthesis of a polysaccharide septum. To preserve cell integrity during cytokinesis, fungal cells remodel their cell wall through signalling pathways that connect receptors to downstream effectors, initiating a cascade of biological signals. One of the best-studied signalling pathways is the cell wall integrity pathway (CWI) of the budding yeast Saccharomyces cerevisiae and its counterpart in the fission yeast Schizosaccharomyces pombe, the cell integrity pathway (CIP). Both are signal transduction pathways relying upon a cascade of MAP kinases. However, despite strong similarities in the assembly of the septa in both yeasts, there are significant mechanistic differences, including the relationship of this process with the cell integrity signalling pathways.

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