Clathrin sheets on the protoplasmic surface of ventral membranes of osteoclasts in culture

2003 ◽  
Vol 52 (6) ◽  
pp. 535-543 ◽  
Author(s):  
T. Akisaka
Keyword(s):  
Protoplasmic Surface

scholarly journals THE KINETICS OF PENETRATION

1937 ◽  
Vol 20 (5) ◽  
pp. 737-766 ◽  
Author(s):  
A. G. Jacques
Keyword(s):  
Sea Water ◽  
Surface Layers ◽  
Marked Contrast ◽  
External Concentration ◽  
Protoplasmic Surface ◽  
Kinetics Of ◽  
External Ph

When 0.1 M NaI is added to the sea water surrounding Valonia iodide appears in the sap, presumably entering as NaI, KI, and HI. As the rate of entrance is not affected by changes in the external pH we conclude that the rate of entrance of HI is negligible in comparison with that of NaI, whose concentration is about 107 times that of HI (the entrance of KI may be neglected for reasons stated). This is in marked contrast with the behavior of sulfide which enters chiefly as H2S. It would seem that permeability to H2S is enormously greater than to Na2S. Similar considerations apply to CO2. In this respect the situation differs greatly from that found with iodide. NaI enters because its activity is greater outside than inside so that no energy need be supplied by the cell. The rate of entrance (i.e. the amount of iodide entering the sap in a given time) is proportional to the external concentration of iodide, or to the external product [N+]o [I-lo, after a certain external concentration of iodide has been reached. At lower concentrations the rate is relatively rapid. The reasons for this are discussed. The rate of passage of NaI through protoplasm is about a million times slower than through water. As the protoplasm is mostly water we may suppose that the delay is due chiefly to the non-aqueous protoplasmic surface layers. It would seem that these must be more than one molecule thick to bring this about. There is no great difference between the rate of entrance in the dark and in the light.

scholarly journals ACTION CURVES WITH SINGLE PEAKS IN NITELLA IN RELATION TO THE MOVEMENT OF POTASSIUM

1940 ◽  
Vol 23 (6) ◽  
pp. 743-748 ◽  
Author(s):  
W. J. V. Osterhout ◽  
S. E. Hill
Keyword(s):  
Outer Surface ◽  
Distilled Water ◽  
Protoplasmic Surface ◽  
Outer Protoplasmic Surface ◽  
Two Peaks

In Nitella the action curve has two peaks, apparently because both protoplasmic surfaces (inner and outer) are sensitive to K+. Leaching in distilled water makes the outer surface insensitive to K+. We may therefore expect the action curve to have only one peak. This expectation is realized. The action curve thus obtained resembles that of Chara which has an outer protoplasmic surface that is normally insensitive to K+. The facts indicate that the movement of K+ plays an important part in determining the shape of the action curve.

scholarly journals THE ROLE OF WATER IN PROTOPLASMIC PERMEABILITY AND IN ANTAGONISM

1956 ◽  
Vol 39 (6) ◽  
pp. 963-976 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Surface Layer ◽  
Water Content ◽  
Active Substance ◽  
External Medium ◽  
Surface Active Substance ◽  
Potassium Ions ◽  
Protoplasmic Surface ◽  
Outer Protoplasmic Surface ◽  
Aqueous Surface ◽  
Surface Active

The behavior of the cell depends to a large extent on the permeability of the outer non-aqueous surface layer of the protoplasm. This layer is immiscible with water but may be quite permeable to it. It seems possible that a reversible increase or decrease in permeability may be due to a corresponding increase or decrease in the water content of the non-aqueous surface layer. Irreversible increase in permeability need not be due primarily to increase in the water content of the surface layer but may be caused chiefly by changes in the protoplasm on which the surface layer rests. It may include desiccation, precipitation, and other alterations. An artificial cell is described in which the outer protoplasmic surface layer is represented by a layer of guaiacol on one side of which is a solution of KOH + KCl representing the external medium and on the other side is a solution of CO2 representing the protoplasm. The K+ unites with guaiacol and diffuses across to the artificial protoplasm where its concentration becomes higher than in the external solution. The guaiacol molecule thus acts as a carrier molecule which transports K+ from the external medium across the protoplasmic surface. The outer part of the protoplasm may contain relatively few potassium ions so that the outwardly directed potential at the outer protoplasmic surface may be small but the inner part of the protoplasm may contain more potassium ions. This may happen when potassium enters in combination with carrier molecules which do not completely dissociate until they reach the vacuole. Injury and recovery from injury may be studied by measuring the movements of water into and out of the cell. Metabolism by producing CO2 and other acids may lower the pH and cause local shrinkage of the protoplasm which may lead to protoplasmic motion. Antagonism between Na+ and Ca++ appears to be due to the fact that in solutions of NaCl the surface layer takes up an excessive amount of water and this may be prevented by the addition of suitable amounts of CaCl2. In Nitella the outer non-aqueous surface layer may be rendered irreversibly permeable by sharply bending the cell without permanent damage to the inner non-aqueous surface layer surrounding the vacuole. The formation of contractile vacuoles may be imitated in non-living systems. An extract of the sperm of the marine worm Nereis which contains a highly surface-active substance can cause the egg to divide. It seems possible that this substance may affect the surface layer of the egg and cause it to take up water. A surface-active substance has been found in all the seminal fluids examined including those of trout, rooster, bull, and man. Duponol which is highly surface-active causes the protoplasm of Spirogyra to take up water and finally dissolve but it can be restored to the gel state by treatment with Lugol solution (KI + I). The transition from gel to sol and back again can be repeated many times in succession. The behavior of water in the surface layer of the protoplasm presents important problems which deserve careful examination.

scholarly journals MECHANICAL RESTORATION OF IRRITABILITY AND OF THE POTASSIUM EFFECT

1935 ◽  
Vol 18 (5) ◽  
pp. 687-694 ◽  
Author(s):  
S. E. Hill ◽  
W. J. V. Osterhout
Keyword(s):  
Distilled Water ◽  
Action Current ◽  
Protoplasmic Surface ◽  
Normal Behavior ◽  
Inner Surface ◽  
Potassium Effect ◽  
Outer Protoplasmic Surface

Treatment of Nitella with distilled water apparently removes from the cell something which is responsible for the normal irritability and the potassium effect, (i.e. the large P.D. between a spot in contact with 0.01 M KCl and one in contact with 0.01 M NaCl). Presumably this substance (called R) is partially removed from the protoplasm by the distilled water. When this has happened a pinch which forces sap out into the protoplasm can restore its normal behavior. The treatment with distilled water which removes the potassium effect from the outer protoplasmic surface does not seem to affect the inner protoplasmic surface in the same way since the latter retains the outwardly directed potential which is apparently due to the potassium in the sap. But the inner surface appears to be affected in such fashion as to prevent the increase in its permeability which is necessary for the production of an action current. The pinch restores its normal behavior, presumably by forcing R from the sap into the protoplasm.

THE RELATION BETWEEN FROST RESISTANCE AND THE PHYSICAL STATE OF PROTOPLASM: II. THE PROTOPLASMIC SURFACE

1941 ◽  
Vol 19c (1) ◽  
pp. 9-20 ◽  
Author(s):  
D. Siminovitch ◽  
J. Levitt
Keyword(s):  
Refractive Index ◽  
Frost Resistance ◽  
Physical State ◽  
Surface Membrane ◽  
Protoplasmic Surface

Deplasmolysis injury, ductility of cytoplasmic strands, and the shape assumed by injected oil drops on deplasmolysis were investigated. The surface membrane of the protoplast of non-hardy cells stiffened when dehydrated osmotically. As a result, it ruptured readily when subjected to tension. The stiffening either failed to occur in hardy cells, or it arose only as a result of a much greater dehydration (depending on the degree of hardiness). The refractive index of the protoplasmic surface increased more on dehydration in the case of non-hardy than of hardy cells. Plasmolysis, if maintained for some time, induced a clumping of plastids and granules (systrophy) in non-hardy but not in hardy cells. All these facts indicate a greater hydrophily in hardy than in non-hardy cells—both of the surface membrane of the protoplasm and, as shown in Part I, of the protoplasm as a whole, although it is probably less marked in the latter.

scholarly journals CHANGES OF APPARENT IONIC MOBILITIES IN PROTOPLASM

1936 ◽  
Vol 20 (1) ◽  
pp. 13-43 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Sea Water ◽  
Chemical Compounds ◽  
Monomolecular Layer ◽  
Normal Cells ◽  
Protein Film ◽  
Organic Ions ◽  
Protoplasmic Surface ◽  
Short Latent Period ◽  
Ionic Mobilities ◽  
Cell Changes

In normal cells of Valonia the order of the apparent mobilities of the ions in the non-aqueous protoplasmic surface is K > Cl > Na. After treatment with 0.01 M guaiacol (which does not injure the cell) the order becomes Na > Cl > K. As it does not seem probable that such a reversal could occur with simple ions we may assume provisionally that in the protoplasmic surface we have to do with charged complexes of the type (KXI)+, (KXII)+, where XI and XII are elements or radicals, or with chemical compounds formed in the protoplasm. When 0.01 M guaiacol is added to sea water or to 0.6 M NaCl (both at pH 6.4, where the concentration of the guaiacol ion is negligible) the P.D. of the cell changes (after a short latent period) from about 10 mv. negative to about 28 mv. positive and then slowly returns approximately to its original value (Fig. 1, p. 14). This appears to depend chiefly on changes in the apparent mobilities of organic ions in the protoplasm. The protoplasmic surface is capable of so much change that it does not seem probable that it is a monomolecular layer. It does not behave like a collodion nor a protein film since the apparent mobility of Na+ can increase while that of K+ is decreasing under the influence of guaiacol.

scholarly journals STUDIES OF THE INNER AND OUTER PROTOPLASMIC SURFACES OF LARGE PLANT CELLS

1943 ◽  
Vol 27 (2) ◽  
pp. 139-142 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Osmotic Pressure ◽  
Outer Surface ◽  
Plant Cells ◽  
Central Vacuole ◽  
Electrical Measurements ◽  
Surface Layers ◽  
Large Plant ◽  
Protoplasmic Surface

In Nitella, Chara, Hydrodictyon, and Valonia the inner and outer non-aqueous protoplasmic surface layers can be separated by certain plasmolytic agents which penetrate the outer surface more rapidly than the inner and hence raise the osmotic pressure of the protoplasm lying between them and cause it to increase in thickness by taking up water from the central vacuole. We may therefore conclude that the two surfaces differ. This idea is confirmed by earlier electrical measurements which show that when sap is placed outside the cell the chain See PDF for Structure produces an E.M.F. of several millivolts.

scholarly journals DIFFERING RATES OF DEATH AT INNER AND OUTER SURFACES OF THE PROTOPLASM

1944 ◽  
Vol 28 (1) ◽  
pp. 23-36 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Hydrostatic Pressure ◽  
Partition Coefficient ◽  
The Other ◽  
Protoplasmic Surface ◽  
Inner Surface ◽  
Potassium Effect ◽  
Outer Protoplasmic Surface ◽  
The Difference

When protoplasm dies it becomes completely and irreversibly permeable and this may be used as a criterion of death. On this basis we may say that when 0.2 M formaldehyde plus 0.001 M NaCl is applied to Nitella death arrives sooner at the inner protoplasmic surface than at the outer. If, however, we apply 0.17 M formaldehyde plus 0.01 M KCl death arrives sooner at the outer protoplasmic surface. The difference appears to be due largely to the conditions at the two surfaces. With 0.2 M formaldehyde plus 0.001 M NaCl the inner surface is subject to a greater electrical pressure than the outer and is in contact with a higher concentration of KCl. In the other case these conditions are more nearly equal so that the layer first reached by the reagent is the first to become permeable. The outer protoplasmic surface has the ability to distinguish electrically between K+ and Na+ (potassium effect). Under the influence of formaldehyde this ability is lost. This is chiefly due to a falling off in the partition coefficient of KCl in the outer protoplasmic surface. At about the same time the inner protoplasmic surface becomes completely permeable. But the outer protoplasmic surface retains its ability to distinguish electrically between different concentrations of the same salt, showing that it has not become completely permeable. After the potential has disappeared the turgidity (hydrostatic pressure inside the cell) persists for some time, probably because the outer protoplasmic surface has not become completely permeable.

scholarly journals THE MECHANISM OF ACCUMULATION IN LIVING CELLS

1952 ◽  
Vol 35 (4) ◽  
pp. 579-594 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Osmotic Pressure ◽  
Outer Surface ◽  
Organic Molecules ◽  
Sea Water ◽  
Relative Rate ◽  
Point Of View ◽  
External Concentration ◽  
Protoplasmic Surface ◽  
A Cell ◽  
Outer Protoplasmic Surface

When a compound enters a living cell until its activity becomes greater inside than outside, it may be said to accumulate. Since it moves from a region where its activity is relatively low to a region where its activity is relatively high, it is evident that work must be done to bring this about. The following explanation is suggested to account for accumulation. The protoplasmic surface is covered with a non-aqueous layer which is permeable to molecules but almost impermeable to ions. Hence free ions cannot enter except in very small numbers. The experiments indicate that ions combine at the outer surface with organic molecules (carrier molecules) and are thus able to enter freely. If upon reaching the aqueous protoplasm these molecules are decomposed or altered so as to set the ions free, the ions must be trapped since they cannot pass out except in very small numbers. If we adopt this point of view we can suggest answers to some important questions. Among these are the following: 1. Why accumulation is confined to electrolytes. This is evident since only ions will be trapped. 2. Why ions appear to penetrate against a gradient. Actually there is no such penetration since the ions enter in combination with molecules. The energy needed to raise the activity of entering compounds is furnished by the reactions involved in the process of accumulation. 3. Why, in absence of injury, ions do not come out when the cell is placed in distilled water. Presumably the outgoing ions will combine at the outer surface with carrier molecules and then move inward in the same way as ions coming from without. 4. Why the relative rate of penetration falls off as the external concentration increases. This is because the entrance of ions is limited by the number of carrier molecules but no such limitation exists when ions move outward since they can do so without combining with carrier molecules. 5. Why accumulation is promoted by constructive metabolism which is needed to build up the organic molecules and by destructive metabolism which brings about their decomposition. 6. Why measuring the mobilities of ions in the outer protoplasmic surface does not enable us to predict the relative rate of entrance of ions. We find for example in Nitella that K+ has a much higher mobility than Na+ but the accumulation of these ions does not differ greatly. This is to be expected if they enter by combining with molecules at the surface. Only if K+ is able to combine preferentially will it accumulate preferentially. 7. Why ions may come out in anoxia and at low temperatures. If these conditions depress the formation of carrier molecules and their decomposition in the protoplasm, the balance between intake and outgo of ions will be disturbed and relatively more may come out. 8. Why the excess of internal over external osmotic pressure is less in sea water than in fresh water. As the external concentration of ions increases the rate of intake does not increase in direct proportion since the number of carrier molecules does not increase and this slows down the relative rate of intake of ions. But it does not slow down the rate of exit of ions since they need not combine with carrier molecules in order to pass out. Hence the excess of ions inside will be relatively less as the concentration of external ions increases. 9. How water is pumped from solutions of higher to solutions of lower osmotic pressure. If metabolism and consequently accumulation is higher at one end of a cell than at the other, the internal osmotic pressure will be higher at the more active end and this makes it possible for the cell to pump water from solutions of higher osmotic pressure at the more active end to solutions of lower osmotic pressure at the less active, as shown experimentally for Nitella. This might help to explain the action of kidney cells and the production of root pressure in plants.

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