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

1944 ◽  
Vol 28 (1) ◽  
pp. 17-22 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Plant Cells ◽  
Good Deal ◽  
Neutral Red ◽  
Central Vacuole ◽  
Normal Position ◽  
Brilliant Cresyl Blue ◽  
Large Plant ◽  
Cresyl Blue ◽  
Mechanical Disturbance ◽  
Outer Protoplasmic Surface

The vacuolar surface of Nitella is covered with a non-aqueous film too thin to be visible as a separate membrane. The motion of the protoplasm may subject this film to a good deal of mechanical disturbance. Apparently this does not rupture the film for no dye escapes into the protoplasm as the result of such disturbance when the vacuolar sap is deeply stained with neutral red or brilliant cresyl blue. When the deeply stained central vacuole breaks up into several smaller vacuoles, leaving the outer protoplasmic surface in its normal position, there is no evidence of the escape of dye into the protoplasm through the film surrounding the vacuole.

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.

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.

The absorption of electrolytes in large plant cells

1936 ◽  
Vol 2 (6) ◽  
pp. 283-315 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Plant Cells ◽  
Large Plant

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.

Numerical investigation of shear-flow free-surface turbulence and air entrainment at large Froude and Weber numbers

2019 ◽  
Vol 880 ◽  
pp. 209-238 ◽  
Author(s):  
Xiangming Yu ◽  
Kelli Hendrickson ◽  
Bryce K. Campbell ◽  
Dick K. P. Yue
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Shear Flow ◽  
Power Law ◽  
Outer Surface ◽  
Air Entrainment ◽  
Entrainment Rate ◽  
Surface Layers ◽  
Surface Turbulence ◽  
Free Surface Turbulence

We investigate two-phase free-surface turbulence (FST) associated with an underlying shear flow under the condition of strong turbulence (SFST) characterized by large Froude ($Fr$) and Weber ($We$) numbers. We perform direct numerical simulations of three-dimensional viscous flows with air and water phases. In contrast to weak FST (WFST) with small free-surface distortions and anisotropic underlying turbulence with distinct inner/outer surface layers, we find SFST to be characterized by large surface deformation and breaking accompanied by substantial air entrainment. The interface inner/outer surface layers disappear under SFST, resulting in nearly isotropic turbulence with ${\sim}k^{-5/3}$ scaling of turbulence kinetic energy near the interface (where $k$ is wavenumber). The SFST air entrainment is observed to occur over a range of scales following a power law of slope $-10/3$. We derive this using a simple energy argument. The bubble size spectrum in the volume follows this power law (and slope) initially, but deviates from this in time due to a combination of ongoing broad-scale entrainment and bubble fragmentation by turbulence. For varying $Fr$ and $We$, we find that air entrainment is suppressed below critical values $Fr_{cr}$ and $We_{cr}$. When $Fr^{2}>Fr_{cr}^{2}$ and $We>We_{cr}$, the entrainment rate scales as $Fr^{2}$ when gravity dominates surface tension in the bubble formation process, while the entrainment rate scales linearly with $We$ when surface tension dominates.

Trafficking of Phosphatidylinositol 3-Phosphate from the trans-Golgi Network to the Lumen of the Central Vacuole in Plant Cells

2001 ◽  
Vol 13 (2) ◽  
pp. 287 ◽  
Author(s):  
Dae Heon Kim ◽  
Young-Jae Eu ◽  
Cheol Min Yoo ◽  
Yong-Woo Kim ◽  
Kyeong Tae Pih ◽  
...  
Keyword(s):  
Plant Cells ◽  
Central Vacuole ◽  
Trans Golgi Network ◽  
Golgi Network ◽  
Phosphatidylinositol 3

Spin-glass-like freezing of inner and outer surface layers in hollow Fe2O3 nanoparticles

2017 ◽  
Author(s):  
H. Khurshid ◽  
P. Lampen-Kelley ◽  
O. Iglesias ◽  
J. Alonso ◽  
M. Phan ◽  
...  
Keyword(s):  
Spin Glass ◽  
Outer Surface ◽  
Surface Layers
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