scholarly journals THE KINETICS OF PENETRATION

1938 ◽  
Vol 22 (2) ◽  
pp. 147-163 ◽  
Author(s):  
A. G. Jacques
Keyword(s):  
Osmotic Pressure ◽  
Free Space ◽  
Partition Coefficients ◽  
Sea Water ◽  
Intact Cell ◽  
Linear Part ◽  
Osmotic Concentration ◽  
Intact Cells ◽  
Rate Of Increase ◽  
Kinetics Of

When Valonia cells are impaled on capillaries, it is in some ways equivalent to removing the comparatively inelastic cellulose wall. Under these conditions sap can migrate into a free space and it is found that on the average the rate of increase of volume of the sap is 15 times what it is in intact cells kept under comparable conditions. The rate of increase of volume is a little faster during the first few hours of the experiment, but it soon becomes approximately linear and remains so as long as the experiment is continued. The slightly faster rate at first may mean that the osmotic pressure of the sap is approaching that of the sea water (in the intact cell the sap osmotic pressure is always slightly above that of the sea water). This might result from a more rapid entrance of water than of electrolyte, as would be expected when the restriction of the cellulose wall was removed. During the linear part of the curve the osmotic concentration and the composition of the sap suffer no change, so that entrance of electrolyte must be 15 times as fast in the impaled cells as it is in the intact cells. The explanation which best accords with the facts is that in the intact cell the entrance of electrolyte tends to increase the osmotic pressure. As a consequence the protoplasm is partially dehydrated temporarily and it cannot take up more water until the cellulose wall grows so that it can enclose more volume. The dehydration of the protoplasm may have the effect of making the non-aqueous protoplasm less permeable to electrolytes by reducing the diffusion and partition coefficients on which the rate of entrance depends. In this way the cell is protected against great fluctuations in the osmotic concentration of the sap.

scholarly journals THE KINETICS OF PENETRATION

1939 ◽  
Vol 22 (6) ◽  
pp. 757-773 ◽  
Author(s):  
A. G. Jacques
Keyword(s):  
Natural Variation ◽  
Sea Water ◽  
Intact Cell ◽  
The State ◽  
Osmotic Concentration ◽  
Linear Rate ◽  
Partial Dissipation ◽  
Rate Of Increase ◽  
The Difference ◽  
Kinetics Of

When cells of Halicystis are impaled on a capillary so that space is provided into which the sap can migrate, the rate of entrance of water and of electrolyte is increased about 10-fold. In impaled Valonia cells the rate is increased about 15-fold. After a relatively rapid non-linear rate of increase of sap volume immediately after impalement (which may possibly represent the partial dissipation of the difference of the osmotic energy between intact and impaled cells) the volume increases at a linear rate, apparently indefinitely. Since the halide concentration of the sap at the end of the experiment is (within the limits of natural variation) the same as in the intact cell, we conclude that electrolyte also enters the sap about 10 times as fast as in the intact cell. As in the case of Valonia we conclude that there is a mechanism whereby in the intact cell the osmotic concentration of the sap is prevented from greatly exceeding that of the sea water. This may be associated with the state of hydration of the non-aqueous protoplasmic surfaces.

The effect of external salinity on drinking rate and rectal secretion in the larvae of the saline-water mosquito Aedes taeniorhynchus

1977 ◽  
Vol 66 (1) ◽  
pp. 97-110
Author(s):  
T. J. Bradley ◽  
J. E. Phillips
Keyword(s):  
Sea Water ◽  
External Medium ◽  
Narrow Range ◽  
Saline Water ◽  
Fluid Secretion ◽  
Osmotic Concentration ◽  
Drinking Rate ◽  
Aedes Taeniorhynchus ◽  
External Salinity ◽  
Kinetics Of

1. The drinking rate of the saline-water mosquito larva Aedes taeniorhyncus (100 nl.mg-1.h-1) is unaffected by the salinity of the external medium, but is directly proportional to the surface area of the animal. 2. Haemolymph Na+, Mg2+, K+, Cl-, SO42- and osmotic concentrations were measured in larvae adapted to 10%, 100% and 200% seawater and were found to be regulated within a narrow range. 3. With the exception of potassium, ionic concentrations in rectal secretion were found to increase with increasing concentrations of the sea water in which larvae were reared. 4. The osmotic concentration of rectal secretion was unaffected by changes in haemolymph osmotic concentration but did rise when sodium or chloride concentrations of the haemolymph were increased. High levels of these ions also stimulated the rate of fluid secretion. 5. Transport of chloride and sodium by the rectum exhibits the kinetics of allosteric rather than classical enzymes.

scholarly journals KINETICS OF THE SWELLING OF CELLS AND TISSUES

1927 ◽  
Vol 11 (1) ◽  
pp. 43-56 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Sea Water ◽  
Distilled Water ◽  
Rate Of Increase ◽  
Kinetics Of

The rate of swelling of Arbacia eggs in dilute sea water, studied by Lillie and by Lucke and McCutcheon, may be expressed by the formulæ derived for the rate of increase in volume of a solution enclosed in a collodion sac. The rate of swelling of slices of carrot in distilled water, measured by Stiles and Jørgensen, may be expressed by the equation derived previously for the swelling of similarly shaped blocks of gelatin.

scholarly journals GROWTH AND LABILITY OF CHAETOPTERUS OOCYTE MITOTIC SPINDLES ISOLATED IN THE PRESENCE OF PORCINE BRAIN TUBULIN

1974 ◽  
Vol 62 (1) ◽  
pp. 175-184 ◽  
Author(s):  
Shinya Inoué ◽  
Gary G. Borisy ◽  
Daniel P. Kiehart
Keyword(s):  
Intact Cell ◽  
Cell Lysis ◽  
Meiotic Metaphase ◽  
Mitotic Spindles ◽  
Temperature Dependent ◽  
Intact Cells ◽  
Pig Brain ◽  
Transient Rise ◽  
Kinetics Of ◽  
Brain Tubulin

Purified tubulin solutions stabilized and augmented the birefringence (BR) of isolated Chaetopterus spindles. Tubulin was extracted from pig brain tissue in cold PEG buffer (0.1 M piperazine-N-N'-bis[2-ethane sulfonic acid], 1 mM ethylene bis-[oxyethylenenitrilo]tetraacetate, [EGTA], 2.5 mM guanosine triphosphate, [GTP], pH 6.94, at 25°C), and purified by two cycles of a reversible, temperature-dependent assembly-disassembly procedure. The spindle BR of the meiotic metaphase-arrested oocytes of Chaetopterus decreased linearly at a rate of 1.5 nm/min when perfused with PEG buffer without tubulin. In this hypotonic, calcium-chelating solution, the cell lysed within 1.5 min, and after a brief, transient rise, the BR disappeared in ca. 4 min from the time of buffer application. Cells perfused with tubulin in PEG buffer also showed BR decay at the same rate until cell lysis. Immediately upon cell lysis the spindle BR increased, initially at ca. 2.3 nm/min and then more slowly until the BR attained or exceeded intact cell values. Spindle and asters grew considerably larger than those in intact cells. From the kinetics of the transient BR increase after lysis, we infer that, initially, Chaetopterus cytoplasmic tubulin contributes to increased BR; further augmentation required added pig brain tubulin and most probably reflects the addition and incorporation of heterologous porcine tubulin into the spindle and asters. Isolated, augmented spindles depolymerized rapidly at 6°C. Upon return to 23°C, spindle BR returned slowly in tubulin-PEG. The BR of the isolates also decayed in solutions containing calcium ions 2.5 mM in excess of the EGTA. However, the isolates did not respond, or responded very slowly, to 1 mM colchicine or Colcemid and to dilution of tubulin with PEG solution. Microinjection into Chaetopterus oocytes of tubulin-PEG, but not PEG alone, enhanced spindle and aster BR which reversibly disappeared upon chilling the cell.

scholarly journals Effects of cyclic GMP on the kinetics of the photocurrent in rods and in detached rod outer segments.

1987 ◽  
Vol 90 (4) ◽  
pp. 527-551 ◽  
Author(s):  
S Hestrin ◽  
J I Korenbrot
Keyword(s):  
Cyclic Gmp ◽  
Outer Segment ◽  
Time Course ◽  
Intact Cell ◽  
Light Sensitivity ◽  
Biochemical Properties ◽  
Intact Cells ◽  
Outer Segments ◽  
High Concentrations ◽  
Kinetics Of

We investigated the effects of high concentrations of cytoplasmic cyclic GMP on the photocurrent kinetics and light sensitivity of the tiger salamander rod both in intact cells and in detached outer segments. Photoreceptors were internally perfused with cGMP by applying patch pipettes containing cGMP to the inner or outer segment. Large increases in the concentration of cGMP in the outer segment cytoplasm were achieved only when the patch pipette was applied directly to the outer segment. The dark-current amplitude increased with increasing cGMP concentrations up to approximately 1,400 pA. Internal perfusion with 5.0 mM cGMP introduced a delay of 1-3 s in the photocurrent. The magnitude of the delay was inversely proportional to the light intensity. In addition, the photocurrent time course was slowed down and the light sensitivity, measured 1 s after the flash, was decreased approximately 100-fold when compared with that of the intact cell. The observed effects of cGMP were compared with those predicted by a model that assumes that the initial photocurrent time course is determined by the kinetics of the light-activated phosphodiesterase (PDE) and the cGMP dependence of the light-sensitive channels. At high concentrations of cGMP, the experimental data were similar to those predicted by the model and based on the known biochemical properties of the light-activated PDE and cGMP-activated channels.

Interphase distribution of 2-furylethylenes

1985 ◽  
Vol 50 (8) ◽  
pp. 1642-1647 ◽  
Author(s):  
Štefan Baláž ◽  
Anton Kuchár ◽  
Ernest Šturdík ◽  
Michal Rosenberg ◽  
Ladislav Štibrányi ◽  
...  
Keyword(s):  
Partition Coefficient ◽  
Partition Coefficients ◽  
Transport Rate ◽  
Phase System ◽  
Two Phase ◽  
Interphase Distribution ◽  
Distribution Kinetics ◽  
System 1 ◽  
Kinetics Of

The distribution kinetics of 35 2-furylethylene derivatives in two-phase system 1-octanol-water was investigated. The transport rate parameters in direction water-1-octanol (l1) and backwards (l2) are partition coefficient P = l1/l2 dependent according to equations l1 = logP - log(βP + 1) + const., l2 = -log(βP + 1) + const., const. = -5.600, β = 0.261. Importance of this finding for assesment of distribution of compounds under investigation in biosystems and also the suitability of the presented method for determination of partition coefficients are discussed.

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 THE KINETICS OF EXOSMOSIS OF WATER FROM LIVING CELLS

1927 ◽  
Vol 10 (5) ◽  
pp. 659-664 ◽  
Author(s):  
Morton McCutcheon ◽  
Baldwin Lucke
Keyword(s):  
Osmotic Pressure ◽  
Salt Concentration ◽  
Driving Force ◽  
Temperature Characteristic ◽  
Living Cells ◽  
Velocity Constant ◽  
Osmotic Equilibrium ◽  
Kinetics Of

1. The rate of exosmosis of water was studied in unfertilized Arbacia eggs, in order to bring out possible differences between the kinetics of exosmosis and endosmosis. 2. Exosmosis, like endosmosis, is found to follow the equation See PDF for Equation, in which a is the total volume of water that will leave the cell before osmotic equilibrium is attained, x is the volume that has already left the cell at time t, and k is the velocity constant. 3. The velocity constants of the two processes are equal, provided the salt concentration of the medium is the same. 4. The temperature characteristic of exosmosis, as of endomosis, is high. 5. It is concluded that the kinetics of exosmosis and endosmosis of water in these cells are identical, the only difference in the processes being in the direction of the driving force of osmotic pressure.

scholarly journals Membrane-permeable luciferin esters for assay of firefly luciferase in live intact cells

1991 ◽  
Vol 276 (3) ◽  
pp. 637-641 ◽  
Author(s):  
F F Craig ◽  
A C Simmonds ◽  
D Watmore ◽  
F McCapra ◽  
M R H White
Keyword(s):  
Escherichia Coli ◽  
Mammalian Cells ◽  
Firefly Luciferase ◽  
Luciferase Expression ◽  
Intact Cells ◽  
Cos Cells ◽  
Escherichia Coli Cells ◽  
Luminescent Signal ◽  
The Difference ◽  
Kinetics Of

Five esters of luciferin were synthesized and compared with native luciferin as substrates for firefly luciferase expressed in live intact mammalian cells. The esters themselves were not substrates for purified luciferase, but four were substrates for a purified esterase and all appeared to be hydrolysed to luciferin within mammalian cells. At a substrate concentration of 0.01 mM, the peak luminescence from the cos cells expressing luciferase was up to 6-fold greater with the esters than with unmodified luciferin. At 0.1 mM, the difference between luciferin and the esters was decreased. The kinetics of the luminescent signal with the different luciferin esters varied significantly, indicating possible differences in the rates of uptake, breakdown and enzyme inhibition. The esters did not support luminescence from Escherichia coli cells expressing firefly luciferase, suggesting a lack of appropriate esterase activity in this particular strain. The esters could be useful for the assay of luciferase expression in intact mammalian cells when luciferin levels are limiting, for example in tissues, and in plants. Alternative luciferin derivatives may allow further improvements in sensitivity.

scholarly journals Extracellular accumulation of proline, serine and trehalose in the haemolymph of osmoconforming brackish-water mosquitoes

1987 ◽  
Vol 129 (1) ◽  
pp. 231-238 ◽  
Author(s):  
M. A. Garrett ◽  
T. J. Bradley
Keyword(s):  
Organic Compounds ◽  
Brackish Water ◽  
Sea Water ◽  
Full Range ◽  
Culex Tarsalis ◽  
Osmotic Concentration

Larvae of Culex tarsalis, a mosquito, are capable of surviving and developing in dilutions of sea water ranging from 0 mosmol l-1 to 700 mosmol l-1. In waters more dilute than 400 mosmol l-1, the larvae osmoregulate, whereas in those more concentrated than 400 mosmol l-1, the osmotic strength of the haemolymph parallels that of the medium, i.e. the larvae osmoconform. Over the full range of external concentrations tested, the larvae regulate the levels of Na+, K+, Mg2+, Ca2+ and Cl- in the haemolymph. Analyses of haemolymph samples from larvae adapted to media of 50 mosmol l-1 or 600 mosmol l-1 indicate that the increase in haemolymph osmotic concentration observed in media above 400 mosmol l-1 is due to the accumulation of organic compounds, particularly proline, serine and trehalose.

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