共查询到20条相似文献,搜索用时 15 毫秒
1.
Y. Y. Komissarchik E. S. Snigirevskaya E. I. Shakhmatova Y. V. Natochin 《Cell and tissue research》1998,293(3):517-524
Electron and confocal microscopy, using immunocytochemical methods, was employed to assess osmotic water permeability of the frog (Rana temporaria) urinary bladder during transcellular water transport, induced by antidiuretic hormone (ADH) or by wash-out of autacoids from serosal, ADH-free Ringer solution. The increase of osmotic water permeability of the urinary bladder was accompanied by relevant ultrastructural changes, the most remarkable being: (1) the appearance of aggregates of intramembranous particles in the apical membrane of granular cells, and the extent of the membrane area covered by the aggregates proportional to that of the water flow; (2) redistribution of actin filaments in the cytoplasm of granular cells; judging from the anti-actin label density, the number of actin filaments in the apical region of cytoplasm was reduced by 2.5–4 times compared with normal; (3) a decrease in the total electron density of the cytoplasm due to the increased water content of granular cells. 相似文献
2.
Fungi need water for all stages of life. Notably, mushrooms consist of ∼90% water. Fungi degrade organic matter by secreting enzymes. These enzymes need water to be able to break down the substrate. For instance, when the substrate is too dry, fungi transport water from moist areas to arid areas by hydraulic redistribution. Once nutrients are freed from the substrate, they are taken up by transporters lining the cell membrane. Thereby an intracellular osmotic potential is created which is greater than that of the substrate, and water follows by osmosis. Aquaporins may facilitate water uptake depending on the conditions. Since fungi possess a cell wall, the cell volume will not increase much by water uptake, but the cell membrane will exert higher pressure on the cell wall, thereby building up turgor. Fungi have tightly coordinated osmotic regulatory controls via the HOG pathway. When water is getting scarce, this pathway makes sure that enough osmolytes are synthesized to allow sufficient water uptake for maintaining turgor homeostasis. The fungal network is interconnected and allows water flow when small pressure differences exist. These pressure differences can be the result of growth, differential osmolyte uptake/synthesis or external osmotic conditions. Overall, the water potential of the substrate and of fungal tissues determine whether water will flow, since water flows from an area of high- to a low water potential area, when unobstructed. In this review we aim to give a comprehensive view on how fungi obtain and translocate water needed for their development. We have taken Agaricus bisporus growing on compost and casing soil as a case study, to discuss water relations during fruiting in detail. Using the current state-of-the-art we found that there is a discrepancy between the models describing water transport to mushrooms and the story that water potentials tell us. 相似文献
3.
《Cryobiology》2018
Several factors have been proposed to influence the red blood cell storage lesion including storage duration, blood component manufacturing methodology, and donor characteristics [1,18]. The objectives of this study were to determine the impact of manufacturing method and donor characteristics on water permeability and membrane quality parameters.Red blood cell units were obtained from volunteer blood donors and grouped according to the manufacturing method and donor characteristics of sex and age. Membrane water permeability and membrane quality parameters, including deformability, hemolysis, osmotic fragility, hematologic indices, supernatant potassium, and supernatant sodium, were determined on day 5 ± 2, day 21, and day 42. Regression analysis was applied to evaluate the contribution of storage duration, manufacturing method, and donor characteristics on storage lesion.This study found that units processed using a whole blood filtration manufacturing method exhibited significantly higher membrane water permeability throughout storage compared to units manufactured using red cell filtration. Additionally, significant differences in hemolysis, supernatant potassium, and supernatant sodium were seen between manufacturing methods, however there were no significance differences between donor age and sex groups.Findings of this study suggest that the membrane-related storage lesion is initiated prior to the first day of storage with contributions by both blood manufacturing process and donor variability. The findings of this work highlight the importance of characterizing membrane water permeability during storage as it can be a predictor of the biophysical and chemical changes that affect the quality of stored red blood cells during hypothermic storage. 相似文献
4.
MEMBRANE CHARACTERISTICS AND OSMOTIC BEHAVIOR OF ISOLATED ROD OUTER SEGMENTS 总被引:9,自引:3,他引:6
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Freshly isolated frog rod outer segments are sensitive osmometers which retain their photosensitivity; their osmotic behavior reveals essentially the same light-sensitive Na+ influx observed electrophysiologically in the intact receptor cell. Using appropriate osmotic conditions we have examined freeze-etch replicas of freshly isolated outer segments to identify the membrane which regulates the flow of water and ions. Under isosmotic conditions we find that the disc to disc repeat distance is almost exactly twice the thickness of a disc. This ratio appears to be the same in a variety of vertebrate rod outer segments and can be reliably measured in freeze-etch images. Under all our osmotic conditions the discs appear nearly collapsed. However, when the length of the outer segment is reduced by hyperosmotic shocks the discs move closer together. This markedly reduces the ratio of repeat distance to disc thickness since disc thickness remains essentially constant. Thus, the length reduction of isolated outer segments after hyperosmotic shocks primarily results from reduction of the extradisc volume. Since the discs are free floating and since they undergo negligibly small changes in volume, the plasma membrane alone must be primarily responsible for regulating the water flux and the light-sensitive Na+ influx in freshly isolated outer segments. On this basis we calculate, from the osmotic behavior, that the plasma membrane of frog rod outer segment has a Na+ permeability constant of about 2.8 x 10-6 cm/s and an osmotic permeability coefficient of greater than 2 x 10-3 cm/s. 相似文献
5.
6.
《Cryobiology》2017
Water transport across the red blood cell (RBC) membrane is an essential cell function that needs to be preserved during ex vivo storage. Progressive biochemical depletion during storage can result in significant conformational and compositional changes to the membrane. Characterizing the changes to RBC water permeability can help in evaluating the quality of stored blood products and aid in the development of improved methods for the cryopreservation of red blood cells. This study aimed to characterize the water permeability (Lp), osmotically inactive fraction (b), and Arrhenius activation energy (Ea) at defined storage time-points throughout storage and to correlate the observed results with other in vitro RBC quality parameters. RBCs were collected from age- and sex-matched blood donors. A stopped flow spectrophotometer was used to determine Lp and b by monitoring changes in hemoglobin autofluorescence when RBCs were exposed to anisotonic solutions. Experimental values of Lp were characterized at three different temperatures (4, 20 and 37 °C) to determine the Ea. Results showed that Lp, b, and Ea of stored RBCs significantly increase by day 21 of storage. Degradation of the RBC membrane with length of storage was seen as an increase in hemolysis and supernatant potassium, and a decrease in deformability, mean corpuscular hemoglobin concentration and supernatant sodium. RBC osmotic characteristics were shown to change with storage and correlate with changes in RBC membrane quality metrics. Monitoring water parameters is a predictor of membrane damage and loss of membrane integrity in ex vivo stored RBCs. 相似文献
7.
This paper reviews the passive mechanisms involved in the response of a yeast to changes in medium concentration and osmotic pressure. The results presented here were collected in our laboratory during the last decade and are experimentally based on the measurement of cell volume variations in response to changes in the medium composition. In the presence of isoosmotic concentration gradients of solutes between intracellular and extracellular media, mass transfers were found to be governed by the diffusion rate of the solutes through the cell membrane and were achieved within a few seconds. In the presence of osmotic gradients, mass transfers mainly consisting in a water flow were found to be rate limited by the mixing systems used to generate a change in the medium osmotic pressure. The use of ultra-rapid mixing systems allowed us to show that yeast cells respond to osmotic upshifts within a few milliseconds and to determine a very high hydraulic permeability for yeast membrane (Lp>6.10(-11) m x sec)-1) x Pa(-1)). This value suggested that yeast membrane may contain facilitators for water transfers between intra and extracellular media, i.e. aquaporins. Cell volume variation in response to osmotic gradients was only observed for osmotic gradients that exceeded the cell turgor pressure and the maximum cell volume decrease, observed during an hyperosmotic stress, corresponded to 60% of the initial yeast volume. These results showed that yeast membrane is highly permeable to water and that an important fraction of the intracellular content was rapidly transferred between intracellular and extracellular media in order to restore water balance after hyperosmotic stresses. Mechanisms implied in cell death resulting from these stresses are then discussed. 相似文献
8.
E I Shakhmatova 《Physiologia Bohemoslovaca》1988,37(1):91-94
With an increased influx of Ca2+ in the cytoplasm, the response of cells to ADH in the urinary bladder of the frog was lowered by addition of ionophore A23187 from the side of the basolateral cell membrane, but inhibited when it was added from the apical cell membrane. The removal of calcium by EGTA from the serosal surface was accompanied by a sharp increase of osmotic permeability not only to water, but also to inulin; while when calcium was removed from the mucosal surface of the urinary bladder, osmotic permeability was not changed. After being added to the Ringer solution from the outer surface of the apical cell membrane, the inhibitors of Ca2+ channels (verapamil, Ni2+, Mn2+, Co2+) decreased the effect of ADH. These data indicate that Ca2+ applied onto the outer surface of apical plasma membrane plays an important role in the action of ADH. 相似文献
9.
I Vlodavsky P E Fielding L K Johnson D Gospodarowicz 《Journal of cellular physiology》1979,100(3):481-495
Binding of either low density lipoprotein (LDL) or Concanavalin A (ConA) to actively growing vascular endothelial cells is associated with a redistrubution of the appropriate cell surface receptor sites which form patches and caps. This receptor lateral mobility is greatly restricted when endothelial cells reach confluence and adopt the configuration of a cell monolayer composed of closely apposed and non-overlapping cells. In this case, although the cells still exhibit specific LDL binding to the appropriate cell surface receptor sites, neither the binding of LDL nor of ConA induces a receptor redistribution. The lack of LDL receptor redistribution correlates with a marked decrease in the rate of LDL internalization. In contrast, no such density-dependent changes are observed in cell types which grow on top of each other and form multiple cell layers at confluence. Thus, neither LDL nor ConA induced cap formation in either sparse or confluent smooth muscle cell cultures and the same rate of LDL internalization is observed at both cell densities. Similarly, adsorptive endocytosis of cationized LDL (which enters the cells independently of the LDL receptor sites) was not correlated with a detectable receptor redistribution, nor was it significantly affected by changes in cell density and spatial organization. The formation of a confluent cell monolayer resting on an underlying basement membrane might therefore provide, via a change in membrane dynamics, a mechanism whereby the endothelium of large blood vessels can function as a protective barrier against the high circulating levels of LDL in plasma. 相似文献
10.
Cell volume kinetics of adherent epithelial cells measured by laser scanning reflection microscopy: determination of water permeability changes of renal principal cells 总被引:3,自引:0,他引:3
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The water channel aquaporin-2 (AQP2), a key component of the antidiuretic machinery in the kidney, is rapidly regulated by the antidiuretic hormone vasopressin. The hormone exerts its action by inducing a translocation of AQP2 from intracellular vesicles to the cell membrane. This step requires the elevation of intracellular cyclic AMP. We describe here a new method, laser scanning reflection microscopy (LSRM), suitable for determining cellular osmotic water permeability coefficient changes in primary cultured inner medullary collecting duct (IMCD) cells. The recording of vertical-reflection-mode x-z-scan section areas of unstained, living IMCD cells proved useful and valid for the investigation of osmotic water permeability changes. The time-dependent increases of reflection-mode x-z-scan section areas of swelling cells were fitted to a single-exponential equation. The analysis of the time constants of these processes indicates a twofold increase in osmotic water permeability of IMCD cells after treatment of the cells both with forskolin, a cyclic AMP-elevating agent, and with Clostridium difficile toxin B, an inhibitor of Rho proteins that leads to depolymerization of F-actin-containing stress fibers. This indicates that both agents lead to the functional insertion of AQP2 into the cell membrane. Thus, we have established a new functional assay for the study of the regulation of the water permeability at the cellular level. 相似文献
11.
Microtubules are needed for the perinuclear positioning of aquaporin-2 after its endocytic retrieval in renal principal cells 总被引:4,自引:0,他引:4
Vossenkämper A Nedvetsky PI Wiesner B Furkert J Rosenthal W Klussmann E 《American journal of physiology. Cell physiology》2007,293(3):C1129-C1138
Water reabsorption in the renal collecting duct is regulated by arginine vasopressin (AVP). AVP induces the insertion of the water channel aquaporin-2 (AQP2) into the plasma membrane of principal cells, thereby increasing the osmotic water permeability. The redistribution of AQP2 to the plasma membrane is a cAMP-dependent process and thus a paradigm for cAMP-controlled exocytic processes. Using primary cultured rat inner medullary collecting duct cells, we show that the redistribution of AQP2 to the plasma membrane is accompanied by the reorganization of microtubules and the redistribution of the small GTPase Rab11. In resting cells, AQP2 is colocalized with Rab11 perinuclearly. AVP induced the redistribution of AQP2 to the plasma membrane and of Rab11 to the cell periphery. The redistribution of both proteins was increased when microtubules were depolymerized by nocodazole. In addition, the depolymerization of microtubules prevented the perinuclear positioning of AQP2 and Rab11 in resting cells, which was restored if nocodazole was washed out and microtubules repolymerized. After internalization of AQP2, induced by removal of AVP, forskolin triggered the AQP2 redistribution to the plasma membrane even if microtubules were depolymerized and without the previous positioning of AQP2 in the perinuclear recycling compartment. Collectively, the data indicate that microtubule-dependent transport of AQP2 is predominantly responsible for trafficking and localization of AQP2 inside the cell after its internalization but not for the exocytic transport of the water channel. We also demonstrate that cAMP-signaling regulates the localization of Rab11-positive recycling endosomes in renal principal cells. dynein; Rab11 相似文献
12.
Water flow and water storage in Agave deserti: osmotic implications of crassulacean acid metabolism 总被引:5,自引:4,他引:1
Abstract Water flow and water storage were investigated for Agave deserti, a desert succulent showing crassulacean acid metabolism (CAM). The anatomy and water relations of the peripheral chlorenchyma, where CAM occurs, and the central water-storage parenchyma were investigated for its massive leaves so that these tissues could be incorporated as discrete elements into an electrical-circuit analogue of the whole plant. The daily cycling of osmotic pressure was represented by voltage sources in series with the storage capacitors. With soil water potential and leaf transpiration rate as input variables, axial water flow through the vascular bundles and radial flows into and out of storage during the day/night cycle were determined. The predominantly nocturnal transpiration was coincident with increases in cell osmotic pressure and in titratable acid of the leaf chlorenchyma. In the outer layers of the chlorenchyma, water potential was most negative at the beginning of the night when transpiration was maximum, while the water-storage parenchyma reached its minimal water potential 9 h later. The roots plus stem contributed 7% and the leaves contributed 50% to the total water flow during maximal transpiration; peak water flow from the soil to the roots occurred at dawn and was only 58% of the maximal transpiration rate. Over each 24-h period, 39% of the water lost from the plant was derived from storage, with flow into storage occurring mainly during the daytime. Simulations showed that the acid accumulation rhythm of CAM had little impact on water uptake from the soil under the conditions employed. In the outer chlorenchyma, water potential and water flows were more sensitive to the day/night changes in transpiration than in osmotic pressure. Nevertheless, cell osmotic pressure had a large influence on turgor pressure in this tissue and determined the extent to which storage was recharged during the latter part of the night. 相似文献
13.
利用12057单体及其二体连续两年进行抗旱生理招标的比较,结果表明:12057单体系珉春二体在灌浆中期旗叶相对含水量、细胞膜稳定性、叶片渗透势以及渗透调节能力等均存在差异。其中2B、3B、6B单体相对含水量较高;5A单体叶组织膜稳定性较高;4B、5B、4D、6B、3A单体的渗透势较低;6B、4B、3B、4D、、B单体的渗透调节能力较高。此外看出部分同源染色体群对上述生理招标的反应具有相似性。 相似文献
14.
BACKGROUND: Membrane potential changes in cells from the human lymphoid B cell line, JY, evoked by increasing cell density in culture were investigated, as data published on other cell types are controversial. An attempt was also made to clear the underlying mechanism. METHODS: Nonadherent JY cells were isolated from high-density plateau-phase cultures (type A cells), medium-density log-phase cultures (type B cells), and low-density lag-phase cultures (type C cells). They were analyzed for transmembrane potential, intracellular free concentration of potassium and sodium, membrane permeability for monovalent cations, cell cycle distribution by measuring DNA content, and glucose uptake. RESULTS: C type cells proved to be relatively depolarized (-41 +/- 3 mV) and cells obtained from the highest density cultures hyperpolarized (-60 +/- 3 mV). Intracellular concentrations ([K](i) = 92-97 mM and [Na](i) = 34-35 mM) were almost identical for each type of cell. The sodium/potassium permeability constant ratio in the A and C type of cells was 0.047 and 0.094, respectively. High-density culture conditions resulted in a pronounced G(1)-phase arrest. CONCLUSIONS: Differences in the membrane potential values induced by high-density culture conditions were maintained by changes in the membrane permeability for the monovalent cations. 相似文献
15.
《Experimental mycology》1984,8(4):283-297
Maturation of the cap ofCoprinus cinereus is accompanied by a specific pattern of changes in enzyme activities and metabolite levels. The most significant changes result in amplification of activity in the tricar☐ylic acid cycle and the urea cycle, as judged from the observation that succinate dehydrogenase, NADP-linked glutamate dehydrogenase, glutamine synthetase, ornithine acetyltransferase, and ornithine carbamyltransferase are elevated to levels in excess (in some cases greatly in excess) of those found in the stipe, while activity of the enzyme urease is absent from the cap though present in both stipe and mycelium. Regulation of NADP-glutamate dehydrogenase depends on a circuit involving accumulation of acetyl-CoA in tissues where ammonia is limiting. This enzyme, together with glutamine synthetase, probably contributes to an ammonium scavenging system. The net result of the shift in metabolism is accumulation of urea, and probably other nitrogenous metabolites, as osmotic solutes which drive water into the cells of the gill hymenium. This leads to inflation of these cells and their expansion can account for the changes in form through which the cap progresses as maturation proceeds. The system exemplifies different sorts of regulation, from substrate level to the gene level, and is an ideal model for study of the causative events that give rise to metabolic shifts which direct differentiation processes. 相似文献
16.
Water storage and osmotic pressure influences on the water relations of a dicotyledonous desert succulent 总被引:3,自引:1,他引:2
Abstract Water storage and nocturnal increases in osmotic pressure affect the water relations of the desert succulent Ferocactus acanthodes, which was studied using an electrical circuit analog based on the anatomy and morphology of a representative individual. Transpiration rates and osmotic pressures over a 24-h period were used as input variables. The model predicted water potential, turgor pressure and water flow for various tissues. Plant capacitances, storage resistances and nocturnal increases in osmotic pressure were varied to determine their role in the water relations of this dicotyledonous succulent. Water coming from storage tissues contributed about one-third of the water transpired at night: the majority of this water came from the nonphotosynthetic, water storage parenchyma of the stem. Time lags of 4 h were predicted between maximum transpiration and maximum water uptake from the soil. Varying the capacitance of the plant caused proportional changes in osmotically driven water movement but changes in storage resistance had only minor effects. Turgor pressure in the chlorenchyma depended on osmotic pressure, but was fairly insensitive to doubling or halving of the capacitance or storage resistance of the plant. Water uptake from the soil was only slightly affected by osmotic pressure changes in the chlorenchyma. For this stem succulent, the movement of water from the chlorenchyma to the xylem and the internal redistribution of water among stem tissues were dominated by nocturnal changes in chlorenchyma osmotic pressure, not by transpiration. 相似文献
17.
Ohinata A Nagai K Nomura J Hashimoto K Hisatsune A Miyata T Isohama Y 《Biochemical and biophysical research communications》2005,326(3):521-526
Aquaporin-5 (AQP5), a major water channel in lung epithelial cells, plays an important role in maintaining water homeostasis in the lungs. Cell surface expression of AQP5 is regulated by not only mRNA and protein synthesis but also changes in subcellular distribution. We investigated the effect of lipopolysaccharide (LPS) on the subcellular distribution of AQP5 in a mouse lung epithelial cell line (MLE-12). LPS caused significant increases in AQP5 in the plasma membrane at 0.5-2 h. Immunofluorescence and Western blotting strongly suggested that LPS altered AQP5 subcellular distribution from an intracellular vesicular compartment to the plasma membrane. The specific p38 MAP kinase inhibitor SB 203580 apparently prevented LPS-induced changes in AQP5 distribution. Furthermore, LPS increased the osmotic water permeability of MLE-12 cells. These findings demonstrate that LPS increases cell surface AQP5 expression by changing its subcellular distribution and increases membrane osmotic water permeability through activation of p38 MAP kinase. 相似文献
18.
Ovarian and body cavity eggs from R. temporaria were exposed to radiofrequency (rf) electromagnetic fields in the frequency range 10-27 MHz with specific absorption rates (SAR) up to 800 W/kg. The effect of the exposure was investigated by measurement of the water-related cell physiological parameters, isotopic and osmotic water membrane permeability and density of the egg cells. Only the osmotic water permeability, Pf, of ovarian eggs was significantly altered. A decrease of about 30% was seen for SARs of 50 W/kg and exposure times up to 2 h. Tests ruled out that the effect was due to temperature increase during the exposure. The observed decrease of Pf was most likely due to cloudy swelling of the egg cytoplasm resulting from the rf irradiation. 相似文献
19.
It has been hypothesized that pores in the plasma membrane form under conditions of rapid water efflux, allowing extracellular ice to grow into the cytoplasm under conditions of rapid freezing. When cells with intracellular ice are thawed slowly, the transmembrane ice crystal expands through recrystallization causing the cell to lyse. One of the implications of this hypothesis is that osmotic pores will provide an alternative route for water movement under conditions of osmotically induced flow. We show that the plasma membrane water permeability of a fibroblast cell changes as a function of the osmotic pressure gradient that is used to drive water movement. It is further shown that cell volume is more important than the magnitude of water flux in causing this departure from a uniform water permeability. We suggest that these data provide evidence of a transient route for water movement across cell membranes. 相似文献
20.
Ia Iu Komissarchik Iu V Natochin V I Romanov E S Snigirevskaia E I Shakhmatova 《Tsitologiia》1986,28(5):506-511
Extraction of Ca++ ions from cells of the frog urinary bladder serosa side is followed by an increase in the bladder wall permeability for water and inulin. Ultrastructural changes were observed, such as destruction of cell junctions, swelling of the cell and their organelles, reconstruction of the cytoskeleton elements. The free calcium Ringer solution injected in the bladder lumen does not change the permeability of the wall for water and sodium ions. In this case the cell response to the antidiuretic hormone decreases; the ultrastructure of cells and intercellular junctions is not disturbed; the distribution of intramembrane particles on the P- and E-faces of the apical membrane is normal. The above results indicate that there are qualitative differences in the cell response towards the extraction of Ca++-ions between the serosal and mucosal membranes. This also suggests that on the external surface of the apical membrane Ca++ ions may play a very important role in redistribution of intramembrane particles under the action of the antidiuretic hormone. 相似文献