The Basis of Osmotic Pressure Maintenance During Expansion Growth in Helianthus annuus Hypocotyls

1976 ◽  
Vol 3 (3) ◽  
pp. 311 ◽  
Author(s):  
DL Mcneil
Keyword(s):  
Osmotic Pressure ◽  
Accumulation Rate ◽  
Sucrose Concentration ◽  
Sugar Accumulation ◽  
Bathing Solution ◽  
Bathing Medium ◽  
Intact Tissue ◽  
Hexose Uptake

In etiolated sunflower (H. annuus) hypocotyls, the intracellular osmotic pressure was maintained in spite of the dilution caused by growth. The principal osmotic substances present were hexoses (44 � 6 mol m-3 glucose and 40 � 5 mol m-3 fructose) and organic potassium salts (30 mol m-3). , Potassium fluxes in vivo (intact rooted seedlings) and in vitro (1 cm, peeled, cut sections in an aerated bathing solution) were similar, indicating that the sectioning had not affected cell fluxes. The uptake of 3-O-methyl glucose by cut sections from a bathing medium was lower than the uptake estimated using intact tissue (in vitro influx was 5 % of the net accumulation rate of intact tissue). This suggested that some pathway of hexose uptake other than from the extracellular spaces occurred in vivo. To explain this difference in reducing sugar accumulation rates the following pathway is suggested: (1) Transport of sucrose from the cotyledons via the phloem; (2) Direct unloading of the sucrose into the symplast; (3) Transport of the sucrose into the vacuole down a sucrose concentration gradient maintained by hydrolysis of sucrose to glucose and fructose; (4) Low hexose efflux from the vacuole (5 % of in vivo influx), preventing loss from the vacuole.

In Vitro Germination of Eucalyptus Pollen: Response to Variation in Boric Acid and Sucrose

1989 ◽  
Vol 37 (5) ◽  
pp. 429 ◽  
Author(s):  
BM Potts ◽  
JB Marsden-Smedley
Keyword(s):  
Pollen Tube ◽  
Boric Acid ◽  
Pollen Tube Growth ◽  
Pollen Germination ◽  
Sucrose Concentration ◽  
Response Surfaces ◽  
Tube Growth ◽  
Pollen Competition

The effect of boric acid (0-450 ppm) and sucrose (0-40%) on pollen germination and pollen tube growth in Eucalyptus globulus, E. morrisbyi, E. ovata and E. tirnigera was examined in vitro. Over the con- centrations tested, sucrose had by far the largest effect upon both pollen germination and tube lengths. The optimum sucrose concentration for pollen germination (30%) and pollen tube growth (20%) differed markedly with very little (<lo%) germination occurring in the absence of sucrose. The interaction of sucrose and boric acid was significant. However, in general both pollen germination and pollen tube growth were increased by the addition of up to 100 ppm boric acid, but above this level the response plateauxed. The four species differed significantly in their pattern of response to both boric acid and sucrose and the predicted optima derived from analysis of response surfaces differed between species. The predicted sucrose concentration for optimal germination and growth of E. urnigera pollen was consistently less than the other species and in terms of the optimal level of boric acid for pollen tube growth species can be ranked in the order E. globulus > E. ovata > E. morrisbyi = E. urnigera. Pollen germination and tube growth of all four species on a medium comprising 20% sucrose and 200 ppm boric acid would not differ significantly from the observed maximum response of each species and this could suffice as a generalised medium. However, if only percentage germination is to be assessed 30% sucrose would be preferable. It is argued that subtle interspecific differences in optimal in vitro con- ditions for pollen germination and pollen tube growth are likely to reflect differences in pollen physiology which in vivo may have important implications for the success of hybridisation where pollen competition occurs.

Long-term Adaptations of Sabella Giant Axons to Hyposmotic Stress

1978 ◽  
Vol 75 (1) ◽  
pp. 253-263
Author(s):  
J. E. TREHERNE ◽  
Y. PICHON
Keyword(s):  
Sea Water ◽  
Potassium Concentration ◽  
Resting Potential ◽  
Sodium Permeability ◽  
Bathing Medium ◽  
Appreciable Change ◽  
Axon Membrane ◽  
Giant Axons

Reprint requests should be addressed to Dr Treherne. Sabella is a euryhaline osmoconformer which is killed by direct transfer to 50% sea water, but can adapt to this salinity with progressive dilution of the sea water. The giant axons were adapted to progressive dilution of the bathing medium (both in vivo and in vitro) and were able to function at hyposmotic dilutions (down to 50%) sufficient to induce conduction block in unadapted axons. Hyposmotic adaptation of the giant axon involves a decrease in intracellular potassium concentration which tends to maintain a relatively constant resting potential during adaptation despite the reduction in external potassium concentration. There is no appreciable change in the intracellular sodium concentration, but the relative sodium permeability of the active membrane increases during hyposmotic adaptation. This increase partially compensates for the reduction in sodium gradient across the axon membrane, during dilution of the bathing media, by increasing the overshoot of the action potentials recorded in hyposmotically adapted axons.

The Sensitivity of the Pedal Ganglion of the Slug to Osmotic Pressure Changes

1956 ◽  
Vol 33 (3) ◽  
pp. 493-501
Author(s):  
G. A. KERKUT ◽  
B. J. R. TAYLOR
Keyword(s):  
Osmotic Pressure ◽  
Ionic Concentration ◽  
The Body ◽  
Bathing Solution ◽  
Pedal Ganglion ◽  
Bathing Medium ◽  
Rates Of Change ◽  
Fluid Concentration ◽  
Locke Solution ◽  
Pressure Changes

1. The effects of different dilutions of Locke solution on the electrical activity of the isolated pedal ganglion of the slug can be reproduced by adding different concentrations of glucose of mannitol to a given concentration of Locke. 2. This indicates that certain cells in the pedal ganglion are sensitive to the osmotic pressure of the solution and not its ionic concentration. 3. The preparation is sensitive to slow changes in the concentration of the bathing medium. The cells increased their activity when the bathing solution was slowly changed from 0.7 Locke to 0.6 Locke, the change taking 43 min. This corresponds approximately to a change of 1% of the body fluid concentration over 4 min. Such rates of change are found in the normal intact animal. 4. The sensitivity of the preparation compares well with that of the mammalian osmoreceptors.

scholarly journals Co-Delivery of CPT-11 and Panobinostat with Anti-GD2 Antibody Conjugated Immunoliposomes for Targeted Combination Chemotherapy

Cancers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3211
Author(s):  
Gils Jose ◽  
Yu-Jen Lu ◽  
Jung-Tung Hung ◽  
Alice L. Yu ◽  
Jyh-Ping Chen
Keyword(s):  
Combination Chemotherapy ◽  
Therapeutic Efficacy ◽  
Imaging System ◽  
Accumulation Rate ◽  
Fold Increase ◽  
Drug Uptake ◽  
Mice Model ◽  
Resistant Variant

The consistent expression of disialoganglioside GD2 in neuroblastoma tumor cells and its restricted expression in normal tissues open the possibility to use it for molecularly targeted neuroblastoma therapy. On the other hand, immunoliposomes combining antibody-mediated tumor recognition with liposomal delivery of chemotherapeutics have been proved to enhance therapeutic efficacy in brain tumors. Therefore, we develop immunoliposomes (ImmuLipCP) conjugated with anti-GD2 antibody, for targeted co-delivery of CPT-11 and panobinostat in this study. U87MG human glioma cell line and its drug resistant variant (U87DR), which were confirmed to be associated with low and high expression of cell surface GD2, were employed to compare the targeting efficacy. From in vitro cytotoxicity assay, CPT-11 showed synergism drug interaction with panobinostat to support co-delivery of both drugs with ImmuLipCP for targeted synergistic combination chemotherapy. The molecular targeting mechanism was elucidated from intracellular uptake efficacy by confocal microscopy and flow cytometry analysis, where 6-fold increase in liposome and 1.8-fold increase in drug uptake efficiency was found using targeted liposomes. This enhanced intracellular trafficking for drug delivery endows ImmuLipCP with pronounced cytotoxicity toward U87DR cells in vitro, with 1.6-fold increase of apoptosis rate. Using xenograft nude mice model with subcutaneously implanted U87DR cells, we observe similar biodistribution profile but 5.1 times higher accumulation rate of ImmuLip from in vivo imaging system (IVIS) observation of Cy5.5-labelled liposomes. Taking advantage of this highly efficient GD-2 targeting, ImmuLipCP was demonstrated to be an effective cancer treatment modality to significantly enhance the anti-cancer therapeutic efficacy in U87DR tumors, shown from the significant reduced tumor size in and prolonged survival time of experiment animals as well as diminished expression of cell proliferation and enhanced expression of apoptosis marker proteins in tumor section.

Bioactivity of cholecystokinin analogues: CCK-8 is not more potent than CCK-33

1984 ◽  
Vol 247 (1) ◽  
pp. G105-G111 ◽  
Author(s):  
T. E. Solomon ◽  
T. Yamada ◽  
J. Elashoff ◽  
J. Wood ◽  
C. Beglinger
Keyword(s):  
Guinea Pig ◽  
Pancreatic Secretion ◽  
Gallbladder Contraction ◽  
Bathing Medium ◽  
Structural Analogues ◽  
Biological Actions

We determined the relative molar potencies of structural analogues of porcine cholecystokinin (CCK-39, CCK-33, CCK-8, and caerulein). Peptide concentrations delivered in infusates or present in bathing medium were measured by radioimmunoassay. The presence of albumin prevented loss of CCK-39 and CCK-33 from solution to a greater degree than loss of CCK-8 and caerulein from solution. As much as 10-fold differences in CCK-33 and CCK-39 concentrations were seen in albumin-containing versus nonalbumin-containing infusates. The potency estimates calculated from radioimmunoassay-corrected concentrations with CCK-8 as standard (potency 1.00) were canine pancreatic secretion in vivo: CCK-39 4.1, CCK-33 2.2, and caerulein 2.1; rat pancreatic secretion in vivo: CCK-39 2.1, CCK-33 5.4, and caerulein 5.4; rat pancreatic secretion in vitro: CCK-33 1.7, and caerulein 1.2; guinea pig gallbladder contraction in vivo: CCK-33 1.3, and caerulein 0.9; and guinea pig gallbladder contraction in vitro: CCK-33 1.8, and caerulein 5.8. Our data indicate that CCK-8 is not more potent than longer analogues and suggest that larger forms of CCK may be important mediators of the biological actions of CCK.

Correlation between osmoregulation and cell volume regulation

1987 ◽  
Vol 252 (4) ◽  
pp. R768-R773
Author(s):  
M. A. Lang
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Osmotic Pressure ◽  
Cell Volume ◽  
Free Amino Acids ◽  
Volume Regulation ◽  
Free Amino ◽  
Cell Volume Regulation

The euryhaline crab, Callinectes sapidus, behaves both as an osmoregulator when equilibrated in salines in the range of 800 mosM and below and an osmoconformer when equilibrated in salines above 800 mosM. There exists a close correlation between osmoregulation seen in the whole animal in vivo and cell volume regulation studied in vitro. Hyperregulation of the hemolymph osmotic pressure and cell volume regulation both occurred in salines at approximately 800 mosM and below. During long-term equilibration of the crabs to a wide range of saline environments, the total concentration of hemolymph amino acids plus taurine remained below 3 mM. During the first 6 h after an acute osmotic stress to the whole animal, the hemolymph osmotic pressure and Na activity gradually decreased, whereas the free amino acids remained below 3 mM. As the hemolymph osmotic pressure decreased below approximately 850 mosM, the amino acid level began to increase to 17-25 mM. This change was primarily due to increases in glycine, proline, taurine, and alanine. The likely source of the increase in hemolymph free amino acids in vivo is the free amino acid loss from muscle cells observed during cell volume regulation in vitro.

Water and electrolyte transport by rabbit esophagus

1975 ◽  
Vol 229 (2) ◽  
pp. 438-443 ◽  
Author(s):  
DW Powell ◽  
SM Morris ◽  
DD Boyd
Keyword(s):  
Sodium Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Electrolyte Transport ◽  
Potential Difference ◽  
Sodium Absorption ◽  
Bathing Solution ◽  
Electrical Potential Difference

The nature of the transmural electrical potential difference and the characteristics of water and electrolyte transport by rabbit esophagus were determined with in vivo and in vitro studies. The potential difference of the perfused esophagus in vivo was -28 +/- 3 mV (lumen negative). In vitro the potential difference was -17.9 +/- 0.6 mV, the short-circuit current 12.9 +/- 0.6 muA/cm2, and the resistance 1,466 +/- 43 ohm-cm2. Net mucosal-to-serosal sodium transport from Ringer solution in the short-circuited esophagus in vitro accounted for 77% of the simultaneously measured short-circuit current and net serosal-to-mucosal chloride transport for 14%. Studies with bicarbonate-free, chloride-free, and bicarbonate-chloride-free solutions suggested that the net serosal-to mucosal transport of these two anions accounts for the short-circuit current not due to sodium absorption. The potential difference and short-circuit current were saturating functions of bathing solution sodium concentration and were inhibited by serosal ouabain and by amiloride. Thus active mucosal-to-serosal sodium transport is the major determinant of the potential difference and short-circuit current in this epithelium.

In vitro and in vivo interactions between Erwinia amylovora and related saprophytic bacteria

1975 ◽  
Vol 21 (1) ◽  
pp. 35-41 ◽  
Author(s):  
J. M. Erskine ◽  
L. E. Lopatecki
Keyword(s):  
Erwinia Amylovora ◽  
Virulent Strain ◽  
Sucrose Concentration ◽  
Sugar Content ◽  
Susceptible Host ◽  
The Status ◽  
Highly Virulent ◽  
Host Tissues

Under carefully controlled laboratory conditions, a highly virulent strain of Erwinia amylovora coinhabited susceptible host tissues with a yellow saprophytic bacterium, which was invariably isolated from fire blight infected trees, with or without producing symptoms of the disease depending on the status of a number of environmental factors, both climatic and physiological. In particular, variation of temperature and sucrose concentration determined, independently, the equilibrium of a readily reversible alternation of predominance of the two bacteria.It is suggested that E. amylovora may sometimes exist as an avirulent resident on the surface or within healthy host plants when environmental conditions favor growth of the yellow saprophyte rather than the pathogen. Such conditions, which are more likely to be obtained in midsummer and the fall, include temperature fall or rise below or above the optimum for E. amylovora, decreased humidity or diminution of sap flow, and increased sugar content in the host tissues.

scholarly journals The role of endoplasmic reticulum in in vivo cancer FDG kinetics

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252422
Author(s):  
Sara Sommariva ◽  
Mara Scussolini ◽  
Vanessa Cossu ◽  
Cecilia Marini ◽  
Gianmario Sambuceti ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cancer Metabolism ◽  
Cultured Cells ◽  
Accumulation Rate ◽  
Compartment Model ◽  
Compartment System ◽  
Positron Emission Tomography Scanner ◽  
Three Compartment Model

A recent result obtained by means of an in vitro experiment with cancer cultured cells has configured the endoplasmic reticulum as the preferential site for the accumulation of 2-deoxy-2-[18F]fluoro-D-glucose (FDG). Such a result is coherent with cell biochemistry and is made more significant by the fact that the reticular accumulation rate of FDG is dependent upon extracellular glucose availability. The objective of the present paper is to confirm in vivo the result obtained in vitro concerning the crucial role played by the endoplasmic reticulum in FDG cancer metabolism. This study utilizes data acquired by means of a Positron Emission Tomography scanner for small animals in the case of CT26 models of cancer tissues. The recorded concentration images are interpreted within the framework of a three-compartment model for FDG kinetics, which explicitly assumes that the endoplasmic reticulum is the dephosphorylation site for FDG in cancer cells. The numerical reduction of the compartmental model is performed by means of a regularized Gauss-Newton algorithm for numerical optimization. This analysis shows that the proposed three-compartment model equals the performance of a standard Sokoloff’s two-compartment system in fitting the data. However, it provides estimates of some of the parameters, such as the phosphorylation rate of FDG, more consistent with prior biochemical information. These results are made more solid from a computational viewpoint by proving the identifiability and by performing a sensitivity analysis of the proposed compartment model.

In vitro sensitivity of median preoptic neurons to angiotensin II, osmotic pressure, and temperature

1993 ◽  
Vol 264 (6) ◽  
pp. R1200-R1205 ◽  
Author(s):  
K. A. Travis ◽  
A. K. Johnson
Keyword(s):  
Angiotensin Ii ◽  
Osmotic Pressure ◽  
Fluid Balance ◽  
Plasma Osmolality ◽  
Ang Ii ◽  
In Vivo Experiments ◽  
Single Unit Recordings ◽  
Body Fluid Balance

In vivo experiments suggest an interaction of the mechanisms involved in the regulation of body fluid balance and body temperature. Increases in plasma osmolality initiate drinking and increase the thermal set point for sweating. The median preoptic nucleus (MnPO) has anatomical connections with brain areas important in fluid balance and cardiovascular regulation and, with the preoptic-anterior hypothalamus, a thermoregulatory region. The present experiments employed in vitro single-unit recordings to determine the sensitivity of MnPO neurons to angiotensin II (ANG II), changes in osmotic pressure, and changes in temperature. One-fifth (11 of 55) of the MnPO neurons responded with changes in firing rate during the ANG II treatment, one-fourth (19 of 75) responded to changes in perfusate osmolality, and there was a significant effect of osmolality and ANG II on the thermosensitivity of 25% of the neurons tested.

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