Search results for "Cell volume"
showing 10 items of 16 documents
An ecological multi-Level theory of competition for resources used to analyse density-dependence effects in fruit production
2014
International audience; Lescourret and Génard (2003) developed a multi-level theory of competition for resources applied to fruit production, considering that any collection of unit parts (cells or seeds in a fruit, fruits in an infructescence or in a tree...) can form a population and the population is subject to competition, whatever the level of organization. The principles of the theory are that the mass of each unit decreases when the number of units in the population increases and that the total mass of the population increases as the number of units increases until it reaches a maximum, after which it decreases. A three-parameter model based on that theory was used to analyse the lev…
Exercise Effects on Erythrocyte Deformability in Exercise-induced Arterial Hypoxemia
2014
Exercise-induced arterial hypoxemia (EIAH) is often found in endurance-trained subjects at high exercise intensity. The role of erythrocyte deformability (ED) in EIAH has been scarcely explored. We aimed to explore the role of erythrocyte properties and lactate accumulation in the response of ED in EIAH. ED was determined in 10 sedentary and in 16 trained subjects, both before and after a maximal incremental test, and after recovery, along with mean corpuscular volume (MCV) and red blood cell lactate concentrations. EIAH was found in 6 trained subjects (∆SaO2=-8.25±4.03%). Sedentary and non-EIAH trained subjects showed reduced ED after exercise, while no effect on ED was found in EIAH train…
Oxygen Consumption Rate of Tumour Cells as a Function of their Proliferative Status
1987
The oxygen consumption rate \(\left( \dot{Q}{{O}_{2}} \right)\) of EMT6/Ro-cells cultured as monolayers was investigated as a function of their proliferative status. The transition of these cells from the exponential to the plateau growth phase was associated with a continuous decrease in \(\dot{Q}{{O}_{2}}\) per single cell. This decrease can partially be attributed to a corresponding decline in cellular volume. In addition, the \(\dot{Q}{{O}_{2}}\) per cell volume was also reduced during the passage of the cells through the growth phase described. The results lead to the conclusion that a reduction in cellular volume and factors which are still unknown may contribute to the metabolic chan…
Preparation and Investigation of BaSO4KMnO4 Crystals
1969
BaSO4 crystals containing KMnO4 prepared by precipitation were investigated morphologically, chemically and by X-ray diffraction. The colour of the preparations is homogeneous and stable. The colour intensity and also the amount of dissolved KMnO4 (maximum approx. 30 Mol%) increases with concentration of KMnO4 in the reaction solution to a limiting value dependent on the temperature. The lattice constants or the unit cell volume of the BaSO4–KMnO4 crystals increase with the proportion of KMnO4. The experimental values agree well with the Vegard rule for preparations up to 18 Mol% KMnO4, but with higher proportions significant departures were observed. They may easily be explained by adsorpt…
A proton-translocating H+-ATPase is involved in C6 glial pH regulation.
1998
AbstractGlial cells extrude acid equivalents to maintain pHi. Although four mechanisms have been described so far, pHi-control under physiological conditions is still not sufficiently explained. We therefore investigated whether a H+-translocating ATPase is involved in glial pHi homeostasis using an established glial cell line (C6 glioma). In the absence of bicarbonate, the inhibition of H+-ATPases by NEM led to a pHi decrease. The application of a more specific inhibitor (NBD-Cl) showed that the H+-ATPase involved is of the vacuolar type. Inhibition went along with delayed cell swelling. Together with the fact that glial acidification was far more pronounced in Na+-free media, this may ser…
The synthesis of SNAT2 transporters is required for the hypertonic stimulation of system A transport activity
2004
AbstractIn cultured human fibroblasts incubated under hypertonic conditions, the stimulation of system A for neutral amino acid transport, associated to the increased expression of the mRNA for SNAT2 transporter, leads to an expanded intracellular amino acid pool and to the recovery of cell volume. A protein of nearly 60 kDa, recognized by an antiserum against SNAT2, is increased both in the pool of biotinylated membrane proteins and in the total cell lysate of hypertonically stressed cells. The increased level of SNAT2 transporters in hypertonically stressed cells is confirmed by immunocytochemistry. DRB, an inhibitor of transcription, substantially inhibits the increase of SNAT2 proteins …
Blood circulation of long bones in trained growing rats and mice
1975
The effect of physical training on the blood circulation of long bones was studied in growing rats and mice of NMRI-strain. The animals to be trained and their controls were about 2 weeks old at the beginning of the training. The training took place on a 5 degree inclined treadmill 5 days a week for 3 weeks in experiment I and 7 weeks in experiments II and III. The duration of the daily exercise was progressively increased over 3 weeks. The final exercise bouts were 80 min for moderate and 180 min for intensive training programs. The circulating red cell volume (ml/100 g bone) of the humeral, femoral and tibial bones of the trained animals was lower compared to the controls in all three exp…
Insights Into the Inside - A Quantitative Histological Study of the Explosively Moving Style in Marantaceae.
2018
This study aims to identify the histological basis for the extraordinary, fast movement of the style in Marantaceae. Although this explosive pollination mechanism was subject of many studies, quantitative measurements to document volumetric changes have never been conducted. Based on physical parameters and limitations (poroelastic time), the movement itself is by far too fast to be explained by turgor changes solely. Therefore, we address the hypothesis that the style contains elastic structures to store energy allowing the fast movement. We provide an experimental approach in Goeppertia bachemiana to identify histological differences of styles in various states, i.e., steady, unreleased, …
Origin of pressure-induced insulator-to-metal transition in the van der Waals compound FePS3 from first-principles calculations
2020
The authors acknowledge the assistance of the University Computer Center of Saint‐Petersburg State University in the accomplishment of high‐performance computations. A.K. is grateful to the Latvian Council of Science project no. lzp‐2018/2‐0353 for financial support.
Relaxor ferroelectric ceramics of LiTaO3-type
1992
Abstract A ferroelectric relaxation has been identified in Li1-xCax (Ta1-xZrx)O3(x = 0.15 and 0.20) ceramics with LiTaO3-type structure. The relaxation frequency fr is minimum and the dispersion step (ϵ′S - ϵ′∞) is maximum at TC. When x increases, a higher conductivity associated with a lower activation energy and a decrease of the magnitude of fr at Tc are observed, while the unit cell volume becomes larger, TC lower and the transition more diffuse.