Effect of Low O2 Concentration and Azide on Hydraulic Conductivity and Osmotic Volume of the Cortical Cells of Wheat Roots

1991 ◽  
Vol 18 (6) ◽  
pp. 603 ◽  
Author(s):  
WH Zhang ◽  
SD Tyerman
Keyword(s):  
Hydraulic Conductivity ◽  
Pressure Probe ◽  
Cortical Cells ◽  
Wheat Roots ◽  
Volume Relaxation ◽  
Pressure Relaxation ◽  
Mean Values ◽  
O2 Concentration ◽  
Relaxation Experiments

The short-term effects of O2 deficiency and sodium azide (NaN3) on the hydraulic conductivity of cortical cells in wheat roots was studied using the pressure probe. Hydraulic conductivities were obtained by measuring either turgor relaxation, or volume relaxation under pressure clamp. Both low O2 concentration and NaN3 increased the half times of pressure and volume relaxations. The increases in T½ were found to be due to a decrease in the hydraulic conductivity (Lp) of the cells. The mean values of Lp from pressure relaxation experiments were 7.75 × 10-1m s-1 Mpa-1 in the fully aerated solution and 1.15 and 2.17 x 10-1m s-1 Mpa-1 in low O2 concentration and 1 mol m-3 NaN3 solutions respectively. The pressure clamp experiments yielded similar results to pressure relaxation experiments for both low O2 concentration and 1 mol m-3 NaN3 treatments. In addition to determination of Lp, pressure and volume relaxation experiments were also used to evaluate osmotic volume of the cells. In aerated solutions the osmotic volume of the cells was about twice that of their geometric volume, but in low O2 concentration and NaN3 solutions the osmotic cell volume was reduced and approximately equal to the geometric volume. The decrease in osmotic volume and part of the reduction in Lp may be explained by the occlusion of plasmodesmata induced by low O2 concentration and NaN3.

scholarly journals The contrasting influence of short-term hypoxia on the hydraulic properties of cells and roots of wheat and lupin

2010 ◽  
Vol 37 (3) ◽  
pp. 183 ◽  
Author(s):  
Helen Bramley ◽  
Neil C. Turner ◽  
David W. Turner ◽  
Stephen D. Tyerman
Keyword(s):  
Hydraulic Conductivity ◽  
Water Flow ◽  
Hydraulic Properties ◽  
Turgor Pressure ◽  
Lupinus Luteus ◽  
Yellow Lupin ◽  
Cortical Cells ◽  
Crop Species ◽  
Wheat Roots ◽  
Root Cells

Little is known about water flow across intact root cells and roots in response to hypoxia. Responses may be rapid if regulated by aquaporin activity, but only if water crosses membranes. We measured the transport properties of roots and cortical cells of three important crop species in response to hypoxia (0.05 mol O2 m–3): wheat (Triticum aestivum L.), narrow-leafed lupin (Lupinus angustifolius L.) and yellow lupin (Lupinus luteus L.). Hypoxia influenced solute transport within minutes of exposure as indicated by increases in root pressure (Pr) and decreases in turgor pressure (Pc), but these effects were only significant in lupins. Re-aeration returned Pr to original levels in yellow lupin, but in narrow-leafed lupin, Pr declined to zero or lower values without recovery even when re-aerated. Hypoxia inhibited hydraulic conductivity of root cortical cells (Lpc) in all three species, but only inhibited hydraulic conductivity of roots (Lpr) in wheat, indicating different pathways for radial water flow across lupin and wheat roots. The inhibition of Lpr of wheat depended on the length of the root, and inhibition of Lpc in the endodermis could account for the changes in Lpr. During re-aeration, aquaporin activity increased in wheat roots causing an overshoot in Lpr. The results of this study demonstrate that the roots of these species not only vary in hydraulic properties but also vary in their sensitivity to the same external O2 concentration.

scholarly journals Comparison of pedotransfer functions for the determination of saturated hydraulic conductivity coefficient

2017 ◽  
Vol 28 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Marek Ryczek ◽  
Edyta Kruk ◽  
Magdalena Malec ◽  
Sławomir Klatka
Keyword(s):  
Hydraulic Conductivity ◽  
Direct Methods ◽  
Laboratory Method ◽  
Saturated Hydraulic Conductivity ◽  
Pedotransfer Functions ◽  
United States Bureau ◽  
Empirical Methods ◽  
Mean Values ◽  
Bureau Of Reclamation

Abstract On one hand, direct methods of measurement of saturated hydraulic conductivity coefficient are time consuming, and on the other hand, laboratory methods are cost consuming. That is why the popularity of empirical methods has increased. Their main advantages are speed of calculations and low costs. Comparison of various empirical methods (pedotransfer functions) for the determination of saturated hydraulic conductivity coefficient was the purpose of this work. The methods used were Shepard’s, Hazen’s, USBR (United States Bureau of Reclamation), Saxton et al.’s, Kozeny–Carman’s, Krüger’s, Terzaghi’s, Chapuis’s, Sheelheim’s, Chapuis’, and NAVFAC (Naval Facilities Engineering Command) methods. Calculations were carried out for the soil samples of differential texture. The obtained results shows the methods used for the determination of permeability coefficient differ considerably. Mean values obtained by analysed methods fluctuated between 0.0006 and 12.0 m·day−1. The results of calculations by the chosen methods were compared with the results of the laboratory method. The best compatibility with laboratory method was obtained by using the Terzaghi method.

Research Note: Calibration of micropipettes for pressure-probe studies

1998 ◽  
Vol 25 (8) ◽  
pp. 947
Author(s):  
Ricardo Murphy ◽  
Joseph K.E. Ortega
Keyword(s):  
Water Relation ◽  
Mean Value ◽  
Independent Method ◽  
Pressure Probe ◽  
Cell Water ◽  
Mean Values ◽  
Capillary Tubing ◽  
Oil Water ◽  
Water Meniscus

In order to determine cell water-relation parameters with the pressure probe, the ratio of inner to outer pipette diameters (α = Di/Do) must be estimated. Four different methods for estimating a were compared. I: measurement of the volume of oil expelled from a pipette and the corresponding movement of an oil/water meniscus within the pipette; II: measurement of Di and Do on fractured pipettes; III: measurement of Di and Do on intact pipettes; IV: measurement of Di and Do on capillary tubing. Methods I and II gave mean values for α (± SE) that were in excellent agreement [0.587 ± 0.004 (n = 12), and 0.593 ± 0.003 (n = 14), respectively]. Method III gave variable results for Do < 80µm; for Do > 80 µm a mean value α = 0.624 ±0.007 (n = 4) was obtained. Method IV gave a mean value α = 0.544 ± 0.001 (n = 5). It is suggested that any method for calibrating micropipettes should be checked against an independent method (e.g. Method I) that allows the determination of α for Do < 100 µm. In the present study, Method II gave the best combination of accuracy and convenience.

scholarly journals Experimental investigation to characterize simple versus multi scaling analysis of hydraulic conductivity at a mesoscale

2021 ◽  
Author(s):  
Guglielmo Federico Antonio Brunetti ◽  
Samuele De Bartolo ◽  
Carmine Fallico ◽  
Ferdinando Frega ◽  
Maria Fernanda Rivera Velásquez ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Spatial Variability ◽  
Hydraulic Properties ◽  
Scaling Laws ◽  
Scaling Analysis ◽  
Field Scale ◽  
Porous Formation ◽  
Proper Design ◽  
First Time

AbstractThe spatial variability of the aquifers' hydraulic properties can be satisfactorily described by means of scaling laws. The latter enable one to relate the small (typically laboratory) scale to the larger (typically formation/regional) ones, therefore leading de facto to an upscaling procedure. In the present study, we are concerned with the spatial variability of the hydraulic conductivity K into a strongly heterogeneous porous formation. A strategy, allowing one to identify correctly the single/multiple scaling of K, is applied for the first time to a large caisson, where the medium was packed. In particular, we show how to identify the various scaling ranges with special emphasis on the determination of the related cut-off limits. Finally, we illustrate how the heterogeneity enhances with the increasing scale of observation, by identifying the proper law accounting for the transition from the laboratory to the field scale. Results of the present study are of paramount utility for the proper design of pumping tests in formations where the degree of spatial variability of the hydraulic conductivity does not allow regarding them as “weakly heterogeneous”, as well as for the study of dispersion mechanisms.

Colorimetric Determination of Hydroxyproline as Measure of Collagen Content in Meat and Meat Products: NMKL Collaborative Study

1990 ◽  
Vol 73 (1) ◽  
pp. 54-57 ◽  
Author(s):  
Kurt Kolar
Keyword(s):  
Collaborative Study ◽  
Colorimetric Method ◽  
Meat Products ◽  
Acid Oxidation ◽  
Colorimetric Determination ◽  
Mean Values ◽  
Collaborative Studies ◽  
Freeze Dried ◽  
Analytical Result

Abstract A colorimetric method for the determination of hydroxyproline as a measure of collagen in meat and meat products has been collaboratively studied in 18 laboratories. The method includes hydrolysis with sulfuric acid, oxidation with chloramine- T, and formation of a reddish purple complex with 4- dimethylaminobenzaldehyde. Five frozen and 3 freeze-dried samples were tested, ranging in content from 0.11 to 0.88% and from 0.39 to 4.0% hydroxyproline, respectively. The mean values of 2 identical samples were 0.245 and 0.251 %. The average recovery from a spiked sample was 96.1 %. The hydroxyproline content of a known sample (a mixture of 2 samples in the ratio 5:2) was calculated to 1.42%, which agrees well with the analytical result, 1.40%. In comparison with other collaborative studies, based on the ISO analytical method, the repeatability and reproducibility of this method agree well with the other results. This method was accepted as an official NMKL method by all national Committees, and has been adopted official first action by AOAC as an NMKLAOAC method.

scholarly journals Laboratory and In Situ Determination of Hydraulic Conductivity and Their Validity in Transient Seepage Analysis

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1131
Author(s):  
Soonkie Nam ◽  
Marte Gutierrez ◽  
Panayiotis Diplas ◽  
John Petrie
Keyword(s):  
Hydraulic Conductivity ◽  
Field Measurements ◽  
Natural Soil ◽  
In Situ Tests ◽  
Seepage Analysis ◽  
Soil Deposits ◽  
Seepage Modeling ◽  
Sample Disturbance

This paper critically compares the use of laboratory tests against in situ tests combined with numerical seepage modeling to determine the hydraulic conductivity of natural soil deposits. Laboratory determination of hydraulic conductivity used the constant head permeability and oedometer tests on undisturbed Shelby tube and block soil samples. The auger hole method and Guelph permeameter tests were performed in the field. Groundwater table elevations in natural soil deposits with different hydraulic conductivity values were predicted using finite element seepage modeling and compared with field measurements to assess the various test results. Hydraulic conductivity values obtained by the auger hole method provide predictions that best match the groundwater table’s observed location at the field site. This observation indicates that hydraulic conductivity determined by the in situ test represents the actual conditions in the field better than that determined in a laboratory setting. The differences between the laboratory and in situ hydraulic conductivity values can be attributed to factors such as sample disturbance, soil anisotropy, fissures and cracks, and soil structure in addition to the conceptual and procedural differences in testing methods and effects of sample size.

SENSITIVE AND SPECIFIC ENZYME-LINKED IMMUNOSORBENT ASSAY FOR UROKINASE-TYPE PLASMINOGEN ACTIVATOR IN HUMAN PLASMA

1987 ◽  
Author(s):  
J Grøndahl-HANSEN ◽  
N Agerlin ◽  
L S Nielsen ◽  
K Danø
Keyword(s):  
Plasminogen Activator ◽  
Immunosorbent Assay ◽  
Enzyme Linked Immunosorbent Assay ◽  
Mean Values ◽  
Amino Terminal ◽  
Type Plasminogen Activator ◽  
Healthy Donors ◽  
Urokinase Type Plasminogen Activator ◽  
The Mean

An enzyme-linked immunosorbent assay (ELISA) was developed for the measurement of human urokinase-type plasminogen activator (u-PA) in plasma and serum. Microtiter plates were coated with a monoclonal antibody and incubated with standard or sample. Bound u-PA was quantitated with polyclonal antibodies conjugated with biotin, followed by avidin-peroxidase. The assay was 10-fold as sensitive as other previously reported ELISAs, the detection limit being approximately 1 pg of u-PA in a volume of 100 μl with a linear dose-response up to 15 pg of u-PA. The assay detected active u-PA and its inactive proenzyme form equally well and the recovery of both forms was higher than 90% in plasma. A variety of structurally related proteins, including t-PA, were tested, but no reaction with proteins other than u-PA and its amino-terminal degradation product were observed. The intra-assay and inter-assay coefficients of variation for determination of u-PA in plasma were 7.6% and 8.4%, respectively. The assay was equally applicable to serum. The values obtained with plasma and serum were similar, and the results were not affected by small variations in the preparation of the samples. The ELISA was used to measure the concentration of u-PA in plasma from 34 healthy donors. The mean values for u-PA in plasma from healthy donors was 1.1 ng/ml ± 0.3 ng/ml (SD) (range 0.6 - 1.5 ng/ml). No significant differences were found between men and women and no correlation between u-PA concentration and age could be demonstrated.The mean u-PA concentration in plasma from healthy donors obtained in this study is substantially lower than that reported by others. This might be due to different methods of determination of the protein content of the standard preparations or to differences in the specificity of the assays.

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