scholarly journals Differentiation of two distinct K conductances in the basolateral membrane of turtle colon.

1986 ◽  
Vol 88 (2) ◽  
pp. 237-251 ◽  
Author(s):  
W J Germann ◽  
M E Lowy ◽  
S A Ernst ◽  
D C Dawson
Keyword(s):  
Physical Properties ◽  
Relative Abundance ◽  
Ion Selectivity ◽  
Basolateral Membrane ◽  
The Other ◽  
Tracer Kinetics ◽  
Present Evidence ◽  
K Channels ◽  
Cell Layers ◽  
Different Populations

The K conductance of the basolateral membrane of turtle colon was measured in amphotericin-treated cell layers under a variety of ionic conditions. Changing the composition of the bathing solutions changed not only the magnitude but also the physical properties of the basolateral K conductance. The results are consistent with the notion that altered ionic environments can lead to changes in the relative abundance of two different populations of K channels in the basolateral membrane, which can be differentiated on the basis of pharmacological specificity, ion selectivity, and tracer kinetics. In the following article (Germann, W. J., S. A. Ernst, and D. C. Dawson, 1986, Journal of General Physiology, 88:253-274), we present evidence consistent with the hypothesis that one of these conductances was due to the same channels that give rise to the normal resting basolateral K conductance of the transporting cells, while the other was associated with experimental maneuvers that led to extreme swelling of the epithelial cells.

scholarly journals Digitonin-permeabilized colonic cell layers. Demonstration of calcium-activated basolateral K+ and Cl- conductances.

1988 ◽  
Vol 92 (3) ◽  
pp. 281-306 ◽  
Author(s):  
D Chang ◽  
D C Dawson
Keyword(s):  
Ion Selectivity ◽  
Basolateral Membrane ◽  
Permeability Barrier ◽  
Buffer System ◽  
Bathing Solution ◽  
Marker Enzyme ◽  
Cell Layers ◽  
Mucosal Side ◽  
Apical Membranes ◽  
Conductive Properties

Sheets of isolated turtle colon were exposed to digitonin on the mucosal side to chemically remove the apical membrane as a permeability barrier. Increases in the mucosal uptake of 86Rb, [3H]mannitol, and 45Ca-EGTA, and the appearance of the cytosolic marker enzyme lactate dehydrogenase in the mucosal bath confirmed the permeabilizing effect of the detergent. Basolateral K+ and Cl- currents were generated by imposing transmural ion gradients, and cytosolic free Ca2+ was manipulated by means of a Ca2+-EGTA buffer system in the mucosal bathing solution. Raising the cytosolic free Ca2+ concentration from the nanomolar to the micromolar range activated basolateral conductances for K+ and Cl-. Differences in ion selectivity, blocker specificity, calcium activation kinetics, and divalent cation activation selectivity indicated that the Ca2+-induced increases in the K+ and Cl- conductances were due to separate populations of channels. The results are consistent with the notion that the apical membranes of turtle colon epithelial cells can be functionally removed under conditions that preserve some of the conductive properties of the basolateral membrane, specifically Ca2+-activated conductive pathways for K+ and Cl-. This permeabilized preparation should offer a means for the identification of macroscopic currents that are due to presumed Ca2+-activated channels, and may also provide a model system for the functional reconstitution of channel regulatory mechanisms.

HAYNES STELLITE ALLOY No. 98M2

Alloy Digest ◽  
1960 ◽  
Vol 9 (7) ◽  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Physical Properties ◽  
Room Temperature ◽  
Base Alloy ◽  
Heat Treating ◽  
The Other ◽  
Stellite Alloy ◽  
Cobalt Base Alloy ◽  
Cobalt Base

Abstract HAYNES STELLITE 98M2 Alloy is a cobalt-base alloy having higher compressive strength and higher hardness than all the other cobalt-base alloys at room temperature and in the red heat range. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive strength as well as fracture toughness. It also includes information on heat treating, machining, and joining. Filing Code: Co-22. Producer or source: Haynes Stellite Company.

scholarly journals IX. The electric conductivity of nitric acid

1898 ◽  
Vol 191 ◽  
pp. 365-398 ◽  
Keyword(s):  
Nitric Acid ◽  
Physical Properties ◽  
Nitrous Acid ◽  
Internal Resistance ◽  
The Other ◽  
Reasonable Degree ◽  
Mineral Acids ◽  
Artificial Illumination ◽  
The Subject ◽  
Deep Green

Of the commoner mineral acids the chemical changes of Nitric Acid, from their evident complexity, have formed the subject of numerous memoirs, while those of sulphuric acid, from their assumed simplicity, have been to some degree neglected; on the other hand, the physical properties of the latter have been studied with considerable elaboration, while those of the former have been passed over, doubtless on account of the corrosive nature of the acid and the difficulty of preparing and preserving it in a reasonable degree of purity. Further, with certain exceptions, the alterations in physical properties induced by the products of reduction, be they nitrogen peroxide or nitrous acid, either singly or conjointly, have attracted but little attention, though it is a common matter of observation that the current intensity of a Grove’s or other cell containing nitric acid remains constant, even though the fuming acid, originally colourless or red, has become of a deep green tint. It is more than probable that of the factors of Ohm’s law, both the E. M. F. and internal resistance are continually varying. At the earliest stages of the enquiry it was found that the passage of a few bubbles of nitric oxide gas into a considerable volume of nitric acid produced an alteration of one percent, in the resistance, and the same result could be effected to a less degree by exposure to sunlight, and to a still less degree by exposure to artificial illumination. Therefore, we determined to investigate the alterations of conductivity produced by changes of concentration and temperature in samples of acid purified with necessary precautions, more especially as former workers upon the subject have either used samples of acid confessedly impure, or have been silent as to any method of purification, or have adopted no special care in dealing with a substance so susceptible of polarisation.

scholarly journals Some Preliminary Notes on the Physical Properties of the Soils of the Ganges Valley, more especially in their relation to Soil Moisture

1906 ◽  
Vol 1 (4) ◽  
pp. 454-469 ◽  
Author(s):  
H. M. Leake
Keyword(s):  
Soil Moisture ◽  
Physical Properties ◽  
Short Duration ◽  
Irrigation Water ◽  
The Other ◽  
Indian Agriculture ◽  
Northern India ◽  
The One ◽  
The Ganges

In a stretch of arable lands like those of the Ganges Valley, although damage may be caused by occasional floods, which are sudden and of short duration, the more general, and by far the most serious loss is due to deficiency of moisture of the soil: thus the relation of the soil to soil moisture becomes of more than ordinary importance. Dr Voelcker, in his Report on Indian Agriculture, remarks: “In India the relation of soils to moisture acquires a greater significance than almost anywhere else.......” This relation is fundamental, for on it depends the methods for the conservation of soil moisture, for the economical application of irrigation water, and for the treatment of barren and salt lands—all problems of direct interest to agriculturists in the plains of Northern India. The methods for dealing with these problems must be largely—if not entirely—empirical until such time as the behaviour of the soil in its relation to moisture is investigated. The problem in all its various branches is enormous, and in a country in which the seasons follow each other with such rapidity, and vary the one from the other in so marked a manner, it frequently happens that a particular point, if not determined within a period of a few days, must await solution until the following year.

scholarly journals Electrophysiological effects of basolateral [Na+] in Necturus gallbladder epithelium.

1992 ◽  
Vol 99 (2) ◽  
pp. 241-262 ◽  
Author(s):  
G A Altenberg ◽  
J S Stoddard ◽  
L Reuss
Keyword(s):  
Apical Membrane ◽  
Basolateral Membrane ◽  
Membrane Resistance ◽  
Membrane Voltage ◽  
Gallbladder Epithelium ◽  
K Channels ◽  
Necturus Gallbladder ◽  
Electrophysiological Effects ◽  
Paracellular Diffusion ◽  
Cl Conductance

In Necturus gallbladder epithelium, lowering serosal [Na+] ([Na+]s) reversibly hyperpolarized the basolateral cell membrane voltage (Vcs) and reduced the fractional resistance of the apical membrane (fRa). Previous results have suggested that there is no sizable basolateral Na+ conductance and that there are apical Ca(2+)-activated K+ channels. Here, we studied the mechanisms of the electrophysiological effects of lowering [Na+]s, in particular the possibility that an elevation in intracellular free [Ca2+] hyperpolarizes Vcs by increasing gK+. When [Na+]s was reduced from 100.5 to 10.5 mM (tetramethylammonium substitution), Vcs hyperpolarized from -68 +/- 2 to a peak value of -82 +/- 2 mV (P less than 0.001), and fRa decreased from 0.84 +/- 0.02 to 0.62 +/- 0.02 (P less than 0.001). Addition of 5 mM tetraethylammonium (TEA+) to the mucosal solution reduced both the hyperpolarization of Vcs and the change in fRa, whereas serosal addition of TEA+ had no effect. Ouabain (10(-4) M, serosal side) produced a small depolarization of Vcs and reduced the hyperpolarization upon lowering [Na+]s, without affecting the decrease in fRa. The effects of mucosal TEA+ and serosal ouabain were additive. Neither amiloride (10(-5) or 10(-3) M) nor tetrodotoxin (10(-6) M) had any effects on Vcs or fRa or on their responses to lowering [Na+]s, suggesting that basolateral Na+ channels do not contribute to the control membrane voltage or to the hyperpolarization upon lowering [Na+]s. The basolateral membrane depolarization upon elevating [K+]s was increased transiently during the hyperpolarization of Vcs upon lowering [Na+]s. Since cable analysis experiments show that basolateral membrane resistance increased, a decrease in basolateral Cl- conductance (gCl-) is the main cause of the increased K+ selectivity. Lowering [Na+]s increases intracellular free [Ca2+], which may be responsible for the increase in the apical membrane TEA(+)-sensitive gK+. We conclude that the decrease in fRa by lowering [Na+]s is mainly caused by an increase in intracellular free [Ca2+], which activates TEA(+)-sensitive maxi K+ channels at the apical membrane and decreases apical membrane resistance. The hyperpolarization of Vcs is due to increase in: (a) apical membrane gK+, (b) the contribution of the Na+ pump to Vcs, (c) basolateral membrane K+ selectivity (decreased gCl-), and (d) intraepithelial current flow brought about by a paracellular diffusion potential.

In vitro measurements of the competitive interactions between two saprobic basidiomycetes on Typha latifolia

2005 ◽  
Vol 83 (11) ◽  
pp. 1523-1527 ◽  
Author(s):  
Michael J. Schulz ◽  
James F. Cahill, ◽  
Randolph S. Currah
Keyword(s):  
Relative Abundance ◽  
Typha Latifolia ◽  
The Other ◽  
Competitive Interactions ◽  
In Vitro Measurements ◽  
Leaf Tissues ◽  
Leaf Segments

Psathyrella typhae (Kalchbr.) Pearson & Dennis forms small basidiomata (mushrooms) and Sclerotium hydrophilum Saccardo in Rothert numerous minute sclerotia at the base of senescent shoots of Typha latifolia L. To assess how the two might compete in nature, isolates of these fungi were paired on autoclaved leaf segments of T. latifolia and incubated at 15 and 25 °C. The relative abundance of each species in the segments was determined by macerating the leaf tissues and then transferring fragments of macerate to microplates containing two types of media: one conclusively demonstrated the presence of P. typhae while the other demonstrated the presence of S. hydrophilum. Relative numbers of microplate wells showing positive reactions for each species on each medium indicated the proportion of the segment occupied following single and paired inoculations. These data demonstrated that competition was asymmetric, with P. typhae the stronger competitor at both temperatures, and uninhibited by the presence of S. hydrophilum. In contrast, S. hydrophilum was competitively excluded by P. typhae.

scholarly journals Chemical control of different Digitaria insularis populations and management of a glyphosate-resistant population

2015 ◽  
Vol 33 (1) ◽  
pp. 93-101 ◽  
Author(s):  
N.M. CORREIA ◽  
L.T. ACRA ◽  
G. BALIEIRO
Keyword(s):  
Chemical Control ◽  
Standard Treatment ◽  
The Other ◽  
Effective Strategy ◽  
Grain Production ◽  
Resistant Population ◽  
Different Populations ◽  
Glyphosate Herbicide ◽  
Combination Of Methods ◽  
Adult Plants

This study aimed to control different populations of Digitaria insularisby glyphosate herbicide, isolated and mixed, besides the combination of methods (chemical and mechanical) to manage resistant adult plants. Three experiments were conducted, one in pots which were maintained under non-controlled conditions and two under field conditions. In the experiment in pots, twelve populations of D. insularis were sprayed with isolated glyphosate (1.44 and 2.16 kg a.e. ha-1) and mixed (1.44 and 2.16 kg a.e. ha-1) with quizalofop-p tefuryl (0.12 kg i.a. ha-1). The treatment of 1.44 kg a.e. ha-1 of glyphosate plus 0.12 kg a.i. ha-1 of quizalofop was sufficient for adequate control (>95%) of all populations. Population 11 (area of grain production in Itumbiara, GO) was considered sensitive to glyphosate. Others populations were moderately sensitive or tolerant to the herbicide. In the field, the plants of D. insularis of one of the experiments were mowed and, in the other, there were not. Eight treatments with herbicides [isolated glyphosate (1.44 and 2.16 kg a.e. ha-1) and mixed (1.44 and 2.16 kg a.e. ha-1) with quizalofop-p-tefuryl at 0.12 kg a.i. ha-1), clethodim at 0.108 kg a.i. ha-1) or nicosulfuron at 0.06 kg a.i. ha-1)] were assessed, in combination with or without sequential application of the standard treatment, sprayed 15 days after the first application. The combination of the mechanic control with the application of glyphosate (2.16 and 1.44 kg a.e. ha-1) plus quizalofop-p-tefuryl (0.12 kg a.i. ha-1) or clethodim (0.108 kg a.i. ha-1), associated to the sequential application, was the most effective strategy for the management of adult plants of resistant D. insularis.

scholarly journals JKRW Link Prediction – A New Ensemble Technique Based on Merging Other Known Techniques in The Social Network Analysis

2021 ◽  
Vol 15 (12) ◽  
pp. 125
Author(s):  
Aya Taleb ◽  
Rizik M. H. Al-Sayyed ◽  
Hamed S. Al-Bdour
Keyword(s):  
Link Prediction ◽  
Preferential Attachment ◽  
Large Data ◽  
The Other ◽  
Jaccard Coefficient ◽  
Ensemble Technique ◽  
Signed Rank ◽  
Proposed Model ◽  
Different Populations ◽  
A New Technique

In this research, a new technique to improve the accuracy of the link prediction for most of the networks is proposed; it is based on the prediction ensemble approach using the voting merging technique. The new proposed ensemble called Jaccard, Katz, and Random models Wrapper (JKRW), it scales up the prediction accuracy and provides better predictions for different sizes of populations including small, medium, and large data. The proposed model has been tested and evaluated based on the area under curve (AUC) and accuracy (ACC) measures. These measures applied to the other models used in this study that has been built based on the Jaccard Coefficient, Katz, Adamic/Adar, and Preferential attachment. Results from applying the evaluation matrices verify the improvement of JKRW effectiveness and stability in comparison to the other tested models.  The results from applying the Wilcoxon signed-rank method (one of the non-parametric paired tests) indicate that JKRW has significant differences compared to the other models in the different populations at <strong>0.95</strong> confident interval.

scholarly journals Interaction of Arsenophonus with Wolbachia in Nilaparvata lugens

2019 ◽  
Author(s):  
Huifang Guo ◽  
Na Wang ◽  
Hongtao Niu ◽  
Dongxiao Zhao ◽  
Zhichun Zhang
Keyword(s):  
Nilaparvata Lugens ◽  
The Other ◽  
Single Infection ◽  
Double Infection ◽  
Infection Incidence ◽  
Significant Difference ◽  
Geographic Populations ◽  
Different Populations ◽  
Symbiont Species ◽  
Antagonistic Interactions

Abstract Background Co-infection of endosymbionts in the same host is ubiquitous, and the interactions of the most common symbiont Wolbachia with other symbionts, including Spiroplasma et al., in invertebrate organisms have received increasing attention. However, the interactions between Wolbachia and Arsenophonus, another widely distributed symbiont in nature, are poorly understood. We tested the co-infection of Wolbachia and Arsenophonus in different populations of Nilaparvata lugens and investigated whether co-infection affected the population size of the symbionts in their host. Results A significant difference was observed in the co-infection incidence of Wolbachia and Arsenophonus among 5 populations of N. lugens from China, with nearly half of the individuals in the Zhenjiang population harbouring the two symbionts simultaneously, and the rate of occurrence was significantly higher than that of the other 4 populations. The Arsenophonus density in the superinfection line was significantly higher only in the Maanshan population compared with that of the single-infection line. Differences in the density of Wolbachia and Arsenophonus were found in all the tested double-infection lines, and the dominant symbiont species varied with the population only in the Nanjing population, with Arsenophonus the overall dominant symbiont. Conclusions Wolbachia and Arsenophonus could coexist in N. lugens, and the co-infection incidence varied with the geographic populations. Antagonistic interactions were not observed between Arsenophonus and Wolbachia, and the latter was the dominant symbiont in most populations.

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