scholarly journals KcsA Ion Affinity at an External Site Probed by Barium Block

2011 ◽  
Vol 100 (3) ◽  
pp. 565a ◽  
Author(s):  
Kene N. Piasta ◽  
Christopher Miller
Keyword(s):  
External Site ◽  
Barium Block

World-Ecological Satire: Peat, Brian O'Nolan, and the Irish Free State's Energy Regime

2019 ◽  
Vol 49 (1) ◽  
pp. 90-104
Author(s):  
Robert Kiely
Keyword(s):  
Cultural Production ◽  
Ecological Perspective ◽  
Energy Regime ◽  
Energy History ◽  
History Of ◽  
External Site ◽  
Ecological Relations ◽  
Nature And Society ◽  
Human Actors ◽  
The Relationship

A world-ecological perspective of cultural production refuses a dualist conception of nature and society – which imagines nature as an external site of static outputs  – and instead foregrounds the fact that human and extra-human natures are completely intertwined. This essay seeks to reinterpret the satirical writing of a canonical figure within the Irish literary tradition, Brian O'Nolan, in light of the energy history of Ireland, understood as co-produced by both human actors and biophysical nature. How does the energy imaginary of O'Nolan's work refract and mediate the Irish environment and the socio-ecological relations shaping the fuel supply-chains that power the Irish energy regime dominant under the Irish Free State? I discuss the relationship between peat as fuel and Brian O'Nolan's pseudonymous newspaper columns, and indicate how questions about energy regimes and ecology can lead us to read his Irish language novel An Béal Bocht [The Poor Mouth] (1941) in a new light. The moments I select and analyze from O'Nolan's output feature a kind of satire that exposes the folly of separating society from nature, by presenting an exaggerated form of the myth of nature as an infinite resource.

scholarly journals A Novel Type of Internal Barium Block of a Maxi-K+ Channel from Human Vas Deferens Epithelial Cells

1998 ◽  
Vol 74 (1) ◽  
pp. 199-209 ◽  
Author(s):  
Y. Sohma ◽  
A. Harris ◽  
B.E. Argent ◽  
M.A. Gray
Keyword(s):  
Epithelial Cells ◽  
Vas Deferens ◽  
K Channel ◽  
Barium Block

scholarly journals State‐dependent barium block of wild‐type and inactivation‐deficient HERG channels in Xenopus oocytes

2000 ◽  
Vol 526 (2) ◽  
pp. 265-278 ◽  
Author(s):  
Manjula Weerapura ◽  
Stanley Nattel ◽  
Marc Courtemanche ◽  
David Doern ◽  
Nathalie Ethier ◽  
...  
Keyword(s):  
Xenopus Oocytes ◽  
Wild Type ◽  
State Dependent ◽  
Barium Block ◽  
Herg Channels

scholarly journals Distribution of stem-end rot on the canopy in ‘Hass’ avocado trees in two coastal areas in Peru

2021 ◽  
Vol 5 (2) ◽  
pp. 60-70
Author(s):  
Alejandro Kepler Llanos Melo ◽  
Walter Eduardo Apaza-Tapia
Keyword(s):  
Disease Incidence ◽  
Management Strategies ◽  
Elongation Factor ◽  
Fungal Species ◽  
Coastal Areas ◽  
Tree Canopy ◽  
Fruit Rot ◽  
Internal Site ◽  
External Site ◽  
Hass Avocado

Stem-end rot (SER) of avocado is caused by several fungal species, and it is presented worldwide. This plant disease currently affects several avocado producer regions in Peru, causing fruit rot, impacting the industry negatively. Research about SER distribution in the canopy of avocado trees is limited. Thus, the present study aimed to compare which areas in the canopy are prone to have more SER in ‘Hass’ avocado harvested fruit in two different coastal areas in Peru. The experiment was conducted in the northern (Barranca) and southern (Cañete) of Lima. ‘Hass’Avocado fruits from both producer areas were collected to identify the causal agent; Lasiodiplodia theobromae was isolated from infected fruits. Identification was conducted based on morphological features and a partial DNA sequence of the translation elongation factor 1-α gene (tef1-α). The results showed that fruits inside the tree canopy were prone to have a higher disease incidence than the fruits located in the external site (P<0.001). Besides, internal-site fruits displayed a higher percentage of infected fruit for each grade disease (P<0.001) than external-site fruits, except for grade 0 (fruits without symptoms) and grade 1. Finally, the results suggested that the altitude where the fruit is positioned on the canopy could influence the incidence of SER, where fruits located in the high part revealed less incidence than the low section. The results are valuable for enhancing management strategies and avoiding postharvest loss of avocado fruits in our region.

Role of cyclic GMP in cholinergic activation of Na-K pump in duck salt gland

1981 ◽  
Vol 240 (5) ◽  
pp. C207-C214 ◽  
Author(s):  
D. J. Stewart ◽  
A. K. Sen
Keyword(s):  
Sodium Pump ◽  
Intact Cell ◽  
Salt Gland ◽  
Ringer Solution ◽  
Direct Role ◽  
External Site ◽  
Alternate Substrate ◽  
Hydrolysis Of ◽  
Pnpp Hydrolysis

Na-K-ATPase will hydrolyze an alternate substrate, p-nitrophenylphosphate (pNPP). The hydrolysis is ouabain sensitive and occurs at an external site on the cell membrane, thereby allowing measurement of Na-K-ATPase activity in the intact cell. pNPP hydrolysis was monitored in salt gland slices incubated in a bicarbonate-buffered Ringer solution. Methacholine-stimulated pNPP hydrolysis was inhibited by either atropine or ouabain. The hydrolysis was also dependent on the presence of calcium and sodium in the Ringer solution. cGMP stimulated ouabain-sensitive pNPP hydrolysis at concentrations from 10(-8) M to 10(-4) M with an optimum at 10(-5) M. cAMP did not produce a significant activation of pNPP hydrolysis. The effect of cGMP ws not dependent on either sodium or calcium in the Ringer solution and was not inhibited by atropine. Hydrolysis of pNPP promoted by either methacholine or cGMP occurred under conditions where no net influx of Na+ into the cells could occur. Sodium-pump activation during cholinergic stimulation, therefore, does not depend on an elevation of cell sodium but must occur by another mechanism. cGMP appears to play a direct role in that mechanism.

Ammonium transport by the colonic H+-K+-ATPase expressed in Xenopusoocytes

1999 ◽  
Vol 277 (2) ◽  
pp. C280-C287 ◽  
Author(s):  
Marc Cougnon ◽  
Patrice Bouyer ◽  
Frédéric Jaisser ◽  
Aleksander Edelman ◽  
Gabrielle Planelles
Keyword(s):  
Kinetic Analysis ◽  
Initial Rate ◽  
Functional Expression ◽  
Competitive Inhibitor ◽  
Ammonium Transport ◽  
Xenopus Laevis Oocytes ◽  
Intracellular Acidification ◽  
Extracellular Medium ◽  
Α Subunit ◽  
External Site

Functional expression of the rat colonic H+-K+-ATPase was obtained by coexpressing its catalytic α-subunit and the β1-subunit of the Na+-K+-ATPase in Xenopus laevis oocytes. We observed that, in oocytes expressing the rat colonic H+-K+-ATPase but not in control oocytes (expressing β1 alone), NH4Cl induced a decrease in86Rb uptake and the initial rate of intracellular acidification induced by extracellular NH4Cl was enhanced, consistent with [Formula: see text] influx via the colonic H+-K+-ATPase. In the absence of extracellular K+, only oocytes expressing the colonic H+-K+-ATPase were able to acidify an extracellular medium supplemented with NH4Cl. In the absence of extracellular K+ and in the presence of extracellular [Formula: see text], intracellular Na+ activity in oocytes expressing the colonic H+-K+-ATPase was lower than that in control oocytes. A kinetic analysis of86Rb uptake suggests that[Formula: see text] acts as a competitive inhibitor of the pump. Taken together, these results are consistent with[Formula: see text] competition for K+ on the external site of the colonic H+-K+-ATPase and with [Formula: see text] transport mediated by this pump.

scholarly journals Barium Block of Kv4.2 is Enhanced by Channel Inactivation

2011 ◽  
Vol 100 (3) ◽  
pp. 282a-283a
Author(s):  
Steven J. Kehl ◽  
Yen May Cheng
Keyword(s):  
Channel Inactivation ◽  
Barium Block

Hydroisomerization of Biomass Derived n-Hexadecane Towards Diesel Pool: Effect of Selective Removal External Surface Sites from Pt/ZSM-22

2016 ◽  
Vol 14 (1) ◽  
pp. 155-165 ◽  
Author(s):  
Abhijeet H. Thaker ◽  
Mathew John ◽  
Kishore Kumar ◽  
Mahesh W. Kasture ◽  
Snehalkumar Parmar ◽  
...  
Keyword(s):  
Oxalic Acid ◽  
Active Sites ◽  
External Surface ◽  
Space Velocity ◽  
Product Distribution ◽  
Catalytic Performance ◽  
Selective Removal ◽  
Cold Flow ◽  
External Site ◽  
Kinetics Of

AbstractInfluence of dealumination of zeolite ZSM-22 (Si/Al ratio of 45) by treating it with oxalic acid on its catalytic performance in n-hexadecane hydroisomerization reaction was studied. This reaction is an attempt in the direction of green and sustainable source of diesel via improving the cold-flow properties of deoxygenated vegetable oils. Pt (0.5 wt%) on ZSM-22 treated with 1 M oxalic acid afforded highest yields of the mono-branched paraffins. This improved is attributed to selective removal of active sites on external surface of zeolite crystals (responsible for undesired cracking reactions) using the bulkier dealuminating agent, oxalic acid. Thus, pore-mouth key-lock mechanism was brought to play the role to cause high selectivity to mono-branched isomers. Preferential external site deactivation was inferred from mesitylene cracking results. Effects of operating parameters such as temperature, and space velocity on product distribution also were studied. Also, kinetics of the reactions involved too has been in brief reported.

scholarly journals Tuning the Voltage Dependence of Tetraethylammonium Block with Permeant Ions in an Inward-Rectifier K+ Channel

1999 ◽  
Vol 114 (3) ◽  
pp. 415-426 ◽  
Author(s):  
Maria Spassova ◽  
Zhe Lu
Keyword(s):  
Alkali Metal ◽  
Metal Ions ◽  
Ion Selectivity ◽  
Inward Rectifier ◽  
K Channel ◽  
Alkali Metal Ions ◽  
Internal Site ◽  
External Site ◽  
Ion Binding Sites

To understand the role of permeating ions in determining blocking ion–induced rectification, we examined block of the ROMK1 inward-rectifier K+ channel by intracellular tetraethylammonium in the presence of various alkali metal ions in both the extra- and intracellular solutions. We found that the channel exhibits different degrees of rectification when different alkali metal ions (all at 100 mM) are present in the extra- and intracellular solution. A quantitative analysis shows that an external ion site in the ROMK1 pore binds various alkali metal ions (Na+, K+, Rb+, and Cs+) with different affinities, which can in turn be altered by the binding of different permeating ions at an internal site through a nonelectrostatic mechanism. Consequently, the external site is saturated to a different level under the various ionic conditions. Since rectification is determined by the movement of all energetically coupled ions in the transmembrane electrical field along the pore, different degrees of rectification are observed in various combinations of extra- and intracellular permeant ions. Furthermore, the external and internal ion-binding sites in the ROMK1 pore appear to have different ion selectivity: the external site selects strongly against the smaller Na+, but only modestly among the three larger ions, whereas the internal site interacts quite differently with the larger K+ and Rb+ ions.

Equilibrium geometries, electronic structure and magnetic properties of ConSn (n = 1–12) clusters from density functional calculations

2017 ◽  
Vol 31 (15) ◽  
pp. 1750171 ◽  
Author(s):  
Jing Ya Zhang ◽  
Jin Lv
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Density Of State ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Order Difference ◽  
Electron Density Functional Theory ◽  
External Site ◽  
Equilibrium Geometries ◽  
Stable Structures

Equilibrium geometries, relative stabilities, electronic stabilities and magnetic properties of Co[Formula: see text]Sn ([Formula: see text] = 1–12) clusters have been systematically investigated by using relativistic all-electron density functional theory with generalized gradient approximation. The results indicated that the lowest-energy structures of Co[Formula: see text]Sn ([Formula: see text] = 1–5, 7, 9 and 10) clusters are similar to those of corresponding Co[Formula: see text] clusters. As for Co6Sn, Co8Sn, Co[Formula: see text]Sn and Co[Formula: see text]Sn clusters, the most stable structures give rise to a geometry reconstruction. In the low-lying structures of Co[Formula: see text]Sn ([Formula: see text] = 1–12) clusters, tin impurity prefers to occupy the external site. The second-order difference energy of the ground-state Co[Formula: see text]Sn ([Formula: see text] = 1–12) clusters shows a pronounced odd–even oscillation with the number of Co atoms, and the clusters exhibit higher stability at [Formula: see text] = 5. Compared with corresponding pure Co[Formula: see text] clusters, the total magnetic moment of the Co[Formula: see text]Sn clusters reduces with 1, 3 and 5 [Formula: see text], respectively. The different magnetic changes of the tin doped Co clusters are analyzed in detail based on the magnetism coupling, density of state and hybridization between cobalt and tin atoms.

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