scholarly journals Chloride-ion stimulation of the tonoplast H+-translocating ATPase from Hevea brasiliensis (rubber tree) latex. A dual mechanism

1985 ◽  
Vol 226 (1) ◽  
pp. 85-94 ◽  
Author(s):  
B P Marin ◽  
X Gidrol
Keyword(s):  
Membrane Potential ◽  
Atpase Activity ◽  
Hevea Brasiliensis ◽  
Rubber Tree ◽  
Electrical Potential ◽  
Chloride Ion ◽  
The Other ◽  
Potential Difference ◽  
Dual Mechanism ◽  
Stimulation Of

The effect of Cl- and other anions on the tonoplast H+-translocating ATPase (H+-ATPase) from Hevea brasiliensis (rubber tree) latex was investigated. Cl- and other anions stimulated the ATPase activity of tightly sealed vesicles prepared from Hevea tonoplast, with the following decreasing order of effectiveness: Cl- greater than Br- greater than SO4(2-) greater than NO3-. As indicated by the changes of the protonmotive potential difference, anion stimulation of tonoplast H+-ATPase was caused in part by the ability of these anions to dissipate the electrical potential. This interpretation assumes not a channelling of these anions against a membrane potential, negative-inside, but a modification of the permeability of these ions through the tonoplast membrane. In addition, Cl- and the other anions stimulated the ATPase activity solubilized from the tonoplast membrane. Consequently, the tonoplast H+-pumping ATPase can be considered as an anion-stimulated enzyme. These results are discussed in relation to various models described in the literature for the microsomal H+-ATPase systems claimed as tonoplast entities.

scholarly journals The protonmotive potential difference across the vacuo-lysosomal membrane of Hevea brasiliensis (rubber tree) and its modification by a membrane-bound adenosine triphosphatase

1981 ◽  
Vol 198 (2) ◽  
pp. 365-372 ◽  
Author(s):  
B Marin ◽  
M Marin-Lanza ◽  
E Komor
Keyword(s):  
Membrane Potential ◽  
Hevea Brasiliensis ◽  
Ph Dependence ◽  
Rubber Tree ◽  
Lysosomal Membrane ◽  
Potential Difference ◽  
Experimental Conditions ◽  
Carbonyl Cyanide ◽  
Membrane Bound ◽  
K Concentration

The vacuo-lysosomes of Hevea brasiliensis (rubber tree) constitute a suitable model system for the study of active transport and energization at the level of the membrane of plant vacuoles. The pH gradient (delta pH) and the membrane potential (delta psi) of vacuo-lysosomes were determined by means of the weak base methylamine and the lipophilic cation tetraphenylphosphonium. The values obtained depended strongly on the experimental conditions such as medium pH or K+ concentration. Under experimental conditions, i.e., pH 7.5 outside and low K+, the delta pH amounts to about 0.9 unit, interior acid, and the delta psi to -120 mV, interior negative. The delta psi is presumably caused by the imposed K+ gradient, and the internal acidification might be a consequence of the passive proton inflow along the electric field. This explanation is sustained by the ineffectiveness of carbonyl cyanide p-trifluoromethoxyphenylhydrazone in destroying the delta pH and delta psi, whereas higher K+ concentration decreased both. Under conditions existing in vivo, the membrane potential might be significantly lower. The presence of ATP increased the acidification of the intravesicular space by 0.5pH unit to a delta pH of up to 1.4 and shifts the membrane potential at least 60mV to a more positive value. The change of the protonmotive potential did not occur with ADP; the pH-dependence of the change was identical with the pH-dependence of a vacuo-lysosomal membrane-bound ATPase, and the effect of ATPase was prevented by the presence of the uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone. The change of protonmotive potential difference, brought about by the ATPase, was at least 90 mV. This is evidence that a vacuo-lysosomal ATPase in plants can function as an electrogenic proton pump that transfers protons into the vacuo-lysosomal space.

scholarly journals The control by ΔµH+ of the tonoplast-bound H+-translocating adenosine triphosphatase from rubber-tree (Hevea brasiliensis) latex

1985 ◽  
Vol 229 (2) ◽  
pp. 459-467 ◽  
Author(s):  
B P Marin
Keyword(s):  
Atpase Activity ◽  
Equilibrium State ◽  
Hevea Brasiliensis ◽  
Adenosine Triphosphatase ◽  
Atp Hydrolysis ◽  
Rubber Tree ◽  
The Other ◽  
Proton Gradient ◽  
Electrochemical Proton Gradient ◽  
The Relationship

The relationship between tonoplast-bound ATPase activity and the magnitude of the electrochemical proton gradient has been investigated on tightly sealed vesicles prepared from rubber-tree (Hevea brasiliensis) latex. A variety of methods have been used to modify, either alone or together, the two components of the electrochemical proton gradient (delta mu H+). When the delta pH component was decreased either by titration with (NH4)2SO4 or by addition of protonophores or nigericin in the presence of K+, ATPase activity was stimulated. On the other hand, when the delta psi component was decreased either by addition of lipophilic cations or by addition of valinomycin in the presence of K+, ATPase activity decreased. It is concluded that activity of the tonoplast-bound ATPase is regulated by changes in the electrochemical proton gradient across the tonoplast, so that, once the maximum proton gradient is established across the tonoplast, any perturbation of the equilibrium state should result in the increased rate of ATP hydrolysis as the enzyme attempts to re-establish the initial gradient.

Blood Gas Analysis

2011 ◽  
Author(s):  
Patrick Magee ◽  
Mark Tooley
Keyword(s):  
Electrical Potential ◽  
Physical Principle ◽  
Gas Analysis ◽  
The Other ◽  
Potential Difference ◽  
Ion Concentration ◽  
Blood Gas ◽  
Glass Membrane ◽  
Current Flows ◽  
Ph Electrode

A blood gas machine has electrodes to measure pH, pCO2 and pO2 and often measures Hb and some biochemistry as well [King et al. 2000]. Derived values from such a device include O2 saturation, O2 content, bicarbonate, base excess and total CO2. This is the Clarke electrode described in the previous section on gas analysers and is suitable for both respiratory and blood O2 analysis. A pH unit has been defined in Chapter 1 as. In words, this can be described as ‘the negative logarithm, to base ten, of the hydrogen ion concentration’. The physical principle on which the pH electrode is based depends on the fact that when a membrane separates two solutions of different [H+], a potential difference exists across the membrane. In a pH electrode, such a membrane is usually made of glass and the development of a potential difference between the two solutions is thought to be due to the migration of H+ into the glass matrix. If one solution consists of a standard [H+], the pH of the other solution can be estimated by measurement of the potential difference between them. The glass membrane used is selectively permeable to H+. No current flows in this device, which does not wear out, in contrast to the Clark electrode, in which current does flow and that does need periodic replacement. The pH measurement system is shown diagrammatically in Figure 17.1. It consists of two half cells. In one half it has an Ag/AgCl electrode and in the other a Hg/HgCl2 (calomel) electrode. Each electrode maintains a fixed electrical potential. The Ag/AgCl electrode is surrounded by a buffer solution of known pH, surrounded by the pH sensitive glass. Outside the glass membrane is the test solution, usually blood, whose pH is to be measured. It is the potential difference across the glass, between these two solutions, which is variable. The blood or other solution is separated from the calomel electrode by a porous plug and a potassium chloride salt bridge to minimise KCl diffusion. The potential difference across the system is about 60 mV per unit of pH change at 37◦C.

Stimulation of HCO3- transport in isolated proximal bullfrog duodenum by prostaglandins

1980 ◽  
Vol 239 (3) ◽  
pp. G198-G203 ◽  
Author(s):  
G. Flemstrom
Keyword(s):  
Electrical Potential ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Morphological Examination ◽  
Minimal Concentration ◽  
Dependent Transport ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Stimulation Of

An in vitro preparation of proximal duodenum from the bullfrog transported alkali into the luminal solution (approximately 1 mueq x h-1 x cm-2) and generated a transepithelial electrical potential difference (5-10 mV, lumen negative). Transport was inhibited by 2,4-dinitrophenol (10(-5) M), CN- (5 X 10(-3) M), indomethacin (5 X 10(-5) M), and acetazolamide (5 X 10(-3) M) indicating that metabolism is required. Both alkali transport and the electrical potential difference showed a dose-dependent increase on administration of the prostaglandins E2, 16,16-dimethyl E2, and F2 alpha. The minimal concentration stimulating transport was lower with the E-type prostaglandins (10(-8) M than with F2 alpha (10(-6) M), and the former also produced greater maximal responses. In addition to metabolic-dependent transport of alkali, there was passive transmucosal migration of HCO3-, amounting to approximately 40% of basal (unstimulated) transport and sensitive to variation of the transmucosal hydrostatic pressure. Morphological examination showed that the preparation is devoid of Brunner glands. Stimulation of duodenal epithelial HCO3- transport by prostaglandins may contribute to their previously demonstrated ability to prevent duodenal ulceration.

scholarly journals AMP-dependence of the cyanide-insensitive pathway in the respiratory chain of Paramecium tetraurelia

1984 ◽  
Vol 220 (3) ◽  
pp. 787-794 ◽  
Author(s):  
J Doussière ◽  
P V Vignais
Keyword(s):  
Membrane Potential ◽  
Cyclic Amp ◽  
Oxidase Activity ◽  
Amine Oxide ◽  
The Other ◽  
Paramecium Tetraurelia ◽  
Quinol Oxidase ◽  
Ubiquinol Oxidase ◽  
Irreversible Inhibition ◽  
Stimulation Of

The AMP-dependent stimulation of the cyanide-insensitive respiration of Paramecium mitochondria was investigated. The nucleotides exhibiting a stimulatory effect on the cyanide-insensitive oxidation of pyruvate (+ malate) in a medium supplemented with EDTA or carboxyatractyloside were, in decreasing order of efficiency, AMP, GMP, IMP, UMP and TMP. On the other hand, ADP, ATP and cyclic AMP were ineffective. In the presence of carboxyatractyloside, addition of AMP to Paramecium mitochondria incubated with pyruvate (+malate) led to an increase in membrane potential. In the absence of light, the photoactivable derivative of AMP, 3′-[4-[N-(4-azido-2-nitrophenyl)amino]butyryl]-AMP (NAP4-AMP) added to Paramecium mitochondria opposed the stimulatory effect of AMP on the cyanide-insensitive respiration; the Ki for NAP4-AMP was much lower than the Km for AMP, 0.2 microM compared with 120 microM. The ADP-stimulated respiration was not affected. Photoirradiation of Paramecium mitochondria in the presence of NAP4-AMP resulted in irreversible inhibition of the AMP-stimulated cyanide-insensitive respiration. No effect on the ADP-stimulated respiration was observed. A heatlabile cyanide-insensitive ubiquinol oxidase was extracted from Paramecium mitochondria with the detergent NN-dimethyl-N-(3-laurylamidopropyl)amine oxide. The quinol oxidase activity was slightly stimulated by AMP.

scholarly journals Electrical Potential Difference Measurements in Perfused Single Proximal Tubules of Necturus Kidney

1961 ◽  
Vol 44 (4) ◽  
pp. 679-687 ◽  
Author(s):  
Guillermo Whittembury ◽  
Erich E. Windhager
Keyword(s):  
Electrical Potential ◽  
Proximal Tubules ◽  
The Other ◽  
Potential Difference ◽  
Stopped Flow ◽  
Electrical Potential Difference ◽  
Necturus Maculosus ◽  
Other Hand ◽  
Glomerular Filtrate

Transtubular and peritubular face electrical potential differences (P.D.) of the proximal tubules of the kidney of the amphibian Necturus maculosus have been measured in situ. These measurements have been carried out both under normal conditions, when the tubular fluid originates in the glomerular filtrate, and under conditions when the composition of the tubular fluid has been altered using the stopped flow microperfusion technique. Under normal conditions the transtubular potential difference is 20 mv. (lumen-negative) and the P.D. across the peritubular face is 74 mv. (cell-negative). The P.D. across the luminal face is thus 54 mv. (cell-negative). This electrical asymmetry is not influenced by replacing the normal tubular fluid by NaCl, NaCl + mannitol, or by alteration in the intraluminal pH from 7 to 4. On the other hand, replacement of Na by K or choline and the addition of small amounts of DNP to the perfusate diminish this asymmetry.

scholarly journals Modulation ofβ-Cell Ouabain-SensitiveR86b+Influx (Na+/k+Pump) by D-Glucose, Glibenclamide or Diazoxide

2000 ◽  
Vol 1 (4) ◽  
pp. 265-274 ◽  
Author(s):  
Adrian Elmi ◽  
Lars-ÅKe Idahl ◽  
Janove Sehlin
Keyword(s):  
Atpase Activity ◽  
Direct Effect ◽  
Mechanism Of Action ◽  
The Other ◽  
Pump Function ◽  
Other Hand ◽  
Insulin Secretagogues ◽  
Pre Treatment ◽  
Effect Of Glucose ◽  
Stimulation Of

The activity of theβ-cellNa+/k+pump was studied by using ouabain-sensitive (lmM ouabain)R86b+influx inβ-cell-rich islets of Umeå-ob/obmice as an indicator of the pump function. The present results show that the stimulatory effect of glucose on ouabain-sensitiveR86b+influx reached its approximate maximum at 5mM glucose. Pre-treatment of the islets with 20mM glucose for 60 min strongly reduced the glucose-induced stimulation of theNa+/k+pump. Pre-treatment (60 or 180 min) of islets at 0mM glucose, on the other hand, did not affect the magnitude of the glucose-induced stimulation ofR86b+influx dunng the subsequent 5-min incubation. Glibenclamide stimulated the ouabain-sensitiveR86b+uptake in the same manner as glucose. The stimulatory effect, showed its apparent maximum at 0.5μM. Pre-treatment (60 min) of islets with 1μM glibenclamide did not reduce the subsequent stimulation of the ouabain-sensitiveR86b+influx. The stimulatory effect of glibenclamide and D-glucose were not .additive, suggesting that they may have the same mechanism of action. No direct effect of glibenclamide (0.01-1μM) was observed on theNa+/k+ATPase activity in homogenates of islets. Diazoxide (0.4mM) inhibited theNa+/k+pump. This effect was sustained even after 60 min of pre-treatment of islets with 0.4mM diazoxide. The stimulatory effect of glibenclamide and D-glucose were abolished by diazoxide. It is concluded that nutrient as well as non-nutrient insulin secretagogues activate theNa+/k+pump, probably as part of the membrane repolarisation process.

scholarly journals Evaluasi 18 primer SSR untuk pengembangan sidikjari DNA tanaman karet (Hevea brasiliensis Muell. Arg.) Evaluation of 18 SSR primers to develop DNA fingerprint of rubber tree (Hevea brasiliensis Muell. Arg.)

2016 ◽  
Vol 82 (2) ◽  
Author(s):  
Asmini BUDIANI ◽  
Sekar WOELAN ◽  
Hayati MINARSIH ◽  
. NUHAIMI-HARIS ◽  
Riza Arief PUTRANTO
Keyword(s):  
Molecular Markers ◽  
Hevea Brasiliensis ◽  
Rubber Tree ◽  
The Other ◽  
Dna Fingerprint ◽  
Amplification Product ◽  
Pcr Product ◽  
Ssr Primers ◽  
Pcr Products ◽  
Genomic Dnas

Abstract Breeding program of rubber tree to produce elite clones is hampered by the length of selection cycles. On the other hand, attempts to increase production by extensification of the plantation area is also facing a problem from the availability of the rootstock, causing the occurence of fake clones without any information of their origin. Therefore, the availability of molecular markers to be used as DNA fingerprint of rubber tree clones is needed. This will help the breeder to shorten the length of selection program and to identify the purity of the clone. This research was aimed to evaluate 18 SSR primer pairs that had been published to identify 17 rubber clones. Pure genomic DNAs were isolated from 17 clones, followed by experiment to optimize annealing tempe-rature for each primer to obtain the best amplification product. Initially, the PCR product was run in both the agarose and polyacrylamide gels. However, the analysis of all PCR products were then conducted on SDS polyacrylamide gel, since this gel can separate DNA fragments with only a few bases differences. The results showed that 14 clones have been identified specifically using 11 primers. Four out of 18 primer pairs used could identify 12 rubber tree clones, which are PR 107, PR 261, SP 217, PB 330, PB 340, IRR 5, IRR 112, IRR 118, IRR 220, GT 1, BPM 101 and RRIM 712. Each clone can be distinguished from each other using only one primer pair. Identification of the other tree clones (PB 5/51, PB 260, and RRIC 110) has to be conducted by combining the several PCR products using different primer pairs. Although these results showed that SSR markers had high potential to be used as DNA fingerprint on rubber tree clones, the set of the primer pairs should be tested among other clones, as well as other SSR primers should be tested to identify the clones which could not be identified using the 18 primer pairs in this experiment.Abstrak Pemuliaan tanaman karet untuk menghasilkan klon-klon unggul baru menghadapi masalah lamanya siklus seleksi. Di sisi lain, upaya peningkatan produksi melalui pembukaan lahan baru, juga terkendala oleh ketersediaan bibit, yang memicu beredarnya bibit palsu, yang umumnya tidak jelas asal usulnya. Oleh karena itu, diperlukan ketersediaan marka yang dapat digunakan sebagai sidikjari DNA bagi klon-klon tanaman karet yang ada, sehingga dapat membantu mempercepat proses seleksi dan mengetahui kemurnian bibit. Penelitian ini bertujuan untuk mengevaluasi 18 primer SSR yang telah dipublikasikan untuk mengidentifikasi 17 klon karet. DNA yang murni diisolasi dari 17 klon, kemudian dilakukan optimasi suhu annealing untuk setiap jenis primer agar diperoleh hasil amplifikasi terbaik.  Pada awal percobaan hasil PCR dicek pada gel agarosa dan gel poliakrilamida, namun analisis untuk seluruh hasil PCR dilakukan pada gel SDS poliakrilamid, karena gel ini secara nyata dapat memisahkan fragmen DNA yang hanya berbeda beberapa basa. Hasil percobaan menunjukkan bahwa 14 klon dapat diidentifikasi secara spesifik menggunakan 11 primer. Empat dari 18 pasang primer yang diuji dapat mengidentifikasi 12 klon yang dianalisis, yaitu PR 107, PR 261, SP 217, PB 330, PB 340,. IRR 5, IRR 112, IRR 118, IRR 220, GT 1, BPM 101 dan RRIM 712. Masing-maing klon tersebut dapat dibedakan dari klon lainnya hanya dengan menggunakan satu jenis primer. Sedangkan identifikasi tiga klon lainnya (PB 5/51, PB 260, dan RRIC110) harus dilakukan dengan menggabungkan hasil PCR menggunakan beberapa primer. Meskipun hasil percobaan ini menunjukkan bahwa marka SSR sangat berpotensi untuk digunakan sebagai sidikjari DNA klon-klon karet, namun primer yang sama perlu diuji untuk klon-klon lainnya. Demikian pula primer lain perlu diuji untuk mengidentifikasi klon-klon yang belum teridentifikasi menggunakan 18 primer dalam penelitian ini.

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