scholarly journals ROLE OF BIOLOGICAL PROCESSES DURING MANGANESE REMOVAL FROM UNDERGROUND WATER

2016 ◽  
Vol 1 ◽  
pp. 61-67
Author(s):  
Oleksandr Kravchenko
Keyword(s):  
Significant Role ◽  
Underground Water ◽  
Biological Processes ◽  
High Concentration ◽  
Manganese Removal ◽  
Low Concentrations ◽  
Physico Chemical ◽  
High Level ◽  
Manganese Compounds

This article briefly presents the results of the effect of oxidants during filtration of groundwater with high level of manganese compounds. Significant role of biological processes along with physico-chemical at demanganation of groundwater has been noticed. It has been studied that biological processes are dominated in low concentrations of oxidants. At high concentration of disinfectant the role of physico-chemical processes begin to dominate. Thus, there is a significant role of microorganisms in physico-chemical process of manganese removal. Obtained results showed that the oxygen is more efficient oxidizer than sodium hypochlorite for compounds of manganese presented in groundwater.

Induction of Rishitin and Lubimin Synthesis in Potato Tuber Slices by Non-Specific Elicitors — Role of Gene Derepression

1979 ◽  
Vol 42 (6) ◽  
pp. 512-518 ◽  
Author(s):  
A. S. CHEEMA ◽  
N. F. HAARD
Keyword(s):  
Potato Tuber ◽  
Mrna Translation ◽  
Metabolic Inhibitors ◽  
Protein Synthesis Inhibitors ◽  
High Concentration ◽  
Low Concentrations ◽  
Translation Block ◽  
Heavy Metal Salts ◽  
Stress Metabolites

The stress metabolites rishitin and lubimin accumulate at relatively low concentrations (5–20 ppm) in potato tuber slices subjected to various cell-disruptive treatments including heavy metal salts, sulfhydryl reagents, metabolic inhibitors, detergents, ultraviolet light and lysosomal enzymes. Cold-stored (4 C) tubers are more disposed to terpene accumulation than freshly harvested, 25-C stored and conditioned potatoes. Various inhibitors of DNA transcription and mRNA translation block terpene induction by non-specific elicitors when applied at sufficiently high concentration. However. various protein synthesis inhibitors were shown to be potent elicitors of terpene accumulation when applied at lower concentration. Actinomycin D (25 μg/ml) treatment of discs for 30 min elicits higher levels of rishitin than results from Phytophthora infestans interaction with potato (> 100 ppm). A mechanism for terpene induction based on derepression of “stress metabolite DNA” is proposed to explain the experimental data.

Influence of Location of a Fluorescent Zinc Probe in Brain Slices on Its Response to Synaptic Activation

2006 ◽  
Vol 95 (3) ◽  
pp. 1949-1956 ◽  
Author(s):  
Alan R. Kay ◽  
Katalin Tóth
Keyword(s):  
Fluorescent Probes ◽  
Synaptic Vesicles ◽  
Hippocampal Slices ◽  
Brain Slices ◽  
Live Cells ◽  
High Concentration ◽  
Low Concentrations ◽  
Powerful Approach ◽  
Precise Role

The precise role of the high concentration of ionic zinc found in the synaptic vesicles of certain glutamatergic terminals is unknown. Fluorescent probes with their ability to detect ions at low concentrations provide a powerful approach to monitoring cellular Zn2+ levels. In the last few years, a number of fluorescent probes (indicators) have been synthesized that can be used to visualize Zn2+ in live cells. The interpretation of data gathered using such probes depends crucially on the location of the probe. Using acutely prepared hippocampal slices, we provide evidence that the Zn2+ probes, ZnAF-2 and ZP4, are membrane permeant and are able to pass into synaptic vesicles. In addition, we show that changes in fluorescence of the Zn2+ probes can be used to monitor presynaptic activity; however, these changes are inconsistent with Zn2+ release.

Functional Role of Ca2+ Currents in Graded and Spike-Mediated Synaptic Transmission Between Leech Heart Interneurons

1997 ◽  
Vol 77 (4) ◽  
pp. 1779-1794 ◽  
Author(s):  
Jin Lu ◽  
John F. Dalton ◽  
Darrell R. Stokes ◽  
Ronald L. Calabrese
Keyword(s):  
Synaptic Transmission ◽  
Voltage Clamp ◽  
Functional Role ◽  
Inactivation Kinetics ◽  
High Concentration ◽  
Outward Currents ◽  
Low Concentrations ◽  
Low Threshold ◽  
Kinetics Of

Lu, Jin, John F. Dalton, IV, Darrell R. Stokes, and Ronald L. Calabrese. Functional role of Ca2+ currents in graded and spike-mediated synaptic trnasmission between leech heart interneurons. J. Neurophysiol. 77: 1779–1794, 1997. We used intracellular recording and single electrode voltage-clamp techniques to explore Ca2+ currents and their relation to graded and spike-mediated synaptic transmissions in leech heart interneurons. Low-threshold Ca2+ currents (activation begins below −50 mV) consist of a rapidly inactivating component ( I CaF) and a slowly inactivating component ( I CaS). The apparent inactivation kinetics of I CaF appears to be influenced by Ca2+; both the substitution of Ca2+ (5 mM) with Ba2+ (5 mM) in the saline and the intracellular injection of the rapid Ca2+ chelator, bis-( o-aminophenoxy)- N,N,N′,N′-tetraacetic acid (BAPTA), from the recording microelectrode, significantly increase its apparent inactivation time constant. The use of saline with a high concentration of Ba2+ (37.5 mM) permitted exploration of divalent ion currents over a broader activation range, by acting as an effective charge carrier and significantly blocking outward currents. Ramp and pulse voltage-clamp protocols both reveal a rapidly activating and inactivating Ba2+ current ( I BaF) and a less rapidly activating and slowly inactivating Ba2+ current with a broad activation range ( I BaS). Low concentrations of Cd2+ (100–150 μM) selectively block I BaS, without significantly diminishing I BaF. The current that remains in Cd2+ lacks the characteristic delayed activation peak of I BaS and inactivates with two distinct time constants. I BaF appears to correspond to a combination of I CaF and I CaS, i.e., to low-threshold Ca2+ currents, that can be described as T-like. I BaS appears to correspond to a Ca2+ current with a broad activation range, which can be described as L-like. Cd2+ (100 μM) selectively blocks spike-mediated synaptic transmission between heart interneurons without significantly interfering with low-threshold Ca2+ currents and plateau formation in or graded synaptic transmission between heart interneurons. Blockade of spike-mediated synaptic transmission between reciprocally inhibitory heart interneurons with Cd2+ (150 μM), in otherwise normal saline, prevents the expression of normal oscillations (during which activity in the two neurons consists of alternating bursts), so that the neurons fire tonically. We conclude that graded and spike-mediated synaptic transmission may be relatively independent processes in heart interneurons that are controlled predominantly by different Ca2+ currents. Moreover, spike-mediated synaptic inhibition appears to be required for normal oscillation in these neurons.

scholarly journals Regulation of δ-aminolaevulinic acid synthesis and protochlorophyllide regeneration in the leaves of dark-grown barley (Hordeum vulgare) seedlings

1984 ◽  
Vol 222 (2) ◽  
pp. 419-426 ◽  
Author(s):  
A K Stobart ◽  
I Ameen-Bukhari
Keyword(s):  
Hordeum Vulgare ◽  
Acid Synthesis ◽  
Active Species ◽  
Light Treatment ◽  
High Concentration ◽  
Aminolaevulinic Acid ◽  
Low Concentrations ◽  
Sufficient Energy ◽  
Close Relationship ◽  
High Level

Laevulinic acid (Lev) was used to control the rate of protocholorophyllide (PChl) regeneration in the leaves of dark-grown seedlings of barley (Hordeum vulgare) after a brief light treatment. In the leaves given Lev, at concentrations that severely block the resynthesis of protochlorophyllide, there was a massive overproduction of delta-aminolaevulinic acid (AmLev) that was well in excess of that required for the regeneration of PChl observed in the control leaves. Lev, at low concentrations, slightly delayed regeneration and held up, rather than inhibited, the utilization of the AmLev, which accumulated in the tissues. The overproduction and uncontrolled formation of AmLev also occurred in dark-grown leaves treated with a high concentration of Lev and given a light treatment of just sufficient energy to photoreduce only small quantities of the endogenous PChl. Experiments in which a high level of free PChl was induced by incubating the leaves in AmLev indicated that the active species of PChl was that associated with, and bound to, the PChl reductase protein. The results strongly demonstrate a close relationship between the PChl-protein complex and the ability of the leaves to synthesize AmLev.

scholarly journals Ca2+ transport by the luminal membrane of the distal nephron: action and interaction of protein kinases A and C

1997 ◽  
Vol 328 (2) ◽  
pp. 371-375 ◽  
Author(s):  
Georges HILAL ◽  
David CLAVEAU ◽  
Marie LECLERC ◽  
Michèle G. BRUNETTE
Keyword(s):  
Phospholipase C ◽  
Protein Kinases ◽  
Distal Tubule ◽  
High Concentration ◽  
Protein Kinase C Inhibitors ◽  
Luminal Membrane ◽  
Low Concentrations ◽  
Distal Tubules ◽  
High Concentrations

We previously reported that parathyroid hormone and calcitonin increase Ca2+ uptake by purified distal luminal membranes. This effect is mimicked by high concentrations of cAMP. However, both hormones stimulate adenylate cyclase and phospholipase C. The purpose of the present study was to investigate the role of the phospholipase C pathway in the hormone action, and the interrelationship between the two messengers. Distal tubules from rabbit kidneys were incubated with dibutyryl cAMP (dbcAMP) or PMA, or both, and Ca2+ uptake by purified luminal membranes was measured by the rapid filtration technique. Incubation of the distal tubules with 1 mM dbcAMP significantly increased Ca2+ transport by the luminal membranes. A dose-response curve showed a half-maximal stimulation with 0.82 mM dbcAMP. In contrast, treatment of the tubules with 10 nM, 100 nM or 1 μM PMA did not influence Ca2+ uptake by these membranes. However, the addition of 100 nM PMA to low concentrations of dbcAMP strongly increased this uptake. The presence of cAMP or protein kinase C inhibitors prevented the effects of either a high concentration of dbcAMP alone or a low concentration of dbcAMP combined with 100 nM PMA. Our laboratory has already reported that Ca2+ uptake by the distal luminal membranes displays two-component kinetics. dbcAMP increased the Vmax of the low-affinity component, whereas a combination of the two messengers stimulated the Vmax of both the low- and high-affinity components. From these results, we conclude that: (1) in the distal tubule cells, activation of both protein kinases A and C is necessary for the stimulation of Ca2+ transport by the luminal membrane; (2) the combined effect of protein kinases A and C involves both components of the Ca2+-transport kinetics.

scholarly journals Salicylic Acid Stimulates Antioxidant Defense and Osmolyte Metabolism to Alleviate Oxidative Stress in Watermelons under Excess Boron

Plants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 724 ◽  
Author(s):  
Mohamed Moustafa-Farag ◽  
Heba I. Mohamed ◽  
Ahmed Mahmoud ◽  
Amr Elkelish ◽  
Amarendra N. Misra ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Antioxidant Defense ◽  
Crop Productivity ◽  
Nutrient Concentrations ◽  
High Concentration ◽  
Morphological Criteria ◽  
Biochemical Level ◽  
Carbon Dioxide Co2 ◽  
High Level

Boron (B) is a microelement required in vascular plants at a high concentration that produces excess boron and toxicity in many crops. B stress occurs widely and limits plant growth and crop productivity worldwide. Salicylic acid (SA) is an essential hormone in plants and is a phenolic compound. The goal of this work is to explore the role of SA in the alleviation of excess B (10 mg L−1) in watermelon plants at a morphological and biochemical level. Excess boron altered the nutrient concentrations and caused a significant reduction in morphological criteria; chlorophyll a, b, and carotenoids; net photosynthetic rate; and the stomatal conductance and transpiration rate of watermelon seedlings, while intercellular carbon dioxide (CO2) was significantly increased compared to the control plants (0.5 mg L−1 B). Furthermore, excess boron accelerated the generation of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2) and induced cellular oxidative injury. The application of exogenous SA significantly increased chlorophyll and carotenoid contents in plants exposed to excess B (10 mg L−1), in line with the role of SA in alleviating chlorosis caused by B stress. Exogenously applied SA promoted photosynthesis and, consequently, biomass production in watermelon seedlings treated with a high level of B (10 mg L−1) by reducing B accumulation, lipid peroxidation, and the generation of H2O2, while significantly increasing levels of the most reactive ROS, OH−. SA also activated antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) and protected the seedlings from an ROS induced cellular burst. In conclusion, SA can be used to alleviate the adverse effects of excess boron.

scholarly journals The Anti-Methicillin-Resistant Staphylococcus aureus Quinolone WCK 771 Has Potent Activity against Sequentially Selected Mutants, Has a Narrow Mutant Selection Window against Quinolone-Resistant Staphylococcus aureus, and Preferentially Targets DNA Gyrase

2006 ◽  
Vol 50 (11) ◽  
pp. 3568-3579 ◽  
Author(s):  
Sachin S. Bhagwat ◽  
Lakshmi A. Mundkur ◽  
Shrikant V. Gupte ◽  
Mahesh V. Patel ◽  
Habil F. Khorakiwala
Keyword(s):  
Staphylococcus Aureus ◽  
Dna Gyrase ◽  
Primary Target ◽  
Topoisomerase Iv ◽  
Mutant Selection ◽  
Low Concentrations ◽  
Selection Window ◽  
High Level ◽  
The Impact

ABSTRACT WCK 771 is a broad-spectrum fluoroquinolone with enhanced activity against quinolone-resistant staphylococci. To understand the impact of the target-level interactions of WCK 771 on its antistaphylococcal pharmacodynamic properties, we determined the MICs for genetically defined mutants and studied the mutant prevention concentrations (MPCs), the frequency of mutation, and the cidality against the wild type and double mutants. There was a twofold increase in the MICs of WCK 771 for single gyrA mutants, indicating that DNA gyrase is its primary target. All first- and second-step mutants selected by WCK 771 revealed gyrA and grlA mutations, respectively. The MICs of WCK 771 and clinafloxacin were found to be superior to those of other quinolones against strains with double and triple mutations. WCK 771 was also cidal for high-density double mutants at low concentrations. WCK 771 and clinafloxacin showed narrow mutant selection windows compared to those of the other quinolones. Against a panel of 50 high-level quinolone-resistant clinical isolates of staphylococci (ciprofloxacin MIC ≥ 16 μg/ml), the WCK 771 MPCs were ≤2 μg/ml for 68% of the strains and ≤4 μg/ml for 28% of the strains. Our results demonstrate that gyrA is the primary target of WCK 771 and that it has pharmacodynamic properties remarkably different from those of quinolones with dual targets (garenoxacin and moxifloxacin) and topoisomerase IV-specific quinolones (trovafloxacin). WCK 771 displayed an activity profile comparable to that of clinafloxacin, a dual-acting quinolone with a high affinity to DNA gyrase. Overall, the findings signify the key role of DNA gyrase in determining the optimal antistaphylococcal features of quinolones.

The Role of the City in Higher Education Internationalization: French and Russian Regional Context

2021 ◽  
pp. 236-250
Author(s):  
Irina A. Skalaban ◽  
◽  
Lyudmila A. Osmuk ◽  
Anastasia M. Pogorelskaya ◽  
Michele Debrenne ◽  
...  
Keyword(s):  
Higher Education ◽  
International Students ◽  
High Concentration ◽  
Regional Universities ◽  
High Level ◽  
University City ◽  
The University ◽  
The City ◽  
Higher Education Internationalization

The competition for international students is growing among both different countries and universities within one country. Regional universities in Russia, meaning those outside Moscow and Saint Petersburg, try to use internationalization in order to contribute to the development of their regions. However, a high level of academic mobility is usually ensured by comfortable living conditions that both the university and the city the university is situated in provide. The article covers the role of the city as the factor that may contribute to higher education internationalization. The research is based on the perception of certain university cities that international students living there have. Taking into account the ideas of Machlup, Florida, and Castells, the authors consider universities the key actors of university cities development in Siberia. Thus, two Siberian university cities included in the QS Best Student Cities ranking, namely, Tomsk and Novosibirsk, were considered in the research. To evaluate their role in international students’ choice for their universities, international students in Tomsk and Novosibirsk universities were interviewed during 2018-2020. To compare the results with the international dimension of higher education internationalization, Russian students studying in France were also interviewed. As a result, the criteria of the university choice were determined that are connected with the university city characteristics. The latter include security considerations, cultural diversity and social environment tolerance, aesthetic attractiveness of the city and its sightseeing opportunities, developed transportation system, high concentration of international students, open and accessible communicative environment. However, the criteria international students chose Siberian university cities for included lower prices for education and lower living costs. The main disadvantage is the lack of comfortable communication zones that do not depend on climate. The priorities of international students in large and small university cities turned out to differ: the latter tend to value the quality of university and the city’s historical values as well as personified relations with the locals more. Comparing the opinion of Russian and international students on significant criteria of university cities, the authors found out that international students were less critical to such characteristics of Tomsk and Novosibirsk as security, tolerance and accessibility for disabled people. However, international students were more critical to the number of students in the city. Thus, the creation of comfortable and attractive conditions for international students is the common responsibility of the university, the city and the region.

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