The role of Na+ in membrane transport and respiration in the marine bacterium Deleya aesta 134

1991 ◽  
Vol 37 (6) ◽  
pp. 433-439 ◽  
Author(s):  
Marc Berthelet ◽  
Robert A. MacLeod
Keyword(s):  
Membrane Transport ◽  
Maximum Rate ◽  
Marine Bacterium ◽  
Transport Systems ◽  
Intact Cells ◽  
Effective Competition ◽  
Glucose Accumulation ◽  
Quinone Acceptor ◽  
The Relationship

Deleya aesta required Na+ for the uptake of 8 of 11 metabolites tested; the other three were transported at low rates in the absence of Na+ but at much higher rates in its presence. The optimal concentration of Na+ for maximum rate of transport of all the metabolites was 200 to 300 mM. Higher concentrations added as NaCl inhibited transport to the same extent as equiosomolar concentrations of other salts and sucrose. Li+ but not K+ could replace Na+ for the uptake of some metabolites but was only one-half as effective. Competition studies indicated that a number of different transport systems were involved in uptake. Inhibitor studies of succinate, L-alanine, and D-glucose accumulation (the last in both the presence and absence of Na+) suggested that for each a membrane potential was required. The relationship between rates of transport and oxidation of succinate by intact cells at various Na+ concentrations indicated that the Na+ requirement for oxidation reflected the Na+ requirement for transport. For D-glucose, the relationship was more complex, sinced over a narrow, low concentration range, Na+ inhibited respiration but not transport. Evidence for the presence in D. aesta 134 of a Na+-activated NADH–quinone acceptor oxidoreductase was obtained. Key words: Deleya aesta, marine bacteria, sodium, membrane transport, respiration.

Relationship of the Escherichia coli TrkA System of Potassium Ion Uptake with the F0F1-ATPase Under Growth Conditions Without Anaerobic or Aerobic Respiration

1998 ◽  
Vol 18 (3) ◽  
pp. 143-154 ◽  
Author(s):  
Armen Trchounian ◽  
Yelena Ohanjanyan ◽  
Karine Bagramyan ◽  
Vitya Vardanian ◽  
Eleonora Zakharyan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Conditions ◽  
Transport Systems ◽  
Aerobic Respiration ◽  
Anaerobic Conditions ◽  
Intact Cells ◽  
Potassium Ion Uptake ◽  
Relationship Of ◽  
The Relationship

K+ uptake by the Escherichia coli TrkA system is unusual in that it requires both ATP and ΔμH; a relation withH+ circulation through the membrane is thereforesuggested. The relationship of this system with the F0F1-ATPase was studied in intact cells grownunder different conditions. A significant increase of the N,N'-dicyclohexylcarbodiimide(DCCD)-inhibitedH+ efflux through the F0F1 by 5 mMK+, but not by Na+ added into thepotassium-free medium was revealed only in fermenting wild-type orparent cells, that were grown under anaerobic conditions withoutanaerobic or aerobic respiration and with the production of H2. Such an increase disappeared in the Δunc or the trkA mutants that have alteredF0F1 or defective TrkA, respectively. This finding indicates a closed relationship between TrkA andF0F1, with these transport systems beingassociated in a single mechanism that functions as an ATP-driven H+–K+-exchanging pump. ADCCD-inhibited H+–K+-exchangethrough these systems with the fixed stoichiometry of H+and K+ fluxes(2H+/K+) and a higherK+ gradient between the cytoplasm and the externalmedium were also found in these bacteria. They were not observed incells cultured under anaerobic conditions in the presence of nitrate orunder aerobic conditions with respiration and without production of H2. The role of anaerobic or aerobic respiration as adeterminant of the relationship of the TrkA with the F0F1 is postulated. Moreover, an increase of DCCD-inhibited H+ efflux by added K+, aswell as the characteristics of DCCD-sensitiveH+–K+-exchange found in a parentstrain, were lost in the arcA mutant with a defective Arc system, suggesting a repression of enzymes in respiratorypathways. In addition, K+ influx in the latest mutantwas not markedly changed by valinomycin or with temperature. The arcA gene product or the Arc system is proposed to beimplicated in the regulation of the relationship between TrkA and F0F1.

scholarly journals Biochemical Studies on Active Transport

1968 ◽  
Vol 52 (1) ◽  
pp. 279-295 ◽  
Author(s):  
Arthur B. Pardee
Keyword(s):  
Active Transport ◽  
Cell Function ◽  
Specific Protein ◽  
Transport Systems ◽  
Initial State ◽  
Intact Cells ◽  
The Past ◽  
Biochemical Studies ◽  
Active Transport Process

The active transport process, so important in cell function, has been studied in the past with intact cells. Models which have arisen from this work all depend on: first, a specific protein to recognize the substrate; second, translocation of the substrate across the cell membrane; third, release of substrate within the cell and restoration of the system to its initial state. These steps are adequate for facilitated transport, but in active transport an energy input is required to maintain a concentration gradient. Parts of transport systems have been isolated recently. A protein which specifically recognizes ß-galactosides has been partially purified. In another case, a protein that appears to be the recognition part of the sulfate transport system of Salmonella typhimurium has been crystallized, and many of its properties have been described. The role of this protein in recognition and in translocation is discussed. Also proteins that phosphorylate a variety of sugars as they enter the cell's interior provide a mechanism for concentrating sugars as their phosphates, against a gradient.

Energy coupling to K+ transport in a marine bacterium

1980 ◽  
Vol 58 (10) ◽  
pp. 1206-1214 ◽  
Author(s):  
Edward G. Sedgwick ◽  
Robert A. MacLeod
Keyword(s):  
Driving Force ◽  
Maximum Rate ◽  
Marine Bacterium ◽  
Energy Coupling ◽  
Strictly Aerobic ◽  
Proton Release ◽  
Anaerobic Conditions ◽  
Intact Cells ◽  
Absorbing Material ◽  
K Transport

Cells of the marine bacterium Alteromonas haloplanktis 214 ATCC 19855 (previously referred to as marine pseudomonad B-16) were depleted of K+ by washing with 0.1 M MgSO4. Washing with 0.05 M MgSO4 lowered the Vmax for K+ transport compared with washing with 0.1 M but did not change the Km, while washing with lower concentrations of MgSO4 caused loss of ultraviolet-absorbing material from the cells. K+ uptake was a strictly aerobic process and was accompanied by proton release. When an anaerobic suspension of cells was added to incubation mixtures containing increasing amounts of O2, intracellular ATP concentrations increased as the O2 concentration increased and reached near maximum values before K+ transport began. The O2 concentration initiating K+ transport caused transport to proceed at its maximum rate. For these experiments A. haloplanktis was depleted of ATP by incubating under anaerobic conditions. Incubating with either N′,N′-dicyclohexyl carbodiimide (DCCD) or arsenate failed to deplete intact cells of ATP or prevent K+ transport. The inhibitory activity of DCCD for ATPase in membrane preparations was higher at 5 mM than at other MgSO4 concentrations and increased with time. Cyanide and the uncoupling agents tetrachlorosalicylanide (TCS) and carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP) prevented K+ uptake while TCS and FCCP though not cyanide caused K+ to be released from K+-containing cells. It is concluded that the driving force for K+ transport in these cells is likely to be the membrane potential and that K+ transport may be gated.

scholarly journals The Role of Culture in Urban Travel Patterns: Quantitative Analyses of Urban Areas Based on Hofstede’s Culture Dimensions

2019 ◽  
Vol 8 (8) ◽  
pp. 227 ◽  
Author(s):  
Ali Enes Dingil ◽  
Federico Rupi ◽  
Joerg Schweizer ◽  
Zaneta Stasiskiene ◽  
Kasra Aalipour
Keyword(s):  
Public Transportation ◽  
Urban Areas ◽  
Urban Transport ◽  
Transport Systems ◽  
Travel Patterns ◽  
Urban Travel ◽  
Culture Dimensions ◽  
Per Capita ◽  
The Relationship

Introduction—culture is an interpretation code of societies, which may explain common preferences in a place. Prediction of alternative transport systems, which could be adopted in a city at peace can help urban transport planners and policy makers adjust urban environments in a more sustainable manner. This paper attempts to investigate the role of Hofstede’s culture dimensions (HCD) on urban travel patterns in 87 urban areas and 41 countries. Analysis—this is the first, systematic analysis investigating the effect of culture on urban travel patterns with open source data from different urban areas around the world. The relationship between HCD and some urban travel patterns such as mode choices (individual transportation and public transportation), car ownership, and infrastructure accessibility (road infrastructure per capita) was demonstrated. In addition, the relationship between culture and some demographic indicators (population density and GDP per capita) closely associated with travel choices are checked. The relations between indicators were identified through correlations and regression models, and calibrated to quantify the relation between indicators. Results and Conclusions—good correlation values between Hofstede’s fundamental culture dimension: individualism/collectivism (IND/COL) and urban travel patterns were demonstrated with a reasonably good fit. The analysis showed that countries with higher individualism build more individualistic transport-related environments, which in turn result in more driving. On the other hand, collective nations tend to use more public transportation. There is significant evidence that, in the case of nations, an increase in tree culture dimensions: collectivism, uncertainty, and masculinity, results in greater usage of public transport.

scholarly journals Cellular aspects of folate and antifolate membrane transport.

2000 ◽  
Vol 47 (3) ◽  
pp. 735-749 ◽  
Author(s):  
A Brzezińska ◽  
P Wińska ◽  
M Balińska
Keyword(s):  
Amino Acids ◽  
Membrane Transport ◽  
Physiological Role ◽  
Cancer Development ◽  
Transport Systems ◽  
Transport Activity ◽  
Neoplastic Cells ◽  
Folate Receptors

Folates--one carbon carriers--take part in the metabolism of purine, thymidylate and some amino acids. Internalization of these compounds employs several mechanisms of transport systems. Reduced folate carriers and folate receptors play the most important role in this process. The physiological role of these molecules in normal and neoplastic cells is described regarding changes in transport activity and connection of transport systems with resistance to antifolates and cancer development.

scholarly journals Novel Pathway for Arsenic Detoxification in the Legume Symbiont Sinorhizobium meliloti

2005 ◽  
Vol 187 (20) ◽  
pp. 6991-6997 ◽  
Author(s):  
Hung-Chi Yang ◽  
Jiujun Cheng ◽  
Turlough M. Finan ◽  
Barry P. Rosen ◽  
Hiranmoy Bhattacharjee
Keyword(s):  
Sinorhizobium Meliloti ◽  
Physiological Function ◽  
Phosphate Transport ◽  
Transport Systems ◽  
Intact Cells ◽  
Arsenic Resistance ◽  
E Coli ◽  
Arsenic Detoxification ◽  
Selective Sensitivity

ABSTRACT We report a novel pathway for arsenic detoxification in the legume symbiont Sinorhizobium meliloti. Although a majority of ars operons consist of three genes, arsR (transcriptional regulator), arsB [As(OH)3/H+ antiporter], and arsC (arsenate reductase), the S. meliloti ars operon includes an aquaglyceroporin (aqpS) in place of arsB. The presence of AqpS in an arsenic resistance operon is interesting, since aquaglyceroporin channels have previously been shown to adventitiously facilitate uptake of arsenite into cells, rendering them sensitive to arsenite. To understand the role of aqpS in arsenic resistance, S. meliloti aqpS and arsC were disrupted individually. Disruption of aqpS resulted in increased tolerance to arsenite but not arsenate, while cells with an arsC disruption showed selective sensitivity to arsenate. The results of transport experiments in intact cells suggest that AqpS is the only protein of the S. meliloti ars operon that facilitates transport of arsenite. Coexpression of S. meliloti aqpS and arsC in a strain of E. coli lacking the ars operon complemented arsenate but not arsenite sensitivity. These results imply that, when S. meliloti is exposed to environmental arsenate, arsenate enters the cell through phosphate transport systems and is reduced to arsenite by ArsC. Internally generated arsenite flows out of the cell by downhill movement through AqpS. Thus, AqpS confers arsenate resistance together with ArsC-catalyzed reduction. This is the first report of an aquaglyceroporin with a physiological function in arsenic resistance.

Choosing a Markov blanket

2020 ◽  
Vol 43 ◽  
Author(s):  
Thomas Parr
Keyword(s):  
Markov Blanket ◽  
Target Article ◽  
The Relationship

Abstract This commentary focuses upon the relationship between two themes in the target article: the ways in which a Markov blanket may be defined and the role of precision and salience in mediating the interactions between what is internal and external to a system. These each rest upon the different perspectives we might take while “choosing” a Markov blanket.

Staring Down Death

Crisis ◽  
2016 ◽  
Vol 37 (3) ◽  
pp. 212-217 ◽  
Author(s):  
Thomas E. Joiner ◽  
Melanie A. Hom ◽  
Megan L. Rogers ◽  
Carol Chu ◽  
Ian H. Stanley ◽  
...  
Keyword(s):  
Suicide Risk ◽  
Clinical Utility ◽  
Blink Rate ◽  
Specific Task ◽  
Careful Planning ◽  
Eye Blink ◽  
Eye Blinks ◽  
Potential Clinical Utility ◽  
The Relationship

Abstract. Background: Lowered eye blink rate may be a clinically useful indicator of acute, imminent, and severe suicide risk. Diminished eye blink rates are often seen among individuals engaged in heightened concentration on a specific task that requires careful planning and attention. Indeed, overcoming one’s biological instinct for survival through suicide necessitates premeditation and concentration; thus, a diminished eye blink rate may signal imminent suicidality. Aims: This article aims to spur research and clinical inquiry into the role of eye blinks as an indicator of acute suicide risk. Method: Literature relevant to the potential connection between eye blink rate and suicidality was reviewed and synthesized. Results: Anecdotal, cognitive, neurological, and conceptual support for the relationship between decreased blink rate and suicide risk is outlined. Conclusion: Given that eye blinks are a highly observable behavior, the potential clinical utility of using eye blink rate as a marker of suicide risk is immense. Research is warranted to explore the association between eye blink rate and acute suicide risk.

Parenting Behaviors and Anxiety in Young Adults

2015 ◽  
Vol 36 (3) ◽  
pp. 170-176 ◽  
Author(s):  
Erin N. Stevens ◽  
Joseph R. Bardeen ◽  
Kyle W. Murdock
Keyword(s):  
Effortful Control ◽  
Parenting Behaviors ◽  
Protective Role ◽  
Anxiety Symptoms ◽  
Interactive Effects ◽  
Parental Overprotection ◽  
High Control ◽  
Development Of Anxiety ◽  
The Relationship

Parenting behaviors – specifically behaviors characterized by high control, intrusiveness, rejection, and overprotection – and effortful control have each been implicated in the development of anxiety pathology. However, little research has examined the protective role of effortful control in the relation between parenting and anxiety symptoms, specifically among adults. Thus, we sought to explore the unique and interactive effects of parenting and effortful control on anxiety among adults (N = 162). Results suggest that effortful control uniquely contributes to anxiety symptoms above and beyond that of any parenting behavior. Furthermore, effortful control acted as a moderator of the relationship between parental overprotection and anxiety, such that overprotection is associated with anxiety only in individuals with lower levels of effortful control. Implications for potential prevention and intervention efforts which specifically target effortful control are discussed. These findings underscore the importance of considering individual differences in self-regulatory abilities when examining associations between putative early-life risk factors, such as parenting, and anxiety symptoms.

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