Double quantum sodium NMR studies of the halotolerant Ba1 bacterium

Sakhnini, As'ad; Gilboa, Haggai

doi:10.1016/0301-4622(93)87003-f

Cited by 8 publications

(3 citation statements)

References 15 publications

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“…Another conclusion might be that the intracellular environment change only slightly when the medium changes drastically, as it may be deduced from the cesium chemical shifts. A similar conclusion was obtained from the sodium relaxation times in Ba 1 cells measured with the help of double quantum filtering, 21 where the sodium relaxation times, in the cytosol, T 2f and T 2s were similar at 0.4 and 0.8 M salt concentrations of the media. The suggestion was that the microenvironment for the sodium ions in the cytosol was similar for the different media salt concentrations.…”

Section: Salt Concentration (M)supporting

confidence: 82%

Nuclear magnetic resonance studies of cesium-133 in the halophilic halotolerant bacterium Ba1. Chemical shift and transport studies

Sakhnini

Gilboa

1998

NMR Biomed.

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Ba1 bacteria (Holomonas israelensis ) were grown on different salt concentrations 0.2–4 M. When the cells were transferred to a medium containing 25 mM CsCl without potassium there was an uptake of cesium by the cells. The intracellular cesium signal was shifted from the cesium signal in the medium without the use of a shift reagent. The shift was depended on the salt concentration in the growth medium. The intracellular cesium shift showed a much smaller dependence on the concentration of salts in the medium than the extracellular cesium; the same results were detected for cells grown on a medium containing 25 mM CsCl. The cesium transport through the cell membrane was mostly by active transport. The cesium concentration in the cell was higher than that of the medium, ∼100 mM intracellular concentration compared to 25 mM in the medium. The first order constants for influx or efflux of cesium were from 2 × 10−4 and up to 24 × 10−4 /min for the different medium concentrations. © 1998 John Wiley & Sons, Ltd.

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Section: Salt Concentration (M)supporting

confidence: 82%

Nuclear magnetic resonance studies of cesium-133 in the halophilic halotolerant bacterium Ba1. Chemical shift and transport studies

Sakhnini

Gilboa

1998

NMR Biomed.

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“…Since the shift reagent [dysprosium bis(tripolyphosphate)] used to discriminate between extracellular and cell-associated Na ϩ was not effective at the highest NaCl concentrations, the approach could be applied up to about 2 M salt only. In the concentration range tested, the "NMR-visible" intracellular Na ϩ concentration never exceeded 15 to 20% of the medium concentration (97,299). It should be noted that the use of shift reagents may lead to faulty results as they form complexes and therefore disturb the equilibrium across the membrane.…”

Section: Internal Ion Concentrationsmentioning

confidence: 94%

Biology of Moderately Halophilic Aerobic Bacteria

Ventosa

Nieto

Oren

1998

Microbiol Mol Biol Rev

1,165

524

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SUMMARY The moderately halophilic heterotrophic aerobic bacteria form a diverse group of microorganisms. The property of halophilism is widespread within the bacterial domain. Bacterial halophiles are abundant in environments such as salt lakes, saline soils, and salted food products. Most species keep their intracellular ionic concentrations at low levels while synthesizing or accumulating organic solutes to provide osmotic equilibrium of the cytoplasm with the surrounding medium. Complex mechanisms of adjustment of the intracellular environments and the properties of the cytoplasmic membrane enable rapid adaptation to changes in the salt concentration of the environment. Approaches to the study of genetic processes have recently been developed for several moderate halophiles, opening the way toward an understanding of haloadaptation at the molecular level. The new information obtained is also expected to contribute to the development of novel biotechnological uses for these organisms.

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“…Two main techniques can be used to distinguish the resonances of intracellular and extracellular sodium. The first is based on the difference in relaxation properties of Na in ϩ and Na ex ϩ , which was exploited in multiple quanta-filtered NMR experiments (1,2). Alternatively, a second approach, more generally used, consists in using shift reagents which are anionic complexes of lanthanides (Dy 3ϩ , Tm 3ϩ , Tb 3ϩ ) whose paramagnetic properties, when exchanging with external sodium, induce a chemical shift in external Na ϩ resonance.…”

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confidence: 99%