Comparative Biochemistry of the Alkali Metals

Steinbach, H. Burr

doi:10.1016/b978-0-12-395545-6.50022-5

Cited by 8 publications

(5 citation statements)

References 120 publications

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“…Some unknown percentage of each element was most probably complexed with tissue proteins or other organics which were spun-down during centrifugation of the distilled water diluted homogenates. However, these three elements occur mostly as free, noncomplexed ions in extracellular and intracellular body fluids (Steinbach, 1962;Oser, 1965). Losses due to centrifugation were considered to be inconsequential to the scope of this study since complexed forms of chloride, sodium and potassium would be osmotically inactive anyway.…”

Section: Tissue Fluid Osmolalitymentioning

confidence: 99%

OSMOTIC ADJUSTMENT IN AN ESTUARINE POPULATION OFUROSALPINX CINEREA(SAY, 1822) (MURICIDAE, GASTROPODA)

Turgeon

1976

The Biological Bulletin

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Individuals from a subtidal, estuarine population of the common oyster drill, Urosalpinx cinerea (Say, 1822), were brought into the laboratory and tested for osmotic adjustment to changing salinity. Tissue variables monitored at seven experimental salinities ranging from 10 to 40% were tissue fluid osmolality, chloride, sodium, potassium, free amino acids (FAA), ninhydrin-positive substances (NPS) and water content. The results of this study demonstrate that the test animals did not exhibit anisosmotic regulation at any of the experimental salinities. However, the data do suggest a high degree of hyper-ionic regulation of potassium at all experimental salinities and a hyporegulation of sodium between the 25 and 40% salinities. Taurine, aspartic acid, alanine and glycine were the four FAA present in relatively consistent high amounts. These four amino acids comprised from 59.6 to 75.7% of the total FAA pools. It is postulated that the population does not maintain its euryhaline survival status through an osmoregulatory mechanism. Rather, the population has probably adapted physiologically to withstand dilution of its body fluids during spring conditions of low salinities.

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Section: Tissue Fluid Osmolalitymentioning

confidence: 99%

OSMOTIC ADJUSTMENT IN AN ESTUARINE POPULATION OFUROSALPINX CINEREA(SAY, 1822) (MURICIDAE, GASTROPODA)

Turgeon

1976

The Biological Bulletin

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“…Potassium (K+) is the major cytoplasmic cation of growing bacterial cells (11,12,27), in which it plays a role in the activation of cytoplasmic enzymes (28), in the maintenance of turgor pressure (10,23), and possibly in the regulation of cytoplasmic pH (4,7,22). The size of the K+ pool is regulated by the osmotic pressure of the growth medium (9).…”

mentioning

confidence: 99%

Evidence for multiple K+ export systems in Escherichia coli

Bakker¹,

Booth²,

Dinnbier³

et al. 1987

J Bacteriol

110

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The role of the K+ transport systems encoded by the kejB (formerly trkB) and kefC (formerly trkC) genes of Escherichia coli in K+ efflux has been investigated. The rate of efflux produced by N-ethylmaleimide (NEM), increased turgor pressure, alkalinization of the cytoplasm, or 2,4-dinitrophenol in a mutant with null mutations in both kef genes was compared with the rate of efflux in a wild-type strain for kef. The results show that these two genes encode the major paths for NEM-stimulated efflux. However, neither efflux system appears to be a significant path of K+ efflux produced by high turgor pressure, by alkalinization of the cytoplasm, or by addition of high concentrations of 2,4-dinitrophenol. Therefore, this species must have at least one other system, besides those encoded by keJB and kefC, capable of mediating a high rate of K+ efflux. The high, spontaneous rate of K+ efflux characteristic of the keJCl21 mutation increases further when the strain is treated with NEM. Therefore, the mutational defect that leads to spontaneous efflux in this strain does not abolish the site(s) responsible for the action of NEM.Potassium (K+) is the major cytoplasmic cation of growing bacterial cells (11,12,27), in which it plays a role in the activation of cytoplasmic enzymes (28), in the maintenance of turgor pressure (10,23), and possibly in the regulation of cytoplasmic pH (4,7,22). The size of the K+ pool is regulated by the osmotic pressure of the growth medium (9). In Escherichia coli, this regulation is believed to act at the level of control of the synthesis (14) and activity (11,16,24) of the uptake systems and the activity of efflux (19). Studies of efflux have been hampered by the limited knowledge of the genes which affect this process. Two genetic loci, trkB and trkC, have been identified by mutations that cause a requirement for high levels of K+ in the growth medium because of enhanced rates of K+ leakage (25). Recently, it was shown that these mutations affect two separate K+ efflux systems, which thereby become overactive (5). These lesions can be suppressed by intragenic null mutations or by the insertion of transposons into the mutated gene. The only other mutant of E. coli with altered K+ efflux is strain KHA, which was reported to have lost K+/H+ antiport activity (22). However, a detailed genetic analysis of this strain has not been presented.K+ efflux can also be elicited by a variety of cell treatments including addition of N-ethylmaleimide (NEM), alkalinization of the cytoplasm, or increased turgor pressure (18)(19)(20). In each case, it is believed that efflux occurs via K+/H+ antiporters (3, 20). The NEM effect on the K+ pool is reversible even in the absence of protein synthesis (18), and this has led to the proposal that NEM exerts its action by titration of the glutathione pool rather than by covalent modification of a protein target. Thus, it has been proposed that control of K+ retention is mediated by glutathione (17).The experiments described here were initiated to ascertain the relative ...

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“…[Considered nonessential for organisms] Steinbach (1962) stated that rubidium appears not to be an essential component of living matter, but rather a toxic agent that may partly substitute for potassium. He reported rubidium in non-woody plants to range from 11.3 to 36.7 ppm (dry weight basis).…”

Section: Rubidiummentioning

confidence: 99%

Element concentrations toxic to plants, animals, and man

Gough¹,

Shacklette²,

Case³

1979

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Much has been written on the toxicities of some elements such as lead, mercury, and selenium, and our chief task with these elements was that of selecting the most useful reports to include. For some other elements, reports of toxicities are few and often in obscure publications. The elements selected for this discussion are those that may be environmentally important and especially those for which we have quantitative data. Some of the information in this outline is from unpublished data in our files; most statements, however, are identified by reference citations. The elements are presented alphabetically by their common English names. We have divided the notes on each element into three parts plants, animals, and man and classified associated toxicities under natural and man-induced conditions, where appropriate. References to the toxicities of a few elements of possible environmental concern are inadequate for an evaluation to be made of their hazard. These elements are grouped near the end of this report, and a general discussion is given of the available information on each element. Concentrations of elements generally are presented as parts per million (ppm), although other methods of expressing concentrations may be quoted. In some instances units such as mg/kg of body weight, jumoles/L, ju,g/m3, parts per billion (ppb), or percent provide a clearer concept for a given example, and converting them to ppm was considered to be unnecessary. A part per million is 10~4 percent and a part per billion is 10~7 percent. It will be noted in this report that many of the elements are essential for plants or animals, yet are toxic under certain conditions (Wallace, Romney, Alexander, and Kinnear, 1977). The toxicity of an element depends, first of all, on its chemical form. For example, chlorine in the elemental form (a gas) is highly toxic, whereas chlorine compounds may be relatively harmless, as is sodium chloride (common salt). Conversely, elemental arsenic is not toxic, although some arsenical compounds are highly toxic. Many reports do not specify the chemical form of an element when discussing its toxicity. It can be assumed for most of these reports that, under the specified natural or experimental conditions, the element existed in an undetermined compound and that only the total concentration of the element was known. For most reports in which the basis for expressing concentrations of an element in plant or animal tissues is not specified, a dry-weight basis can be assumed. The toxicity of a substance is also determined by the dosage that is, the amount (in relation to body weight or to the growth medium) and the frequency and duration of administering the substance to the organism. The duration of specified dosages of toxic elements was not given by some investigators, including Bowen in table 7.4 of his 1966

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Comparative Biochemistry of the Alkali Metals

Cited by 8 publications

References 120 publications

OSMOTIC ADJUSTMENT IN AN ESTUARINE POPULATION OFUROSALPINX CINEREA(SAY, 1822) (MURICIDAE, GASTROPODA)

OSMOTIC ADJUSTMENT IN AN ESTUARINE POPULATION OFUROSALPINX CINEREA(SAY, 1822) (MURICIDAE, GASTROPODA)

Evidence for multiple K+ export systems in Escherichia coli

Element concentrations toxic to plants, animals, and man

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