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  • 1
    Electronic Resource
    Electronic Resource
    Transient breakdown in the selective permeability of the plasma membrane ofChlorella emersonii in response to hyperosmotic shock: Implications for cell water relations and osmotic adjustment (1984)
    Springer
    The journal of membrane biology 82 (1984), S. 83-88 
    Details
    ISSN: 1432-1424
    Keywords: Chlorella emersonii ; unicellular alga ; osmotic responses ; cell volume ; membrane permeability ; hyperosmotic shock ; osmometric behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary In osmotic experiments involving cells of the euryhaline unicellular green algaChlorella emersonii exposed to hyperosmotic stress by immersion in a range of low molecular weight organic and inorganic solutes, a temporary breakdown in the selective permeability of the plasma membrane was observed during the initial phase of transfer to media of high osmotic strength (up to 2000 mosmol kg−1). Thus, although the cells appeared to obey the Boyle-van't Hoff relationship in all cases, showing approximately linear changes in volume (at high salinity) as a function of the reciprocal of the external osmotic pressure, the extent of change was least for the triitols, propylene glycol and glycerol, intermediate for glucose, sorbitol, NaCl and KCl, with greatest changes in media containing the disaccharides sucrose and maltose. In NaCl-treated cells, uptake of external solute and loss of internal ions was observed in response to hyperosmotic treatment while sucrose-treated cells showed no significant uptake of external solute, although loss of intracellular K+ was observed. These observations suggest that the widely used technique of estimating cellular turgor, and osmotic/nonosmotic volume by means of the changes in volume that occur upon transfer to media containing increasing amounts of either a low molecular weight organic solute or an inorganic salt may be subject to error. The assumption that all algal cells behave as “ideal osmometers,” with outer membranes that are permeable to water but not to solutes, during the course of such experiments is therefore incorrect, and the data need to be adjusted to take account of hyperosmotically induced external solute penetration and/or loss of intracellular osmotica before meaningful estimates of cell turgor and osmotic volume can be obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870734
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  • 2
    Electronic Resource
    Electronic Resource
    Natural abundance 13C-nuclear magnetic resonance spectroscopic analysis of acyclic polyol and trehalose accumulation by several yeast species in response to salt stress (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 82 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: Analysis of seventeen yeast strains by 13C-NMR spectroscopy has confirmed the significance of glycerol as the sole osmoregulatory solute under salt-stressed conditions, and has shown arabitol to be present in most of the osmotolerant species. Ribitol was detected in some species, including Debaryomyces hansenii, although ribitol accumulation did not correlate with the osmotic pressure of the medium. Relative amounts of arabitol and ribitol decreased in relation to glycerol when the external osmotic pressure was increased. Trehalose was present during exponential growth of some species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04859.x
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  • 3
    Electronic Resource
    Electronic Resource
    The osmotic responses of Saccharomyces cerevisiae in K+-depleted medium (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 78 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Saccharomyces cerevisiae showed reduced growth in a K+-depleted medium but was still capable of synthesizing and accumulating glycerol in the presence of 2.28% (w/v) NaCl; glycerol levels were similar in both K+-replete and K+-depleted media. The activity of glycerol-3-phosphate dehydrogenase, a key enzyme of glycerol synthesis, was inhibited to a similar extent by exogenous K+ and Na+ although such effects may be modified in vivo due to ionic compartmentation within the vacuole. These results indicate that exogenous K+ does not play a significant role in the initiation of glycerol synthesis in osmotically-stressed yeast.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04423.x
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  • 4
    Electronic Resource
    Electronic Resource
    Low-molecular mass carbohydrate accumulation in cyanobacteria from a marine microbial mat in response to salt (1987)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 45 (1987), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Forty seven strains of cyanobacteria, all isolated from microbial mats of intertidal sediments of the island of Mellum (North Sea), were analyzed for the presence of organic osmotica. The cyanobacteria examined belonged to taxonomically different groups and were classified according to their salt optimum and salt tolerance as either freshwater, brackish or marine. Except betaine, all organic osmotica known to occur in cyanobacteria, were found. The results showed no clear correlation between the chemical nature of the organic solute and the salt optimum or salt tolerance of the cyanobacteria examined, indicating that these solutes are not specific to this marine habitat. All strains belonging to the Nostoc/Anabea-group accumulated sucrose as the sole organic osmoticum. The marine, heterocystous Calothrix sp. accumulated trehalose. All strains of the LPP-group (Lyngbya, Plectonema, Phormidium) accumulated glucosylglycerol as sole or primary organic solute. Some LPP-strains accumulated a disaccharide as a secundary solute, e.g. sucrose or trehalose. Gloeocapsa, Synechocystis and Spirulina accumulated glucosylglycerol. Two marine Oscillatoria accumulated trehalose, whereas a freshwater Oscillatoria with a broad salinity tolerance, accumulated sucrose.Analysis of field samples of the microbial mats demonstrated the presence of glycerol, glucosylglycerol, sucrose and trehalose. The relative abundance of the different compounds was related to the species composition as could be predicted from laboratory observations. These data suggest that these carbohydrates have a function in maintaining osmotic balance in the organisms within the microbial mat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1987.tb02381.x
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  • 5
    Electronic Resource
    Electronic Resource
    Multiphasic osmotic adjustment in a euryhaline cyanobacterium (1985)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 28 (1985), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Transfer of Synechocystis PCC6714 from a freshwater medium to a saline medium caused the cells to shrink; rapid entry of NaCl resulted in a partial recovery of cellular volume within 2 min. Active extrusion of internal Na+ in exchange for extracellular K+ then occurred (within 20 min). Finally, the low-Mr carbohydrates sucrose and glucosylglycerol were accumulated and internal KC1 levels declined. In long-term growth experiments, the relative importance of sucrose as a component of the low-Mr organic solute fraction decreased and glucosylglycerol became the single most important intracellular solute. These observations demonstrate that several inorganic and organic solutes are involved in osmotic adjustment in this cyanobacterium, with sequential changes in the relative importance of each solute following transfer to a saline medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1985.tb00796.x
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  • 6
    Electronic Resource
    Electronic Resource
    The ionic relations of Porphyra purpurea(Roth) C.Ag. (Rhodophyta, Bangiales) (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 3 (1980), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Radioisotope equilibration techniques have been used to determine the intracellular concentration of K+, Na+ and Cl−, together with the unidirectional ion fluxes across the plasmalemma of Porphyra purpurea. Influx and efflux of 42K+, 24Na+ and 36C1− are biphasic, the rapid, initial uptake and loss of tracer from individual thalli being attributable to desorption from extracellular regions. Cellular fluxes are slower and monophasic, cells discriminating in favour of K+ and Cl− and against Na+. A comparison between the equilibrium potential of individual ion species and the measured membrane potential demonstrates that there is an active component of K+ and Cl− influx and Na+ efflux. ‘Active’ uptake and ‘passive’ loss of K+ and Cl− are reduced when plants are kept in darkness, suggesting that a fraction of the transport of K+ and Cl− may be due to ‘exchange diffusion’ (K+/K+ and Cl−/Cl−antiport).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11586851
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  • 7
    Electronic Resource
    Electronic Resource
    Use and abuse of osmo-terminology (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 7 (1984), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The terminology currently employed in studies concerned with the osmotic responses of plant cells is reviewed with specific reference to (1) the suitability of expressions in general use and (2) the application of such terms to experimental studies. The widely used term osmoregulation is shown to be an inappropriate and misleading expression when used to describe the adjustments in cellular solute concentration which frequently accompany changes in external salt concentration. Such usage of osmoregulation should be discouraged; more suitable expressions (e.g. osmoacclimation, osmotic adjustment, turgor/volume regulation or turgor maintenance, osmoadaptation) should be employed, depending upon the context.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11614591
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  • 8
    Electronic Resource
    Electronic Resource
    Membrane potential measurements of marine macroalgae: Porphyra purpurea and Ulva lactuca (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 4 (1981), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Accumulation of the lipophilic cation tri-phenylmethylphosphonium (TPMP+) has been used to estimate the plasmalemma potential (Φm) of Porphyra purpurea (Rhodophyta, Bangiales) and Ulva lactuca (Chlorophyta, Ulvales). Values of Φm obtained using the Nernst equation were −61 mV and −54 mV respectively; these values compare well with those obtained using glass microelectrodes. A trend of hyperpolarization of Φm in P. purpurea was observed with decreasing external salinity. This hyperpolarization was shown to be primarily due to changes in external K+ concentration. Varying external Na+ concentration was found to have little effect on Φm. The present data suggest that the membrane potential of P. purpurea is not wholly due to a K+ diffusion potential, but may have an electrogenic component.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11611040
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  • 9
    Electronic Resource
    Electronic Resource
    Incorporation of 14C in the cyanobacterium Synechococcus PCC 6301 following salt stress (1990)
    Springer
    Planta 181 (1990), S. 393-398 
    Details
    ISSN: 1432-2048
    Keywords: Cyanobacteria ; Osmoregulation ; Photosynthesis and salt stress ; Salt stress ; Sucrose synthesis and salt stress ; Synechococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Synechococcus PCC 6301 synthesized sucrose as a compatible solute following hyperosmotic shock induced by NaCl. Initial rates of photosynthetic 14C incorporation were reduced following salt shock. Photosynthetic rates were comparable in cells enriched for glycogen (by growth in NO 3 - -deficient medium) and cells grown in NO 3 - -sufficient medium in the absence of osmotic shock. Incorporation of 14C was predominantly into the NaOH fraction and the residual acidic fraction in cells grown in NO 3 - -sufficient medium, whereas incorporation was predominantly into the residual acidic fraction in cells grown in NO 3 - -deficient medium. Following salt stress, 14C incorporation was initially into the ethanol-soluble fraction and the majority of tracer was recovered in sucrose. Carbon-14 was detected in sucrose in cells which had been enriched for [14C]glycogen prior to salt stress, inferring that glycogen can act as a carbon source for sucrose synthesis following salt stress. Changes in the specific activity of sucrose are consistent with an initial synthesis of sucrose from glycogen followed by synthesis of sucrose using newly fixed carbon, in response to salt stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195893
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  • 10
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    Unknown
    Altritol in the brown alga Himanthalia elongata (1984)
    Elsevier
    Details
    Publication Date: 1984-01-01
    Print ISSN: 0031-9422
    Electronic ISSN: 1873-3700
    Topics: Biology , Chemistry and Pharmacology
    Published by Elsevier
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