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  • 1
    Electronic Resource
    Electronic Resource
    Cold stress response in Archaea (2000)
    Springer
    Extremophiles 4 (2000), S. 321-331 
    Details
    ISSN: 1433-4909
    Keywords: Key words Cold shock ; Low-temperature adaptation ; Psychrophile ; Adaptive mechanisms ; Antarctic Archaea ; Gene expression ; Protein structure ; Review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We live on a cold planet where more than 80% of the biosphere is permanently below 5°C, and yet comparatively little is known about the genetics and physiology of the microorganisms inhabiting these environments. Based on molecular probe and sequencing studies, it is clear that Archaea are numerically abundant in diverse low-temperature environments throughout the globe. In addition, non-low-temperature-adapted Archaea are commonly exposed to sudden decreases in temperature, as are other microorganisms, animals, and plants. Considering their ubiquity in nature, it is perhaps surprising to find that there is such a lack of knowledge regarding low-temperature adaptation mechanisms in Archaea, particularly in comparison to what is known about archaeal thermophiles and hyperthermophiles and responses to heat shock. This review covers what is presently known about adaptation to cold shock and growth at low temperature, with a particular focus on Antarctic Archaea. The review highlights the similarities and differences that exist between Archaea and Bacteria and eukaryotes, and addresses the potentially important role that protein synthesis plays in adaptation to the cold. By reviewing the present state of the field, a number of important areas for future research are identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007920070001
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  • 2
    Electronic Resource
    Electronic Resource
    Induction of cardiac angiotensin I-converting enzyme with dietary NaCl-loading in genetically hypertensive and normotensive rats (1995)
    Springer
    Journal of molecular medicine 73 (1995), S. 243-248 
    Details
    ISSN: 1432-1440
    Keywords: Angiotensin I-converting enzyme ; Gene expression ; Sodium chloride ; Heart ; Inbred rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have recently shown that the angiotensin I converting enzyme (ACE) gene is linked to NaCl-loaded blood pressure in the stroke-prone spontaneously hypertensive rat (SHRSP), and that high-NaCl loading selectively stimulates ACE in the aorta of SHRSP but not in normotensive Wistar-Kyoto (WKY) rats. We therefore investigated the relationship between cardiac ACE and the development of hypertension and left ventricular hypertrophy in response to normal- and high-NaCl diet in these rats. ACE mRNA and ACE activity were measured in left ventricular tissue after completion of hemodynamic characterization of the animals. While SHRSP rats increased blood pressure (P〈0.0001) and heart rate (P〈0.005) in response to high NaCl, blood pressure remained unchanged in WKY. Similarly, relative left ventricular weight increased only in SHRSP after high NaCl (P〈0.002). A significant two- to threefold increase of cardiac ACE mRNA and fourfold stimulation of ACE enzyme activity in response to high NaCl was found in both WKY and SHRSP rats (P〈0.005). The induction of ACE gene expression was significantly more pronounced in SHRSP compared to WKY (P〈0.02), whereas no significant strain differences in left ventricular ACE activity were found after either normal- or high-NaCl diet. Thus, arterial blood pressure and left ventricular weight remained unchanged in the WKY rats despite the activation of left ventricular ACE activity after high-NaCl exposure. These results demonstrate that left ventricular ACE activity is equally upregulated in response to high-NaCl in the normotensive and hypertensive strain, independently from the development of hypertension. We conclude that the pretranslational induction of left ventricular ACE with high-NaCl loading may be important both for the regulation of cardiac angiotensins and kinins and for local therapeutic ACE inhibition in the heart during high-salt status.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00189924
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  • 3
    Electronic Resource
    Electronic Resource
    Plasma-membrane H+-ATPase gene expression is regulated by NaCl in cells of the halophyte Atriplex nummularia L. (1993)
    Springer
    Planta 190 (1993), S. 433-438 
    Details
    ISSN: 1432-2048
    Keywords: Atriplex ; Gene expression ; NaCl regulation ; Halophyte ; Plasma-membrane H+-ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An Atriplex nummularia L. cDNA probe encoding the partial sequence of an isoform of the plasma-membrane H+ -ATPase was isolated, and used to characterize the NaCl regulation of mRNA accumulation in cultured cells of this halophyte. The peptide (447 amino acids) translated from the open reading frame has the highest sequence homology to the Nicotiana plumbaginifolia plasma-membrane H+-ATPase isoform pma4 (greater than 80% identity) and detected a transcript of approximately 3.7 kb on Northern blots of both total and poly(A)+ RNA. The mRNA levels were comparable in unadapted cells, adapted cells (cells adapted to and growing in 342 mM NaCl) and deadapted cells (cells previously adapted to 342 mM NaCl that are now growing without salt). Increased mRNA abundance was detected in deadapted cells within 24 h after exposure to NaCl but not in unadapted cells with similar salt treatments. The NaCl up-regulation of message abundance in deadapted cells was subject to developmental control. Analogous to those reported for glycophytes, the plasma-membrane H+-ATPase are encoded by a multigene family in the halophyte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224780
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  • 4
    Electronic Resource
    Electronic Resource
    Zero-field splitting versus interelectronic distance in triplet electron spin resonance spectra of localized dinitrenes (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 483-487 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Triplet zero-field splitting parameters were obtained in 2-methyltetrahydrofuran glass at 77 K for phenylene-1,4-dinitrene (1), biphenyl-4,4′-dinitrene (2), (E)-1,2-bis(4′-nitrenophenyl)ethene (3), 1,4-bis(4′-nitrenophenyl)buta-1,3-diene (4) and 1,8-bis(4′-nitrenophenyl)octa-1,3,5,7-tetraene (5). The results were (1) |D/hc| = 0·169 cm-1 |E/hc| = 0·004 cm-1, (2) |D/hc| = 0·189 cm-1, |E/hc| = 0·00 cm-1, (3) |D/hc| = 0·122 cm-1, |E/hc| = 0·00 cm-1, (4) |D/hc| = 0·0865 cm-1, |E/hc| = 0·00 cm-1 and (5) |D/hc| = 0·0442 cm-1, |E/hc| = 0·00 cm-1. All these biradicals are ground-state singlets. Based on the observed decrease in triplet signal intensities as temperature decreases. The substantial magnitudes of |D/hc| for 3-5, despite the large distance between localized nitrene electrons, is much more than can be explained by a simple dipolar interaction between localized electrons, and is attributed at least partly to spin polarization effects on the π-electron clouds of these systems.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060807
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  • 5
    Electronic Resource
    Electronic Resource
    Intramolecular exchange coupling of arylnitrenes by OXYGEN (1994)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 7 (1994), S. 495-502 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of m,n′-diazidodiphenyl ethers (m ≤ n, m = 3,4; n = 3,4) was photolyzed at 77 K in frozen, glassy 2-methyltetrahydrofuran matrices to generate the corresponding diphenyl ether m,n′-dinitrenes for study by electron spin resonance (ESR) spectroscopy. 3,4′-Diazidodiphenyl ether gave an ESR spectrum dominated by a mononitrene peak with ∣D/hc∣ = 0·972 cm-1, and also showed a weak dinitrene quintet spectrum with ∣D/hc∣ = 0·162 cm-1 having ESR spectral intensity vs temperature dependence (Curie law) consistent with either a high-spin ground state or a very small singlet-quintet gap. Di(3-azidophenyl) ether gave a strong mononitrene peak with ∣D/hc∣ = 0·996 cm-1 and a quintet dinitrene ESR spectrum (∣D/hc∣ = 0·162 cm-1) which exhibited non-linear Curie law intensity behavior consistent with the quintet being a thermally populated excited state 40 cal mol-1 above a singlet ground state. Di(4-azidophenyl) ether gave a strong mononitrene peak with ∣D/hc∣ = 0·961 cm-1, but no observable spectrum related to a high-spin open-shell dinitrene. The results are consistent with oxygen being a weak exchange coupling linker in pi-conjugated open-shell molecules. The observed ground-state spin multiplicities are in accord with qualitative superexchange and connectivity models, despite any perturbations due to resonance effects between the oxygen linker and p-nitrene sites.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610070905
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  • 6
    Electronic Resource
    Electronic Resource
    Enthalpies of micelle formation by hexadecyltrimethylammonium bromide in aqueous solution containing pentanol (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 108-112 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Titration calorimetric data show a dramatic change from endo- to exothermic deaggregation when pentanol-hexadecyltrimethylammonium bromide (CTAB) mixed solutions are injected into an aqueous solution containing pentanol. The results are interpreted in terms of a change in the structures of the aggregates in solution from simple CTAB micelles to mixed amphiphilic microheterogeneities when pentanol is added.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080210
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  • 7
    Electronic Resource
    Electronic Resource
    Short Communications. Biphenyl-3,4′-Dinitrene (1991)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 4 (1991), S. 459-462 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photolysis of biphenyl-3,4′ -diazide in a rigid glassy matrix at 77 K yields quintet state biphenyl-3,4′ -dinitrene with zero-field splitting parameters of |D/hc- = 0.153 cm-1 and |E/hc| = 0.019 cm-1 determined by electron spin resonance spectroscopic studies. Curie plot studies are consistent with assigning the quintet to be the ground state in this species. This finding confirms qualitative connectivity-based predictions for this general connectivity type of openshell system, and is in qualitative agreement with spectral INDO-CI computational predictions for both planar and twisted geometries of the dinitrene.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610040708
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