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  • Haemocyanin  (3)
  • 3H  (1)
  • AC-ECD  (1)
  • Springer  (5)
  • Munksgaard International Publishers
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  • Springer  (5)
  • Munksgaard International Publishers
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  • 1
    ISSN: 1432-136X
    Keywords: Crustacea ; Amphipoda ; Haemocyanin ; Temperature sensitivity ; l-Lactate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of pH, temperature, and l-lactate on the O2 bindign properties of haemocyanin (Hc) from three talitroidean species i.e., the aquatic Apohyale pugettensis, the semi-terrestrial Megalorchestia californiana, and the semi-/euterrestrial Traskorchestia traskiana was studied. The Hc of A. pugettensis was characterized by a higher O2 affinity (and more pronounced Bohr shift) than the Hc of either M. californiana or T. traskiana. Apohyale was the only species that possessed He that was sensitive to temperature change. Resuspending Hc from each of the three species in a stock Ringer's solution (based on the ionic composition of the haemolymph of T. traskiana) showed that the persistence of the difference in Bohr shift between Apohyale and the other two species was due to differences in the haemocyanins themselves and not attributable to their respective ionic environments. An inverse relationship was found between the cooperativity (n 50) and pH of Hc from T. traskiana and A. pugettensis but not for M. californiana. In each case adding l-lactate increased Hc O2 affinity, but this was most pronounced for A. pugettensis.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-136X
    Keywords: Crustacea ; Amphipoda ; Haemocyanin ; O2 transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Haemolymph PO2 and pH of two amphipod species, Apohyale pugettensis (aquatic) and Megalorchestia californiana (semi-terrestrial) in vivo were examined during immersion and emersion at 15 and 25°C, and also after activity in air at 15°C. For M. californiana arterial O2 tensions were higher in air than in water. This situation was reversed in A. pugettensis, although all O2 tensions measured for both species were comparatively high. No arterial-venous PO2 difference was apparent in the haemolymph of quiescent M. californiana. Haemocyanin (Hc) was 100% saturated in vivo only in the following; A. pugettensis in water (15 and 25°C) and air (15°C), and M. californiana in air (15°C). The Hc of both species becomes important in O2 transport during activity; under such circumstances the haemolymph of M. californiana delivered more O2 to the tissues than did that of A. pugettensis, despite the greater O2 content of the latter. The animals studied here may exhibit a stage (size class?) where cutaneous gas exchange is sufficient for resting aerobic metabolism while specialized respiratory carriers (and respiratory structures) are important in meeting the increased aerobic demands of activity or environmental stress.
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  • 3
    ISSN: 1432-136X
    Keywords: Amphipoda ; Crustacea ; Haemocyanin ; Freezing ; Inorganic effectors ; Urate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of variations in [K], [Ca], [Mg], [NaCl], and [urate] on the in vitro O2 binding properties of haemocyanin (Hc) from three talitroidean species, viz. the aquatic Apohyale pugettensis, the semi-terrestrial Megalorchestia californiana, and the semi-/euterrestrial Traskorchestia traskiana were studied. Freezing altered the cooperativity of Hc from A. pugettensis and M. californiana but not T. traskiana. Variations in [NaCl], [K], and [Mg] had no effect on cither O2 affinity or cooperativity of the Hc except for A. pugettensis Hc where an increase in [Mg] resulted in an increase in both O2 affinity and cooperativity. Increasing [Ca] or [urate] increased O2 affinity of both A. pugettensis and M. californiana but not T. traskiana Hc. These effects were most marked in A. pugettensis. The results suggest a negative correlation between sensitivity to Hc effectors and the degree of terrestrial adaptation of a particular amphipod species.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 96 (1988), S. 11-26 
    ISSN: 1436-5073
    Keywords: electron capture detector (ECD) ; electron oscillation ; AC-ECD ; argon-methane ; non-homogeneous ECD kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oscillation of electrons—as driven by AC polarization—can be used to extract a high-sensitivity signal from a conventional electron capture detector. For example, hexachloroethane was detected at a hypercoulometric ratio of 2.0 F/mol, down to ca. 60 fg/s (S/N=3) and with a linear range in excess of two orders of magnitude. The change in carrier gas from nitrogen to argon-methane produced the expected order-of-magnitude increase in optimum oscillation frequency. Anab initio simulation of potentials and ion populations in a heterogeneous electron capture system under a high-frequency AC regime provided further insight into the detector's mechanism: Hypercoulometric response is mainly caused by increased cation-electron recombination in the plasma region, owing to a decreased field gradient and an increased cation concentration.
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  • 5
    ISSN: 1436-5073
    Keywords: ionization topography ; 3H ; 63Ni ; electron capture detector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The ion-pair generation rate (ionization topography) in plasmas from63Ni and particularly Ti3H4 foils, as used in electron capture detectors, was measured at room temperature using large, parallel plates of low backscattering ability in nitrogen gas of varying density. For one atmosphere pressure, the fall-off of ion pair formation as calculated from the exponential region equalsN 0·e −0.19d for63Ni andN 0·e −1.4d for3H (whereN 0 is the initial ionization rate immediately adjacent to the foil andd is the distance from the foil in mm). The experimentally measured half ranges (distances from the foil within which 50% of all possible ion pairs are created) are 2.7 mm for63Ni and 0.27 mm for3H. The half ranges calculated from the exponential region where there is less interference from electron backscattering, are 3.7 and 0.5 mm, respectively. The latter values are considered closer to the “true”, unimpeded ionization topography near planar63Ni and3H foils.
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