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  • 1
    Electronic Resource
    Electronic Resource
    Invariant kinetic approach to the description of a rock fracture process and induced seismic events (1996)
    Springer
    Pure and applied geophysics 147 (1996), S. 367-375 
    Details
    ISSN: 1420-9136
    Keywords: Induced seismicity ; kinetics ; rock fracture ; rockburst ; earthquake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Powerful seismic events, such as earthquakes and rockbursts, are caused by the accumulation of energy in rocks and loss of rock mass stability. Usually methods of their forecasting are based on the registration of anomalous behavior of geophysical fields. However an efficiency of this approach is low. The present paper proposes a kinetic approach to the description of rock fracture process, which can be used for the forecasting of seismic events and an investigation of structure and energy distributions in rock. 3-D and 1-D kinetic equations describing a process of cluster formation in rock were obtained. The equations are invariant to deformation conditions and to the scale level of events. They showed a good agreement with the results of field observations and laboratory experiments. It was also shown that these equations well describe the processes of earthquake, rockburst and rock sample failure preparation. Catalogues of rockbursts in mines were analyzed with the use of the kinetic equations to find out evidence of induced seismic events. The proposed approach makes it possible to reveal trends in rock behavior and thus predict the rock failure at different scale levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877489
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of pyrophosphate and orotidine monophosphate on cytosine deaminase regulatory properties (1985)
    Springer
    Cellular and molecular life sciences 41 (1985), S. 1563-1564 
    Details
    ISSN: 1420-9071
    Keywords: Cytosine deaminase ; kinetics ; pyrophosphate ; orotidine monophosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The maximal velocity of the reaction (Vmax) and the half-saturation constant (K0.5) values of theS. typhimurium cytosine deaminase were altered in the presence of its effectors, pyrophosphate and orotidine monophosphate. From the kinetics of orotidine monophosphate inhibition of cytosine deaminase, it was characterized as a mixed-type noncompetitive inhibitor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01964808
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of host plant and larval diet on ovarian productivity inAcrolepiopsis assectella Z. (Lepidoptera: Acrolepiidae) (1986)
    Springer
    Cellular and molecular life sciences 42 (1986), S. 448-450 
    Details
    ISSN: 1420-9071
    Keywords: Lepidoptera ; Acrolepiopsis assectella ; host plant ; larval diet ; ovarian production ; stimulation ; insemination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Females ofAcrolepiopsis assectella, reared on a semi-synthetic diet and laying on artificial substrates, do not respond to external stimuli by increasing ovarian production. When returned to the natural host (Allium porrum) for only one generation, ovarian production again rises and reaches the same level as in wild females, but its variability is strongly reduced. We conclude that selection under artificial conditions eliminates individuals which strictly depend on host plants for stimulation of larval nutrition and of reproduction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02118653
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  • 4
    Electronic Resource
    Electronic Resource
    Photoperiodic diapause induction suppressed at low temperatures in a long-day insect (1988)
    Springer
    Cellular and molecular life sciences 44 (1988), S. 788-789 
    Details
    ISSN: 1420-9071
    Keywords: Yponomeuta vigintipunctatus ; Lepidoptera ; Yponomeutidae ; diapause ; photoperiodic induction curves ; low temperature influence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The long-day insectYponomeuta vigintipunctatus was subjected to various combinations of temperature and photoperiod. The photoperiodic induction curve at 10°C resembled the one at 20°C, but with a shift of the critical photoperiod towards the shorter day-length. Such unusual averting of diapause at lower temperatures in combination with intermediate long-day photoperiods has still been described in only few insect species of the temperate zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01959167
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  • 5
    Electronic Resource
    Electronic Resource
    Are host plants important in pheromone-mediated mating systems of lepidoptera? (1989)
    Springer
    Cellular and molecular life sciences 45 (1989), S. 236-240 
    Details
    ISSN: 1420-9071
    Keywords: Lepidoptera ; semiochemicals ; sex pheromones ; host plants ; secondary plant compounds ; calling behaviour ; mate choice ; Homoesoma electellum ; Pseudaletia unipuncta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The role of host plants in the synthesis and release of lepidopteran sex pheromones is examined. Females synthesise pheromones de novo and pheromone quality is not markedly influenced by larval food sources. However, host plants may have a significant effect on different physiological and behavioural parameters associated with pheromone production. Males in some species of Nymphalidae and Arctiidae use secondary plant compounds, such as pyrrolizidine alkaloids, as a pheromone precursor. In such cases these plant compounds serve an additional role, such as protection against predation, and may reflect potential male reproductive investment. In the one instance where the effect of larval host plants on the de novo synthesis of a male sex pheromone was examined, larval nutrition did not alter either the quality or quantity of the hairpencil contents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01951809
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  • 6
    Electronic Resource
    Electronic Resource
    A comparison of pyridoxal 5′-phosphate dependent decarboxylase and transaminase enzymes at a molecular level (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 1104-1118 
    Details
    ISSN: 1420-9071
    Keywords: Transaminase ; decarboxylase ; serine hydroxymethyltransferase ; pyridoxal 5′-phosphate ; enzyme mechanism ; stereochemistry ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Pyridoxal 5′-phosphate is a coenzyme for a number of enzymes which catalyse reactions at Cα of amino acid substrates including transaminases, decarboxylases and serine hydroxymethyltransferase. Using the X-ray coordinates for a transaminase, aspartate aminotransferase, and the results of stereochemical and mechanistic studies for decarboxylases and serine hydroxymethyltransferase, an active-site structure for the decarboxylase group is constructed. The structure of the active-site is further refined through active-site pyridoxyllysine peptide sequence comparison and a 3-D catalytic mechanism for the L-α-amino acid decarboxylases is proposed. The chemistry of serine hydroxymethyltransferase is re-examined in the light of the proposed decarboxylase mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01918374
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  • 7
    Electronic Resource
    Electronic Resource
    Über den Einfluß der Kulturdauer im larvalen Wirt auf die Entwicklungsleistungen implantierter männlicher Genitalimaginalscheiben vonEphestia, kuehniella Z. (1979)
    Springer
    Development genes and evolution 186 (1979), S. 309-331 
    Details
    ISSN: 1432-041X
    Keywords: Lepidoptera ; Male genital disk ; Implantation ; Regeneration ; Control of metamorphosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Complete and bisected male genital disks (HO) from full-grown (T9) larvae were transplanted either into larvae and pharate pupae of different age (T4, T7, T9 larvae, A1–A5 pharate pupae) or repeatedly transferred into full-grown larvae before being implanted into a final larval host. After metamorphosis of the hosts, most of the complete transplants and regenerated HO halves showed normal morphological features, but the implanted genitals from old pharate pupae (A4 and A5) were abnormally differentiated. Frequency of Regeneration. After transplanting both halves of the bisected HO into T9 hosts, three groups of results were observed: (1) each of the two halves regenerated into a complete genital organ; (2) only one half regenerated; (3) neither of the two halves regenerated. In the pharate pupae no regeneration of the implanted halves took place. If the lapse of time between the transplantation and, the onset of metamorphosis (=onset of pharate pupae phase) was long enough by transplanting into young larvae (T4) or by repeatedly transferring into old larvae and subsequent transplantation into a final larval host, all the implanted halves were able to regenerate. Size of the Implanted Genital Organs After prolonging the in vivo culture in larval hosts by implanting into young larvae or repeatedly transferring into old larvae, it was found that the regenerated genitalia grew to the same size as the complete transplants, but the size of the complete transplants increased, if at all, only insignificantly. Duration of Development of the Hosts. Regeneration of one HO half implanted into a full-grown larva caused an average delay of further development of about 2 days. An additional delay was recorded when both halves had regenerated. However, no delay was observed when HO halves implanted into young (T4) larvae regenerated, and no delay occurred in the final hosts when the repeatedly transferred halves had reached a certain stage of regeneration. The developmental capacities of the tranplanted disks and the control of metamorphosis by regenerating disks are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848456
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  • 8
    Electronic Resource
    Electronic Resource
    Kinetics of sodiumd-glucose cotransport in bovine intestinal brush border vesicles (1984)
    Springer
    The journal of membrane biology 79 (1984), S. 41-51 
    Details
    ISSN: 1432-1424
    Keywords: glucose ; brush borders ; sodium cotransport ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Brush border membrane vesicles (BBMV) purified from steer jejunum were used to study the kinetics of sodiumd-glucose cotransport under voltage clamped, zero-trans conditions. When the initial rate of glucose transport (J gluc) was measured over a wide range of glucose concentrations ([S]=0.01–20mm), curvature of the Woolf-Augustinsson-Hofstee plots was seen, compatible with a diffusional and one major, high capacity (maximal transport rateJ max=5.8–8.8 nmol/mg·min) saturable system. Further studies indicated that changes incis [Na] altered theK t , but not theJ max, suggesting the presence of a rapid-equilibrium, ordered bireactant system with sodium adding first.Trans sodium inhibitedJ gluc hyperbolically. KCl-valinomycin diffusion potentials, inner membrane face positive, loweredJ gluc, while potentials of the opposite polarity raiseJ gluc. At low glucose concentrations ([S]〈0.05mm), a second, minor, high affinity transport system was indicated. Further evidence for this second saturable system was provided by sodium activation curves, which were hyperbolic when [S]=0.5mm, but were sigmoidal when [S]=.0.01mm. Simultaneous fluxes of22Na and [3H]glucose at 1mm glucose and 30mm NaCl yielded a cotransport-dependent flux ratio of 2∶1 sodium/glucose, suggestive of 1∶1 (Na/glucose) high capacity, low affinity system and a ∼3∶1 (Na/glucose) high affinity, low capacity system. Kinetic experiments with rabbit jejunal brush borders revealed two major Na-dependent saturable systems. Extravesicular (cis) Na changed theK t , but not theJ max of the major system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868525
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization of ion channels from Acetabularia plasma membrane in planar lipid bilayers (1993)
    Springer
    The journal of membrane biology 133 (1993), S. 145-160 
    Details
    ISSN: 1432-1424
    Keywords: Acetabularia ; K+ channels ; kinetics ; planar lipid bilayers ; voltage dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Plasma membrane from Acetabularia acetabulum was prepared by aqueous-polymer two-phase partitioning and incorporated into planar 1-palmitoyl-2-oleoyl phosphatidylethanolamine bilayers by stirring in the presence of a (cis∶trans) 325∶100 mm KCl gradient. Under these conditions five distinct K+-selective channels were observed which had unitary chord-conductances (determined between 30 mV either side of the reversal potential) and frequencies of incorporation (in parentheses) of 1,600 pS (26%), 485 pS (21%), 259 pS (53%), 140 pS (37%) and 27 pS (37%). Two Cl−-selective channels were also observed, which had unitary chord-conductances of 8 and 48 pS and were present in 21 and 16% of bilayers, respectively. The voltage dependencies of channel open probability (P o ), open-state time constant (τ o) and closed-state time constant (τ c) were determined for the 259, 140 and 27 pS K+ channels. The P o of all three channels increased with increasingly positive membrane potentials. Thus, since these channels were oriented with their extracellular face adjacent to the cis chamber, which was grounded, all would exhibit outward rectification in vivo. Changes in P o were effected by modulation of τ c in all channels, which shortened as membrane potentials became more positive, and also of τ o in the 140 and 27pS channels, which increased as membrane potentials became more positive. Extracellular (cis) KCl concentration (and/or the KCl gradient across the bilayer) affected the P o of all three K+ channels, shifting the P o /membrane potential relationship in the direction of the change in the potassium reversal potential. In all channels this was achieved largely by changes in τ c .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233795
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  • 10
    Electronic Resource
    Electronic Resource
    Protonophore anion permeability of the human red cell membrane determined in the presence of valinomycin (1988)
    Springer
    The journal of membrane biology 102 (1988), S. 225-234 
    Details
    ISSN: 1432-1424
    Keywords: erythrocytes ; valinomycin ; protonophore ; CCCP ; permeability ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A transport model for translocation of the protonophore CCCP across the red cell membrane has been established and cellular CCCP binding parameters have been determined. The time course of the CCCP redistribution across the red cell membrane, following a jump in membrane potential induced by valinomycin addition, has been characterized by fitting values of preequilibrium extracellular pHvs. time to the transport model. It is demonstrated, that even in the presence of valinomycin, the CCCP-anion is “well behaved,” in that the translocation can be described by simple electrodiffusion. The translocation kinetics conform to an Eyring transport model, with a single activation energy barrier, contrary to translocation across lipid bilayers, that is reported to follow a transport model with a plateau in the activation energy barrier. The CCCP anion permeability across the red cell membrane has been calculated to be close to 2.0×10−4 cm/sec at 37°C with small variations between donors. Thus the permeability of CCCP in the human red cell membrane deviates from that found in black lipid membranes, in which the permeability is found to be a factor of 10 higher.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01925716
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