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861.
Experiments on cyanobacterial cultures showed that initial exposure to copper at concentrations of 0.01–0.05 mg/l not only has a direct toxic effect, but also significantly modifies the copper tolerance of cyanobacteria for repeated exposure. The response to repeated exposure and the mechanism of tolerance depend on the strength of the initial effect of copper and the extent of heterogeneity of the initial cyanobacterial population. 相似文献
862.
863.
V. N. Barai A. I. Zinchenko L. M. Zalashko L. A. Eroshevskaya I. A. Mikhailopulo 《Biotechnology letters》1995,17(6):599-602
Summary The title compound was prepared by a three-stage enzymatic procedure consisting of (i) RNA hydrolysis to a mixture of ribonucleosides using intact mycelium of Spicaria violacea, (ii) transribosylation of exogenous adenine employing whole cells of Escherichia coli as a biocatalyst, and (iii) conversion of formed adenosine into ATP by the enzymes of alcohol fermentation and the kinases extracted from baker's yeast. 相似文献
864.
Biophysics - The relationship between pandemic morbidity and the shared participation of a pandemic variant in epidemic process has been studied based on the example of the first pandemic wave of... 相似文献
865.
Immunochemical analysis of the cAMP-dependent protein kinase regulatory subunit type II was performed with the use of two rabbit antisera elicited to a free R-subunit from pig brain and to a RcAMP complex. Quantitative precipitation of the homogeneous antigen revealed six determinants on the R-molecule. Of these at least one is localized in the R-fragment (37 kD), the others--in the N-terminal part of the R-molecule. The antigenic determinants seem to be remoted from the cAMP-binding centers, since the attachment of the affinity purified antibody Fab-fragments to the R-subunit did not influence the cAMP-binding activity of the latter. The antibodies to RcAMP caused dissociation of the holoenzyme. The antibody Fab-fragment binding to the R-subunit prevented its association with the catalytic subunit. The results of immunochemical analysis suggest that the R-subunit adopts different conformations when bound to cAMP or to the catalytic subunit. 相似文献
866.
R D Keynes N G Greeff I C Forster J M Bekkers 《Proceedings. Biological sciences / The Royal Society》1991,246(1316):135-140
The effect of tetrodotoxin (TTX) on the sodium gating current in the squid giant axon was examined by recording the current that flowed at the pulse potential at which the ionic current fell to zero, first in the absence and then in the presence of TTX. The addition of 1 microM TTX to the bathing solution had no consistent effect on the size of the initial peak of the gating current, but resulted in small changes in the timecourse of its subsequent relaxation which were mainly caused by a reduction of about one quarter in the component that has a delayed onset and may possibly arise from changes in the state of ionization of groups in the channel wall when the lumen fills with water. Our findings suggest that the binding of TTX at the outer face of the sodium channel does not interfere with the mechanisms of activation and inactivation by the voltage sensors, but has an allosteric effect on the access of internal cations to the inside of the channel. 相似文献
867.
868.
869.
I M Izrail'tian N N Alipov O L Lepetiukh A V Sokolov A G Mikerina O V Komarova 《Biulleten' eksperimental'no? biologii i meditsiny》1992,114(7):3-5
In acute experiments on 21 cats it was proved that the change of afferent impulse on vagus nerves by means of either freeze-block or electrostimulation of their central ends results in differential reflex influences on rhythm and force of the cardiac contractions caused by sympathetic nervous system. The cut of the lower cardiac nerves may cause 'break-up' of the observed reflex, removing or inverting its ino- or chronotropy component. The given phenomenon was revealed in the experiments with high arterial pressure and with absence of tonic chronotropy influences of the left lower cardiac nerve. 相似文献
870.