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1.
Recovery cycles of the auditory brainstem responses were studied in the bottle-nosed dolphin, Tursiops truncatus, using paired acoustic clicks. The recovery time was longer if both clicks had identical spectra (50% recovery at 0.9 ms), as compared with that of different spectra (50% recovery at 0.35 ms). These results can explain a different recovery time of evoked responses after an artificial sound and after own locating one. 相似文献
2.
V. V. Popov A. Y. Supin V. O. Klishin 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,178(4):571-578
Simultaneous tone-tone masking in conjunction with the envelope-following response (EFR) recording was used to obtain tuning curves in dolphins (Turslops truncatus). The EFR was evoked by amplitude-modulated probes of various frequencies. A modulation rate of 600 Hz was found to fit the requirement to have a narrow spectrum and evoke EFR of large amplitude. Tuning curves were obtained within the frequency range from 11.2 to 110 kHz. The Q10 values of the obtained tuning curves varied from 12–14 at the 11.2 kHz center frequency to 17–20 at the 64–90 kHz frequencies.Abbreviations
ABR
auditory brainstem response
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EFR
envelope following response
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ERB
equivalent rectangular bandwidth 相似文献
3.
A. Y. Supin V. V. Popov V. O. Klishin 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1993,173(5):649-656
Tone-tone masking was used to determine auditory brain-stem response tuning curves in dolphins (Tursiops truncatus) in a simultaneous-masking paradigm. The Q
10 of the curves was as large as 16–19 in the frequency range 64–128 kHz. In the range 45–16 kHz, Q
10 decreased proportionally to the frequency with the bandwidth of the curves being constant, about 3.5–4 kHz at the 10-dB level. Tuning curves below 45 kHz are supposed to reflect broad spectral bandwidth of the probe's effective part which is no longer than 0.5 ms, irrespective of actual probe duration. Tuning curves above 64 kHz are supposed to reflect the real frequency tuning of the dolphin's auditory system.Abbreviations ABR
auditory brain stem response
- AP
action potential 相似文献
4.
Rokitskaya TI Klishin SS Severina II Skulachev VP Antonenko YN 《The Journal of membrane biology》2008,224(1-3):9-19
Mitochondria-targeted antioxidants consisting of a quinone part conjugated with a lipophilic cation via a hydrocarbon linker were previously shown to prevent oxidative damage to mitochondria in vitro and in vivo. In the present work, we studied the permeation of a series of compounds of this type across a planar bilayer phospholipid membrane. For this purpose, relaxation of the electrical current after a voltage jump was measured. With respect to the characteristic time of the relaxation process reflecting the permeation rate, hydrophobic cations can be ranked in the following series: 10(plastoquinonyl) decylrhodamine 19 (SkQR1) > 10-(6'-plastoquinonyl) decyltriphenylphosphonium (SkQ1) > 10-(6'-methylplastoquinonyl) decyltriphenylphosphonium (SkQ3) > 10-(6'-ubiquinonyl) decyltriphenylphosphonium (MitoQ). Thus, the permeation rate increased with (1) an increase in the size of the hydrophobic cation and (2) an increase in hydrophobicity of the quinone moiety. SkQ1 containing plastoquinone was shown to be more permeable through the membrane compared to MitoQ containing ubiquinone, which might be the reason for more pronounced beneficial action of SkQ1 in vitro and in vivo. The above approach can be recommended for the search for new antioxidants or other compounds targeted to mitochondria. 相似文献
5.
6.
Y. N. Antonenko A. V. Avetisyan L. E. Bakeeva B. V. Chernyak V. A. Chertkov L. V. Domnina O. Yu. Ivanova D. S. Izyumov L. S. Khailova S. S. Klishin G. A. Korshunova K. G. Lyamzaev M. S. Muntyan O. K. Nepryakhina A. A. Pashkovskaya O. Yu. Pletjushkina A. V. Pustovidko V. A. Roginsky T. I. Rokitskaya E. K. Ruuge V. B. Saprunova I. I. Severina R. A. Simonyan I. V. Skulachev M. V. Skulachev N. V. Sumbatyan I. V. Sviryaeva V. N. Tashlitsky J. M. Vassiliev M. Yu. Vyssokikh L. S. Yaguzhinsky A. A. Zamyatnin Jr. V. P. Skulachev 《Biochemistry. Biokhimii?a》2008,73(12):1273-1287
Synthesis of cationic plastoquinone derivatives (SkQs) containing positively charged phosphonium or rhodamine moieties connected
to plastoquinone by decane or pentane linkers is described. It is shown that SkQs (i) easily penetrate through planar, mitochondrial,
and outer cell membranes, (ii) at low (nanomolar) concentrations, posses strong antioxidant activity in aqueous solution,
BLM, lipid micelles, liposomes, isolated mitochondria, and cells, (iii) at higher (micromolar) concentrations, show pronounced
prooxidant activity, the “window” between anti- and prooxidant concentrations being very much larger than for MitoQ, a cationic
ubiquinone derivative showing very much lower antioxidant activity and higher prooxidant activity, (iv) are reduced by the
respiratory chain to SkQH2, the rate of oxidation of SkQH2 being lower than the rate of SkQ reduction, and (v) prevent oxidation of mitochondrial cardiolipin by OH·. In HeLa cells and human fibroblasts, SkQs operate as powerful inhibitors of the ROS-induced apoptosis and necrosis. For
the two most active SkQs, namely SkQ1 and SkQR1, C
1/2 values for inhibition of the H2O2-induced apoptosis in fibroblasts appear to be as low as 1·10−11 and 8·10−13 M, respectively. SkQR1, a fluorescent representative of the SkQ family, specifically stains a single type of organelles in
the living cell, i.e. energized mitochondria. Such specificity is explained by the fact that it is the mitochondrial matrix
that is the only negatively-charged compartment inside the cell. Assuming that the Δψ values on the outer cell and inner mitochondrial
membranes are about 60 and 180 mV, respectively, and taking into account distribution coefficient of SkQ1 between lipid and
water (about 13,000: 1), the SkQ1 concentration in the inner leaflet of the inner mitochondrial membrane should be 1.3·108 times higher than in the extracellular space. This explains the very high efficiency of such compounds in experiments on
cell cultures. It is concluded that SkQs are rechargeable, mitochondria-targeted antioxidants of very high efficiency and
specificity. Therefore, they might be used to effectively prevent ROS-induced oxidation of lipids and proteins in the inner
mitochondrial membrane in vivo.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.
Published in Russian in Biokhimiya, 2008, Vol. 73, No. 12, pp. 1589–1606.
This and the following four articles were written by the request of the Editorial Board of Biochemistry (Moscow). 相似文献
7.
The effect of Zn2+ on the rates of electron transfer and of voltage generation in the cytochrome bc1 complex (bc1) was investigated under excitation of Rhodobacter capsulatus chromatophores with flashing light. When added, Zn2+ retarded the oxidation of cytochrome b and allowed to monitor (at 561-570 nm) the reduction of its high potential heme bh (in the absence of Zn2+ this reaction was masked by the fast re-oxidation of the heme). The effect was accompanied by the deceleration of both the cytochrome c1 reduction (as monitored at 552-570 nm) and the generation of transmembrane voltage (monitored by electrochromism at 522 nm). At Zn2+ <100 μM the reduction of heme bh remained 10 times faster than other reactions. The kinetic discrepancy was observed even after an attenuated flash, when bc1 turned over only once. These observations (1) raise doubt on the notion that the transmembrane electron transfer towards heme bh is the main electrogenic reaction in the cytochrome bc1 complex, (2) imply an allosteric link between the site of heme bh oxidation and the site of cytochrome c1 reduction at the opposite side of the membrane, and (3) indicate that the internal redistribution of protons might account for the voltage generation by the cytochrome bc1 complex. 相似文献
8.
V. V. Popov A. Ya. Supin V. O. Klishin T. M. Bulgakova 《Doklady biological sciences》2003,392(1-6):393-396
9.
MS Muntyan DA Morozov SS Klishin NV Khitrin GY Kolomijtseva 《Biochemistry. Biokhimii?a》2012,77(8):917-924
The electrical potential on the membrane was measured in cells of strains AL2 and ALJ15 of the extremely alkaliphilic bacterium Thioalkalivibrio versutus using the penetrating cation tetraphenylphosphonium (TPP+) and a TPP+-selective electrode. The potentials were -228 ± 5 and -224 ± 5 mV, respectively, i.e. higher than in most alkaliphilic bacteria. Membrane potential in the cells was estimated by measuring the inner cell volume by two independent methods: (1) estimation of total cell volume by light microscopy and (2) estimation of the inner aqueous volume of the cells with allowance for the distribution difference of tritium labeled water penetrating through the membranes and a nonpenetrating colored protein. The inner cell volume was 2.4 ± 0.2 and 2.2 ± 0.1 μl/mg of cell protein by the two methods, respectively. Computer computation was used as an alternative to manual calculation to count the number of cells for estimation of total cell volume. 相似文献
10.
Vladimir P. Skulachev Yury N. Antonenko Dmitry A. Cherepanov Boris V. Chernyak Denis S. Izyumov Ludmila S. Khailova Sergey S. Klishin Galina A. Korshunova Konstantin G. Lyamzaev Olga Yu. Pletjushkina Vitaly A. Roginsky Tatiana I. Rokitskaya Fedor F. Severin Inna I. Severina Ruben A. Simonyan Maxim V. Skulachev Natalia V. Sumbatyan Evgeniya I. Sukhanova Vadim N. Tashlitsky Tatyana A. Trendeleva Renata A. Zvyagilskaya 《BBA》2010,1797(6-7):878-889
The present state of the art in studies on the mechanisms of antioxidant activities of mitochondria-targeted cationic plastoquinone derivatives (SkQs) is reviewed. Our experiments showed that these compounds can operate as antioxidants in two quite different ways, i.e. (i) by preventing peroxidation of cardiolipin [Antonenko et al., Biochemistry (Moscow) 73 (2008) 1273–1287] and (ii) by fatty acid cycling resulting in mild uncoupling that inhibits the formation of reactive oxygen species (ROS) in mitochondrial State 4 [Severin et al. Proc. Natl. Acad. Sci. USA 107 (2009), 663–668]. The quinol and cationic moieties of SkQ are involved in cases (i) and (ii), respectively. In case (i) SkQH2 interrupts propagation of chain reactions involved in peroxidation of unsaturated fatty acid residues in cardiolipin, the formed SkQ? being reduced back to SkQH2 by heme bH of complex III in an antimycin-sensitive way. Molecular dynamics simulation showed that there are two stable conformations of SkQ1 with the quinol residue localized near peroxyl radicals at C9 or C13 of the linoleate residue in cardiolipin. In mechanism (ii), fatty acid cycling mediated by the cationic SkQ moiety is involved. It consists of (a) transmembrane movement of the fatty acid anion/SkQ cation pair and (b) back flows of free SkQ cation and protonated fatty acid. The cycling results in a protonophorous effect that was demonstrated in planar phospholipid membranes and liposomes. In mitochondria, the cycling gives rise to mild uncoupling, thereby decreasing membrane potential and ROS generation coupled to reverse electron transport in the respiratory chain. In yeast cells, dodecyltriphenylphosphonium (С12TPP), the cationic part of SkQ1, induces uncoupling that is mitochondria-targeted since С12TPP is specifically accumulated in mitochondria and increases the H+ conductance of their inner membrane. The conductance of the outer cell membrane is not affected by С12TPP. 相似文献