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1.
Measurements of the coefficient of water molecules self-diffusion (D) and the time of spin-lattice relaxation (T
1) in prosenchyme (elongated) plant cells, whose length significantly exceeding their transverse size, show that the orientation of plant tissues in the H
0field significantly affects the measured parameters. We conclude that this effect should be taken into account in experiments on the measurement of self-diffusion coefficients and time of proton spin-lattice relaxation in plant tissues containing prosenchyme cells. 相似文献
2.
Positive selection is a general phenomenon in the evolution of abalone sperm lysin 总被引:36,自引:21,他引:15
Lysin is a 16kDa acrosomal protein used by abalone sperm to create a hole
in the egg vitelline envelope (VE). The interaction of lysin with the VE is
species-selective and is one step in the multistep fertilization process
that restricts heterospecific (cross-species) fertilization. For this
reason, the evolution of lysin could play a role in establishing prezygotic
reproductive isolation between species. Previously, we sequenced sperm
lysin cDNAs from seven California abalone species and showed that positive
Darwinian selection promotes their divergence. In this paper an additional
13 lysin sequences are presented representing species from Japan, Taiwan,
Australia, New Zealand, South Africa, and Europe. The total of 20 sequences
represents the most extensive analysis of a fertilization protein to date.
The phylogenetic analysis divides the sequences into two major clades, one
composed of species from the northern Pacific (California and Japan) and
the other composed of species from other parts of the world. Analysis of
nucleotide substitution demonstrates that positive selection is a general
process in the evolution of this fertilization protein. Analysis of
nucleotide and codon usage bias shows that neither parameter can account
for the robust data supporting positive selection. The selection pressure
responsible for the positive selection on lysin remains unknown.
相似文献
3.
Recent data on the proton-translocating activity of b cytochromes in chromatophores of purple bacteria and their arrangement in the photosynthetic redox chain are discussed. These data appear to support the concept of the b50 and b-90 cytochrome doublet spanning the membrane. Current schemes of H+ transport by b cytochromes are considered, and the scheme of H+ translocation by cytochrome b50 taking up H+ at the outer side of the membrane and a quinone delivering them from this cytochrome to the inner space of the chromatophore is favored as the most probable in the light of recent findings. This scheme is applicable both to Crofts' linear model of the redox chain and to Mitchell's Q cycle. Kinetic discrepancies between H+ uptake and cytochrome b50 reduction at high ambient redox potentials are interpreted in terms of a special, cytochrome b50-independent, yet Rieske FeS-protein-dependent mode of H+ transport. 相似文献
4.
L.A. Drachev V.N. Frolov A.D. Kaulen A.A. Kondrashin V.D. Samuilov A.Yu. Semenov V.P. Skulachev 《BBA》1976,440(3):637-660
Lipoprotein complexes, containing (1) bacteriochlorophyll reaction centers, (2) bacteriochlorophyll light-harvesting antenna or (3) both reaction centers and antenna, have been isolated from chromatophores of non-sulphur purple bacteria Rhodospirillum rubrum by detergent treatments. The method of reconstituting the proteoliposomes containing these complexes is described. Being associated with planar azolectin membrane, proteoliposomes as well as intact chromatophores were found to generate a light-dependent transmembrane electric potential difference measured by Ag/AgCl electrodes and voltmeter. The direction of the electric field in proteoliposomes can be regulated by the addition of antenna complexes to the reconstitution mixture. The reaction center complex proteoliposomes generate an electric field of a direction opposite to that in chromatophores, whereas proteoliposomes containing reaction center complexes and a sufficient amount of antenna complexes produce a potential difference as in chromatophores. ATP and inorganic pyrophosphate, besides light, were shown to be usable as energy sources for electric generation in chromatophores associated with planar membrane. 相似文献
5.
Samuilov VD Lagunova EM Dzyubinskaya EV Izyumov DS Kiselevsky DB Makarova YV 《Biochemistry. Biokhimii?a》2002,67(6):627-634
The effect of cyanide, an apoptosis inducer, on pea leaf epidermal peels was investigated. Illumination stimulated the CN–-induced destruction of guard cells (containing chloroplasts and mitochondria) but not of epidermal cells (containing mitochondria only). The process was prevented by antioxidants (-tocopherol, 2,5-di-tret-butyl-4-hydroxytoluene, and mannitol), by anaerobiosis, by the protein kinase C inhibitor staurosporine, and by cysteine and serine protease inhibitors. Electron acceptors (menadione, p-benzoquinone, diaminodurene, TMPD, DCPIP, and methyl viologen) suppressed CN–-induced apoptosis of guard cells, but not epidermal cells. Methyl viologen had no influence on the removal of CN–-induced nucleus destruction in guard cells under anaerobic conditions. The light activation of CN–-induced apoptosis of guard cells was suppressed by DCMU (an inhibitor of the electron transfer in Photosystem II) and by DNP-INT (an antagonist of plastoquinol at the Qo site of the chloroplast cytochrome b
6
f complex). It is concluded that apoptosis initiation in guard cells depends on the simultaneous availability of two factors, ROS and reduced quinones of the electron transfer chain. The conditions for manifestation of programmed cell death in guard and epidermal cells of the pea leaf were significantly different. 相似文献
6.
A spin probe method was used to study microviscosity of aqueous medium in embryos and endosperm of maize (Zea mays L.) seeds after their irradiation with a Lvov-1 Elektronika laser device. Based on parameters of electron spin resonance (ESR) spectra of nitroxyl radicals (probes) absorbed by imbibing seeds during water uptake, correlation times τC were determined for the rotational diffusion of probes in embryos and endosperm of seeds. The τC values were found smaller in embryos of irradiated seeds than in untreated seeds; the dependence of τC on the duration of seed imbibition was determined. It is concluded that laser irradiation of seeds decreases the microviscosity of aqueous medium in embryo cells and elevates the mobility of the probes. Effect of laser irradiation on τC in seed endosperm was less pronounced but also led to the increase in probe mobility. 相似文献
7.
Dzyubinskaya EV Kiselevsky DB Lobysheva NV Shestak AA Samuilov VD 《Biochemistry. Biokhimii?a》2006,71(10):1120-1127
Cyanide is an apoptosis inducer in stoma guard cells from pea leaf epidermis. Unlike CN-, the uncoupler of oxidative and photosynthetic phosphorylation carbonyl cyanide m-chlorophenylhydrazone (CCCP), the combination of CCCP, 3-(3 ,4 -dichlorophenyl)-1,1-dimethylurea (DCMU), benzylhydroxamate (BH), myxothiazol, antimycin A, and a glycolysis inhibitor 2-deoxyglucose (DG) did not induce destruction of guard cell nuclei for 20 h of incubation of epidermal peels in the light. DCMU prevented the effect of CN- as a programmed cell death (PCD) inducer. CCCP, the combination of DCMU and CCCP, or the combination of DCMU, CCCP, BH, myxothiazol, antimycin A, and DG supplemented by CN- caused destruction of cell nuclei; the number of the cells lacking nuclei in this case was higher than with CN- alone. DG and CCCP caused cell destruction after longer incubation of the isolated epidermis - after 2 days and to a greater degree after 4 days. The effect of DG and CCCP was reduced by illumination. Cell destruction during long-term incubation was prevented by the combination of DG and CCCP. From data of electron microscopy, DCMU and dinitrophenyl ester of iodonitrothymol (DNP-INT) prevented apoptotic changes of the nuclear ultrastructure induced by CN-. The suppression of the destruction of the guard cell nuclei under combined action of DG and CCCP was apparently caused by switching of cell death from PCD to necrosis. Thus, the type of cell death - via apoptosis or necrosis - is controlled by the level of energy provision. 相似文献
8.
9.
The uncoupler of photophosphorylation FCCP inhibits the light-induced changes in absorbancy forRhodospirillum rubrum, Ectothiorhodospira shaposhnikovii andChromatium minutissimum cells in anaerobic conditions. These changes are associated with the shifts of bacteriochlorophyll absorption bands. The superposition of these spectral shifts and the photobleaching of reaction centers P890 is observed in aerobic conditions.The light-induced shifts of bacteriochlorophyll absorption bands are suggested to be due to the electrochemical transmembrane potential and local electric field arising as a result of the primary separation of opposite charges.Abbreviations FCCP
carbonylcyanide-p-trifluoromethoxy phenyl-hydrazone
- TMPD
tetramethyl-p-phenylenediamine 相似文献
10.
Vasil'ev LA Vorobyov AA Dzyubinskaya EV Nesov AV Shestak AA Samuilov VD 《Biochemistry. Biokhimii?a》2007,72(5):572-577
Destruction of guard cell nuclei in epidermis isolated from leaves of pea, maize, sunflower, and haricot bean, as well as destruction of cell nuclei in leaves of the aquatic plants waterweed and eelgrass were induced by cyanide. Destruction of nuclei was strengthened by illumination, prevented by the antioxidant alpha-tocopherol and an electron acceptor N,N,N ,N -tetramethyl-p-phenylenediamine, and removed by quinacrine. Photosynthetic O2 evolution by the leaf slices of a C3 plant (pea), or a C4 plant (maize) was inhibited by CN- inactivating ribulose-1,5-bisphosphate carboxylase, and was renewed by subsequent addition of the electron acceptor p-benzoquinone. 相似文献