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111.
Yuichi Takeuchi Reiko Fukumoto Hirokazu Kasahara Takeshi Sakaki Mitsutoshi Kitao 《Plant cell reports》1995,14(9):566-570
Cotyledons excised from dark-grown seedlings of cucumber (Cucumis sativus L.) were cultured in vitro under UV radiation at different wavelengths, obtained by passage of light through cut-off filters with different transmittance properties. Growth and the synthesis of chlorophyll (Chl) in cotyledons were inhibited and malondialdehyde was accumulated upon irradiation at wavelengths below 320 nm. Exogenous application of scavengers of free radicals reversed the growth inhibition induced by UV-B. Measurement of the fluorescence of Chl a suggested that electron transfer in photosystems was affected by UV-B irradiation. On the basis of these results, the involvement is postulated of active species of oxygen in damages to thylakoid membranes and the growth inhibition that are induced by UV-B irradiation.Abbreviations Chl
chlorophyll
- Fm
maximal fluorescence (dark)
- Fm
maximal fluorescence (light)
- Fv
variable fluorescence (dark)
- Fv
variable fluorescence (light)
- MDA
malondialdehyde
- O2
Superoxide radical
- PS
photosystem
- qN
non-photochemical quenching of fluorescence
- qP
photochemical quenching of fluorescence
- UV-BBE
biologically effective UV-B radiation
- WL(T = 0.5)
wavelength at which 50% transmittance occurs 相似文献
112.
在96孔板中进行抗脂质过氧化的微量测定 总被引:8,自引:0,他引:8
以Fe2+/半胱氨酸诱导大鼠肝微粒体为基本模型,根据硫代巴比妥酸(TBA)反应原理,优化不同反应条件,建立了一种在96孔板上进行抗脂质过氧化测定的一步反应方法,该方法的灵敏度不低于传统的试管法,而且还具有微量、快速、简便等优点,特别适用于大规模筛选和研究抗氧化剂.此外,也可用于其它系统诱导的抗脂质过氧化的测定. 相似文献
113.
A. Alfsen C. de Paillerets K. Prasad P. K. Nandi R. E. Lippoldt H. Edelhoch 《European biophysics journal : EBJ》1984,11(2):129-136
Three characteristics have been demonstrated by the chemical analysis of bovine brain coated vesicles following removal of the coat proteins: a high protein content, a high cholesterol/lipid ratio and a high percentage of phosphatidylethanolamine amongst the phospholipids.The study of lipid bilayer organization and dynamics has been performed using the fluorescent probes pyrene and parinaric acid (cis and trans). This has allowed the study of both lateral mobility and rotational motion in the lipid bilayer of the coated and uncoated vesicles.Lateral mobility in the fluid phase of the lipid is slightly reduced by the presence of the clathrin coat, as indicated by the lower diffusion coefficient of pyrene in coated compared with uncoated vesicles.At all temperatures from 6° to 30°C, solid-phase domains, probed by trans parinaric acid, coexist with fluid-phase domains in the lipid bilayer. The temperature dependence of the parinaric acid lifetimes and of their amplitudes strongly suggests that the solid phase domains decrease in size with temperature, both in coated and uncoated vesicles.However, the difference in the value of the anisotropy at long times (r
), between coated and uncoated vesicles (a difference which is more pronounced for cis than for trans parinaric acid), indicates that the presence of the clathrin coat introduces disorder in the surrounding lipids, thus suggesting a possible role of the clathrin in the formation of the pits on the plasma membrane.Abbreviations CVs
coated vesicles
- UVs
uncoated vesicles
- TLC
thin layer chromatography
- DMSO
dimethylsulfoxide
- DPPC
dipalmitoylphosphatidylcholine
-
cis Pna
cis parinaric acid
- (9,11,13,15-cis-trans-trans-cis)
octadecatetraenoic acid
-
Trans Pna
Trans parinaric acid
- (9,11,13,15-all-trans)
octadecatetraenoic acid 相似文献
114.
A.G. MacDonald 《生物化学与生物物理学报:生物膜》1984,775(2):141-149
Tetrahymena was grown at up to 260 atm to see if the bilayer-ordering effect of pressure increased the proportion of unsaturated fatty acids in the membrane lipids. Both whole cells and microsomes showed no such change in their fatty acid composition. The most striking effect was seen in the former which showed a pressure-dependent increase in the proportion of C16:0 in relation to C16:Δ9. Homeoviscous adaptation to pressure does not appear to occur in this cell. 相似文献
115.
The reconstitution of chloroplast coupling factor ATP synthetase (CF1 · CF0) with thylakoid lipids by cholate dialysis produced vesicles that displayed higher steady-state anisotropy (rs) values for both 1,6-diphenyl-1,3,5-hexatriene (DPH) and trimethylammonium-diphenyl hexatriene fluorescence than the pure lipid alone. This is interpreted as meaning that the insertion of protein into the lipid bilayer brings about an increase in the ordering of acyl chains. This ordering effect became more obvious as the protein-to-lipid ratio was increased. Time-resolved decay analyses of DPH fluorescence anisotropy confirmed the conclusion drawn from the steady-state measurements, but further indicated that the dynamic motion of the probe was also slightly restricted after CF1 · CF0 incorporation. The restriction of DPH motion and the change in the half-angle for its cone of rotation was observed at relatively low protein-to-lipid ratios as compared with other reconstituted or biological membranes, suggesting that perhaps lipid-protein interactions occur with the inserted CF1 · CF0 complex. 相似文献
116.
The depression of the phase-transition temperature of dimyristoyl- and dipalmitoylphosphatidylcholine vesicles induced by phenol has been investigated by fluorescence polarization. This effect is strongly pH and concentration dependent. Only the uncharged phenol molecule influences the fluidity of the bilayer so that the interaction of phenol with the bilayer can be situated in the hydrophobic acyl chain region. Direct measurements of the partitioning of phenol in the phospholipid vesicles confirm these results and show a limited and concentration-dependent solubility. Phase-transition temperature depressions, obtained from thermodynamic analysis of partition coefficient measurement, are in good agreement with the experimental values. 相似文献
117.
Craig A. Halverson Alfred F. Esser Kenneth A. Souza 《Journal of cellular biochemistry》1978,8(2):129-138
Bacillus stearothermophilus cells vary the lipid fatty acid composition of cytoplasmic membranes with growth temperature. Spin label studies of such membranes have been interpreted to indicate lateral lipid phase separations at the growth temperature. We have now used freeze-fracture electron microscopy to confirm the spin label studies. Freeze-fracture faces of protoplasts indicate slight but distinct protein aggregation at the growth temperature. Aggregation increases rapidly with decreasing quench temperature in wild-type cells. In contrast we were unable to demonstrate extended protein segregation in membranes of a temperature-sensitive mutant that contains more than 58% branched fatty acids. Storage of protoplasts for prolonged times below the lipid phase transition results in the appearance of corrugated fracture faces with 300- to 500-Å repeat patterns, although this organism does not synthesize lecithins. 相似文献
118.
The fatty acid compositions of the ether lipid 1(3),2-diacylglyceryl-(3)-O-4′-(N,N,N-trimethyl)homoserine (DGTS) from Ochromonas danica a 相似文献
119.
Malak I. Shoukry 《Journal of biochemical and biophysical methods》1980,3(4):219-224
A simple method for extracting and purifying lipids from rat liver in a single step using nontoxic solvents is described. The method consists of homogenizing the puliverized tissue with a mixture of tricholotrifluoroethane (Cl2CF-CClF2) and isopropyl alcohol (). Just enough water is added to the lipid extract to produce a biphasic system. Pure lipid extract is obtained by isolating the lower layer from the aqueous upper phase which contains the non-lipid materials. The described method compares favourably with that of Folch et al., both quantitatively and qualitatively. The solvent system used also has the advantage of being less toxic than the widely used chloroform/methanol system, which makes it safer for prolonged use. The new method is simple, efficient and reproducible. 相似文献
120.
Comparative measurements were made of the fluidity of chloroplast thylakoids, total membrane lipids and polar lipids utilizing the order parameter and motion of spin labels.No significant differences were found in the fluidity of membranes or total membrane lipids from a wild type and a mutant barley (Hordeum vulgare chlorina f2 mutant) which lacks chlorophyll and a 25 000 dalton thylakoid polypeptide. Redistribution of intrinsic, exoplasmic face (EF) membrane particles by unstacking thylakoid membranes in low salt medium also had no effect on membrane fluidity. However, heating of isolated thylakoids decreased membrane fluidity.The fluidity of vesicles composed of membrane lipids is much greater than that of the corresponding membranes. Fluidity of the membranes, however, increased during greening indicating that the rigidity of the membranes, compared with that of total membrane lipids, is not caused by chlorophyll or its associated peptides. It is concluded that the restriction of motion in the acyl chains in the thylakoids is not caused by chlorophyll or the major intrinsic polypeptide but by some other protein components. 相似文献