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951.
Ma Hong Zhang Zheng-Dong Li Liang-Bi Ma Gui-Zhi Zhai Xiao-Jing Zhou Pei-Zhen 《植物分类学报:英文版》1986,24(6):428-433
Three species of evergreen Cephalotaxus (C. fortunei Hook. f., C. sinensis Li and
C. harringtonia cv. Fastigiata) were used as materials to study some functional properties of
chloroplasts. It is found that the oxygenevolving capacity of the chloroplasts from these plants
is inhibited but partial reaction of PS-II and effect of Mg2+ on energy distribution between
two photosystems are detectable during the winter. Seasonal effects on the functional properties
of chloroplasts from evergreen Cephalotaxus are similar to that of conifer chloroplasts.
The ratio between F685, F695 and F735 of fluorescence emission spectra at 77°K of chloroplasts is different among these three species. It is found by using SDS-PAGE that the number of polypeptide resolved from thylakoid membrane of C. harringtonia cv. Fastigiata substantially differs from that of C. fortunei Hook.f. and C. sinensis Li. The result shows that the
fluorescence emission spectrum feature and polypeptide composition of thylakoid membrane may
be used as a tool for systematics of the genus Cephalotaxus. 相似文献
952.
Compartmentalization of eukaryotic cells is created and maintained through membrane rearrangements that include membrane transport and organelle biogenesis. Three‐dimensional reconstructions with nanoscale resolution in combination with protein localization are essential for an accurate molecular dissection of these processes. The yeast Saccharomyces cerevisiae is a key model system for identifying genes and characterizing pathways essential for the organization of cellular ultrastructures. Electron microscopy studies of yeast, however, have been hampered by the presence of a cell wall that obstructs penetration of resins and cryoprotectants, and by the protein dense cytoplasm, which obscures the membrane details. Here we present an immuno‐electron tomography (IET) method, which allows the determination of protein distribution patterns on reconstructed organelles from yeast. In addition, we extend this IET approach into a correlative light microscopy‐electron tomography procedure where structures positive for a specific protein localized through a fluorescent signal are resolved in 3D. These new investigative tools for yeast will help to advance our understanding of the endomembrane system organization in eukaryotic cells. 相似文献
953.
Dagui Zhou Dandan Xie Fangcheng He Baoan Song Deyu Hu 《Bioorganic & medicinal chemistry letters》2018,28(11):2091-2097
A new concise and facile method was explored to synthesize a series of novel chalcone derivatives containing a purine and benzenesulfonamide moiety and their antiviral properties were evaluated against TMV and CMV. Biological assays indicated that several of the derivatives exhibited significant anti-TMV and anti-CMV activities in vivo. In particular, compound d2 displayed excellent inactivating activity against TMV, with the EC50 value of 51.65?μg/mL, which was better than that of ribavirin (150.45?μg/mL). Molecular docking showed that there are four hydrogen bonds between compound d2 and TMV coat protein (TMV-CP). Compound d2 demonstrated strong binding capacity to TMV-CP with Ka?=?1.58?×?105?L/mol and Kd?=?12.16?μM. These findings indicated that chalcone derivatives are worthy of further research and development as templates for new antiviral agents. 相似文献
954.
BackgroundTrace elements exhibit essential functions in many physiological processes. Thus, for research focusing on trace element homeostasis and metabolism analytical methods allowing for multi-element analyses are fundamental. Small sample amounts may be a big challenge in trace element analyses especially if also other end points want to be addressed in the same sample. Therefore, the aim of the present study was to examine trace elements (iron, copper, zinc, and selenium) in murine liver tissue prepared by a RIPA buffer-based lyses method.Methods and resultsAfter centrifugation, lysates and pellets were obtained and trace elements were analyzed with TXRF in liver lysates. The results were compared to that obtained by a standard microwave-assisted acidic digestion with subsequent ICP-MS/MS analysis of the same liver tissue, liver lysates, and remaining pellets. In addition, trace element concentrations, determined in murine serum with both methods, were compared. For serum samples, both TXRF and ICP-MS/MS provide similar and highly correlating results. Furthermore, in liver lysate samples prepared with RIPA buffer, comparable trace element concentrations were measured by TXRF as with the standard digestion technique and ICP-MS/MS. Only marginal amounts of trace elements were detected in the pellets.ConclusionTaken together, the results obtained by the present study indicate that the RIPA buffer-based method is suitable for sample preparation for trace element analyses via TXRF, at least for the here investigated murine liver samples. 相似文献
955.
Biogenesis of the photosynthetic apparatus in greening etiolated leaves of barley (Hordeum vulgare L) was investigated by an approach permitting investigation of this process under conditions that minimize differences in
plastid development. Distributions of barley leaves greening for 24 h as to chlorophyll content and of chloroplast grana as
to number of thylakoids were shown to be of a multimodal character. The shape of time-course curves of chlorophyll accumulation
in local sites of greening etiolated leaves was of a stepped or (at the end of greening) undulated character. The stepwise
accumulation of chlorophyll was accompanied by wave-like changes in chlorophyll b/a ratio, intensity of low-temperature chlorophyll fluorescence and photosynthetic activity with minima at the time points of
transition to accelerated chlorophyll accumulation. It is assumed that (1) development of the photosynthetic apparatus in
local sites of greening etiolated leaves occurs stepwise, from one steady level to another, but not as gradually as is generally
accepted, and (2) every separate step in development of the photosynthetic apparatus seems to begin with formation of photosystem
cores and to end with the synthesis of light-harvesting complexes.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
956.
A simple naphthol‐based fluorescent receptor 1 was prepared and evaluated for its fluorescence response to heavy metal ions. Receptor 1 exhibits an ‘off‐on‐type’ mode with high selectivity in the presence of Zn2+ ion. The selectivity of 1 for Zn2+ is the consequence of combined effects of chelation‐enhanced fluorescence (CHEF), C = N isomerization and π–π stacking interaction between the two naphthalene rings. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
957.
Can we measure terrestrial photosynthesis from space directly,using spectral reflectance and fluorescence? 总被引:2,自引:0,他引:2
J. GRACE C. NICHOL M. DISNEY† P. LEWIS† T. QUAIFE† P. BOWYER† 《Global Change Biology》2007,13(7):1484-1497
Attempts to estimate photosynthetic rate or gross primary productivity from remotely sensed absorbed solar radiation depend on knowledge of the light use efficiency (LUE). Early models assumed LUE to be constant, but now most researchers try to adjust it for variations in temperature and moisture stress. However, more exact methods are now required. Hyperspectral remote sensing offers the possibility of sensing the changes in the xanthophyll cycle, which is closely coupled to photosynthesis. Several studies have shown that an index (the photochemical reflectance index) based on the reflectance at 531 nm is strongly correlated with the LUE over hours, days and months. A second hyperspectral approach relies on the remote detection of fluorescence, which is a directly related to the efficiency of photosynthesis. We discuss the state of the art of the two approaches. Both have been demonstrated to be effective, but we specify seven conditions required before the methods can become operational. 相似文献
958.
In the present study, we documented the promising role of thyroid hormones status in animals in modulation of Na+–Pi transport activity in intestinal brush border membrane vesicles (BBMV) which was accompanied with alterations in BBM lipid
composition and fluidity. Augmentation of net Pi balance in hyperthyroid (Hyper-T) rats was fraternized with accretion of Pi transport across BBMV isolated from intestine of Hyper-T rats as compared to hypothyroid (Hypo-T) and euthyroid (Eu-T) rats
while Na+–Pi transport across BBMV was decreased in Hypo-T rats relative to Eu-T rats. Increment in Na+–Pi transport in intestinal BBMV isolated from Hyper-T rats was manifested as an increase in the maximal velocity (Vmax) of Na+–Pi transport system. Furthermore, BBMV lipid composition profile in intestinal BBM from Hyper-T was altered to that of Hypo-T
rats and Eu-T rats. The molar ratio of cholesterol/phospholipids was higher in intestinal BBM from Hypo-T rats. Fluorescence
anistropy of diphenyl hexatriene (rDPH) and microviscosity were significantly decreased in the intestinal BBM of Hyper-T rats
and decreased in Hypo-T rats as compared to Eu-T rats which corroborated with the alteration in membrane fluidity in response
to thyroid hormone status of animals. Therefore, thyroid hormone mediated change in membrane fluidity might play an important
role in modulating Na+–Pi transport activity of intestinal BBM. (Mol Cell Biochem 278: 195–202, 2005) 相似文献
959.
Antecedent studies have suggested that lipid composition and fluidity of cellular membranes of various organs are altered in response to thyroid hormone status. To date, the effects of thyroid hormone status on these parameters have not been examined in rat renal apical membrane in regard to sodium-dependent phosphate transport. In the present study, we determined the potential role of alterations in cortical brush-border membrane lipid composition and fluidity in modulation of Na+–Pi transport activity in response to thyroid hormone status. Thyroid hormone status influences the fractional excretion of Pi, which is associated with alteration in renal brush-border membrane phosphate transport. The increment in Na+–Pi transport in renal BBMV isolated from Hyper-T rats is manifested as an increase in the maximal velocity (Vmax) of Na+–Pi transport. Further, the cholesterol content was significantly increased in renal BBM of Hypo-T rats and decreased in Hyper-T rats as compared to the Eu-T rats. The molar ratio of cholesterol/phospholipids was also higher in renal BBM from hypo-T rats. Subsequently, fluorescence anisotropy of diphenyl hexatriene (rDPH) and microviscosity were significantly decreased in the renal BBM of the Hyper-T rats and increased in the Hypo-T rats as compared to Eu-T rats. The result of this study, therefore, suggest that alteration in renal BBM cholesterol, cholesterol/phospholipid molar ratio, and membrane fluidity play an important role in the modulation of renal BBM Na+–Pi transport in response to thyroid hormone status of animals. (Mol Cell Biochem 268: 75–82, 2005) 相似文献
960.
Plant growth, chlorophyll (Chl) content, photosynthetic gas exchange, ribulose-1,5-bisphosphate carboxylase (RuBPCO) enzyme
activity, and Chl fluorescence in radish (Raphanus sativus var. longipinnatus) plants were examined after turnip mosaic virus (TuMV) infection. Plant fresh mass, dry mass, Chl content, net photosynthetic
rate (P
N), transpiration rate (E), stomatal conductance (g
s), and RuBPCO activity were significantly lower in infected plants after 5 weeks of virus infection as compared to healthy
plants. The 5-week virus infection did not induce significant differences in intercellular CO2 concentration (C
i, photochemical efficiency of photosystem 2, PS2 (Fv/Fm), excitation capture efficiency of open PS2 reaction centres (Fv'/Fm'), effective quantum efficiency of photosystem 2 (ΔF/Fm'), and photochemical quenching (qP), but non-photochemical quenching (qN) and alternative electron sink (AES) were significantly enhanced. Thus the decreased plant biomass of TuMV-infected plants
might be associated with the decreased photosynthetic activity mainly due to reduced RuBPCO activity. 相似文献