There were four doublets in the Mssbauer spectrum of cucumber (Cucumis sativus L.) photosystemⅡ (PSⅡ) particles. According to the value of isomer shift and quadrupole splitting, they represented oxidized cytochrome ...There were four doublets in the Mssbauer spectrum of cucumber (Cucumis sativus L.) photosystemⅡ (PSⅡ) particles. According to the value of isomer shift and quadrupole splitting, they represented oxidized cytochrome b559 (Cyt_b559), reduced Cyt_b559, Fe 3+ _quinone (Q) complex, and Fe 2+ _Q complex respectively. After water_stress, the electron transport rate between Q A (primary quinone electron acceptor of PSⅡ)/Q B(secondary quinone electron acceptor of PSⅡ) was affected and the absorption doublets of Fe 2+ disappeared, suggesting that the reduced Cyt_b559 and Fe 2+ _Q complex had been oxidized. The results indicated that water_stress had changed the redox status of iron in the iron_quinone complex. Iron took part in electron transport through the change from a state of reduction to oxidation.展开更多
PS/SiO2 particles with core-shell structure were synthesized by coating silica on surface of polystyrene(PS) colloidal particles.The reaction parameters,such as initial tetraethyl orthosilicate(TEOS) concentration,wat...PS/SiO2 particles with core-shell structure were synthesized by coating silica on surface of polystyrene(PS) colloidal particles.The reaction parameters,such as initial tetraethyl orthosilicate(TEOS) concentration,water concentration and reaction temperature,have been investigated to control the thickness of silica shells.The shell thickness was prepositional to the square root of the initial concentration of TEOS and first increased with increasing water concentration,reached a maximum at about 2.0 mol/L and then started decreasing beyond that concentration.It was also found that the shell thickness decreased firstly with the reaction temperature added,then tended to a constant.The so-synthesized PS/SiO2 core-shell particles were directly crystallized into 3-D ordered thin film,then sintered at 570℃ into the ordered macroporous thin film.Compared with the conditional method,the present approach avoids repeatedly filling the precursor in the templetes and save time more.展开更多
Fe_3O_4/PS magnetic particles with core/shell structure has been prepared in the presence of Fe3O4 magnetic fluid in ethanol/water mixture.Magnetic particles with diameter size range from 5. 54 t0 187. 32 μm were obt...Fe_3O_4/PS magnetic particles with core/shell structure has been prepared in the presence of Fe3O4 magnetic fluid in ethanol/water mixture.Magnetic particles with diameter size range from 5. 54 t0 187. 32 μm were obtained by different reaction conditions.Some parameters such as ethanol, PEG and monomer which affect particle size diameter and size distribution are discussed briefly in this paper.展开更多
The protecting effect of histidine on the photodamage of pigments and proteins of the isolated PSⅠ particles from the chloroplast of Spinacia oleracea L. during the strong illumination (2 300 μmol·m -2 ...The protecting effect of histidine on the photodamage of pigments and proteins of the isolated PSⅠ particles from the chloroplast of Spinacia oleracea L. during the strong illumination (2 300 μmol·m -2 ·s -1 ) was studied by spectroscopy and SDS_PAGE. The absorbance of PSⅠ particles decreased during the strong illumination treatment, but the decrease would be slowed down in the presence of externally added histidine after 30 min illumination. The decrease of CD (circular dichroism) signal intensities of PSⅠ particles also was slowed down by the added histidine after about 10 min illumination. The retarded protecting effect of the added histidine on the photobleaching of pigments of PSⅠ complexes implied that the mechanisms of photoinhibition of isolated PSⅠ complexes are different from early stage to later stage during the strong illumination treatment. In addition, the added histidine suppressed the decrease of 77 K fluorescence yield of PSⅠ particles during the illumination. SDS_PAGE showed that the added histidine not only protected the reaction center proteins of PSⅠ particles, but also protected other subunits of PSⅠ particles from degradation.展开更多
Apical membrane recycling has been proposed to be important for normal hair cell function. The current study reports an in vitro work that demonstrates the presence of phosphatidylserine (PS) and PS-positive vesicles ...Apical membrane recycling has been proposed to be important for normal hair cell function. The current study reports an in vitro work that demonstrates the presence of phosphatidylserine (PS) and PS-positive vesicles labeled by Annexin V in the apical portion of hair cells. The following characteristics of the PS-positive vesicles were noticed using scanning confocal fluorescence microscopy:(1) variable sizes around 200 nm; (2) variable distribution patterns (either uniformly along individual stereocilia in the hair bundle or irregular) in the stereocilia from cell to cell; (3) variable sizes and numbers at locations along the border of the cuticular plate (CP), with a large number of them located at the vestigal kinocilial location; (4) motility with some of the vesicles during the observation period; (5) increase in PS labeling and the number of PS-positive vesicles after loud sound stimulation; and (6) decreased PS labeling and PS-positive vesicle numbers following treatment with LY-294002, a PI3 -kinase inhibitor. These results suggest that the presence of PS-positive vesicles at the apical area of hair cells may be indicative of vesicle shedding or transportation of a protein or rafts.展开更多
文摘There were four doublets in the Mssbauer spectrum of cucumber (Cucumis sativus L.) photosystemⅡ (PSⅡ) particles. According to the value of isomer shift and quadrupole splitting, they represented oxidized cytochrome b559 (Cyt_b559), reduced Cyt_b559, Fe 3+ _quinone (Q) complex, and Fe 2+ _Q complex respectively. After water_stress, the electron transport rate between Q A (primary quinone electron acceptor of PSⅡ)/Q B(secondary quinone electron acceptor of PSⅡ) was affected and the absorption doublets of Fe 2+ disappeared, suggesting that the reduced Cyt_b559 and Fe 2+ _Q complex had been oxidized. The results indicated that water_stress had changed the redox status of iron in the iron_quinone complex. Iron took part in electron transport through the change from a state of reduction to oxidation.
基金Supported by the National Natural Science Foundation of China(No.:20221603)
文摘PS/SiO2 particles with core-shell structure were synthesized by coating silica on surface of polystyrene(PS) colloidal particles.The reaction parameters,such as initial tetraethyl orthosilicate(TEOS) concentration,water concentration and reaction temperature,have been investigated to control the thickness of silica shells.The shell thickness was prepositional to the square root of the initial concentration of TEOS and first increased with increasing water concentration,reached a maximum at about 2.0 mol/L and then started decreasing beyond that concentration.It was also found that the shell thickness decreased firstly with the reaction temperature added,then tended to a constant.The so-synthesized PS/SiO2 core-shell particles were directly crystallized into 3-D ordered thin film,then sintered at 570℃ into the ordered macroporous thin film.Compared with the conditional method,the present approach avoids repeatedly filling the precursor in the templetes and save time more.
文摘Fe_3O_4/PS magnetic particles with core/shell structure has been prepared in the presence of Fe3O4 magnetic fluid in ethanol/water mixture.Magnetic particles with diameter size range from 5. 54 t0 187. 32 μm were obtained by different reaction conditions.Some parameters such as ethanol, PEG and monomer which affect particle size diameter and size distribution are discussed briefly in this paper.
文摘The protecting effect of histidine on the photodamage of pigments and proteins of the isolated PSⅠ particles from the chloroplast of Spinacia oleracea L. during the strong illumination (2 300 μmol·m -2 ·s -1 ) was studied by spectroscopy and SDS_PAGE. The absorbance of PSⅠ particles decreased during the strong illumination treatment, but the decrease would be slowed down in the presence of externally added histidine after 30 min illumination. The decrease of CD (circular dichroism) signal intensities of PSⅠ particles also was slowed down by the added histidine after about 10 min illumination. The retarded protecting effect of the added histidine on the photobleaching of pigments of PSⅠ complexes implied that the mechanisms of photoinhibition of isolated PSⅠ complexes are different from early stage to later stage during the strong illumination treatment. In addition, the added histidine suppressed the decrease of 77 K fluorescence yield of PSⅠ particles during the illumination. SDS_PAGE showed that the added histidine not only protected the reaction center proteins of PSⅠ particles, but also protected other subunits of PSⅠ particles from degradation.
文摘Apical membrane recycling has been proposed to be important for normal hair cell function. The current study reports an in vitro work that demonstrates the presence of phosphatidylserine (PS) and PS-positive vesicles labeled by Annexin V in the apical portion of hair cells. The following characteristics of the PS-positive vesicles were noticed using scanning confocal fluorescence microscopy:(1) variable sizes around 200 nm; (2) variable distribution patterns (either uniformly along individual stereocilia in the hair bundle or irregular) in the stereocilia from cell to cell; (3) variable sizes and numbers at locations along the border of the cuticular plate (CP), with a large number of them located at the vestigal kinocilial location; (4) motility with some of the vesicles during the observation period; (5) increase in PS labeling and the number of PS-positive vesicles after loud sound stimulation; and (6) decreased PS labeling and PS-positive vesicle numbers following treatment with LY-294002, a PI3 -kinase inhibitor. These results suggest that the presence of PS-positive vesicles at the apical area of hair cells may be indicative of vesicle shedding or transportation of a protein or rafts.
