Rhodobacter sphaeroide as a new biocatalysts were investigated in the asymmetric reduction of ketones to chiral alcohols. The cells were used in an aqueous system for the asymmetric reduction of acetophenone to prepar...Rhodobacter sphaeroide as a new biocatalysts were investigated in the asymmetric reduction of ketones to chiral alcohols. The cells were used in an aqueous system for the asymmetric reduction of acetophenone to prepare (S)-1-phenyl-ethanol by photo-electron-transfer reactions. It is found that higher product yield and product enantiomeric excess could be achieved. The results show that the enantiomer excess of the chiral alcohols was up to 99%(e.e.) and the yield is more than 90%. The effects of DCMU and the optimal reaction conditions on the reaction were investigated. The results show that the reaction was controlled by light completely, the optimal substrate concentration is 17.0 mmol/L, the optimal cell mass concentration is \{0.2 g/mL,\} the optimal pH is 7—8, the optimal reaction time was 72 h.展开更多
Spraying 1-2 mmol/L solution of NaHSO 3 on rice ( Oryza sativa L.) leaves resulted in the enhancement of net photosynthetic rate for more than three days. It was also observed that NaHSO 3 application caused incr...Spraying 1-2 mmol/L solution of NaHSO 3 on rice ( Oryza sativa L.) leaves resulted in the enhancement of net photosynthetic rate for more than three days. It was also observed that NaHSO 3 application caused increases both in ATP content in leaves and the millisecond_delayed light emission of leaves. The increase in net photosynthetic rate caused by NaHSO 3 treatment was similar to that by PMS (phenazine methosulfate) treatment. The grain yield of treated rice was enhanced approximately by 10% after duplicated application of NaHSO 3 in milk_ripening stage. It is suggested that the enhancement of photosynthesis by NaHSO 3 treatment resulted from the effect of increasing ATP supplement. Concomitant with an increase in the photosynthetic rate and ATP content in leaves, the transient increase in chlorophyll fluorescence after the termination of actinic light, which could be used as an index of the cyclic electron flow, was also enhanced by low concentration of NaHSO 3 treatment. Basing on these results it is proposed that the increase in rice photosynthesis caused by low concentrations of NaHSO 3 could be due to the stimulation of the cyclic electron flow around PSⅠ which in turn the enhancement of the coupled photophosphorylation and photosynthesis.展开更多
Pyropia yezoensis, an intertidal seaweed, experiences regular dehydration and rehydration with the tides. In this study, the responses of P. yezoensis to dehydration and rehydration under high and low CO2 concentratio...Pyropia yezoensis, an intertidal seaweed, experiences regular dehydration and rehydration with the tides. In this study, the responses of P. yezoensis to dehydration and rehydration under high and low CO2 concentrations （（600-700）×10^-6 and （40-80）×10^-6, named Group I and Group II respectively） were investigated. The thalli of Group I had a significantly higher effective photosystem II quantum yield than the thalli of Group II at 71% absolute water content （AWC）. There was little difference between thalli morphology, total Rubisco activity and total protein content at 100% and 71% AWC, which might be the basis for the normal performance of photosynthesis during moderate dehydration. A higher effective photosystem I quantum yield was observed in the thalli subjected to a low CO2 concentration during moderate dehydration, which might be caused by the enhancement of cyclic electron flow. These results suggested that P. yezoensis can directly utilize COz in ambient air during moderate dehydration.展开更多
The purpose of this study was to explore influence of abiotic factors, such as high temperature, water deficiency and high solar radiation on the photomembrane of grapevine leaves. Grapevine leaves were collected from...The purpose of this study was to explore influence of abiotic factors, such as high temperature, water deficiency and high solar radiation on the photomembrane of grapevine leaves. Grapevine leaves were collected from variety Rkatsiteli （Vitis vinifera） and placed at a temperature of ＋45 ℃ and ＋55 ℃ for 5 rain, respectively. The relative volume of water in leaves was gradually reduced to 50%, and then leaves were irradiated with 6,000 pmol/m2.s of white light. Changes provoked by stressful abiotie factors were determined using rapid and delayed chlorophyll fluorescence methods. It was shown that value of variable component of chlorophyll fluorescence （Fv）, intensity of electron transport between the photosystems （ETR）, intensity of expended electrons in carboxylation （ETRn） and oxygenation （ETRp） and index of non-photochemical quenching （NPQ）, allow studying molecular mechanisms of the impact of abiotic factors and the resulting damage degree. Based on delayed and rapid fluorescence data, it was demonstrated that temperature of ＋45 ℃ adversely affects oxygen production system and CO2 assimilation mechanisms, while at ＋55 ℃, the ETR decreases. Reduction of relative water volume in leaves up to 50%-55% leads to sharp reduction in ETR and inhibition of photosynthesis. In case of irradiation of leaves with high-intensity light of 6,000 μmol/m2.s, NPQ of light falling on a leaf increases, thus protecting photosynthesis apparatus from damage.展开更多
文摘Rhodobacter sphaeroide as a new biocatalysts were investigated in the asymmetric reduction of ketones to chiral alcohols. The cells were used in an aqueous system for the asymmetric reduction of acetophenone to prepare (S)-1-phenyl-ethanol by photo-electron-transfer reactions. It is found that higher product yield and product enantiomeric excess could be achieved. The results show that the enantiomer excess of the chiral alcohols was up to 99%(e.e.) and the yield is more than 90%. The effects of DCMU and the optimal reaction conditions on the reaction were investigated. The results show that the reaction was controlled by light completely, the optimal substrate concentration is 17.0 mmol/L, the optimal cell mass concentration is \{0.2 g/mL,\} the optimal pH is 7—8, the optimal reaction time was 72 h.
基金supported by the National Key Basic Research Program of China(973)(2012CB21500203)Dean Project of Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology,China(2013K009,2013Z001)~~
文摘Spraying 1-2 mmol/L solution of NaHSO 3 on rice ( Oryza sativa L.) leaves resulted in the enhancement of net photosynthetic rate for more than three days. It was also observed that NaHSO 3 application caused increases both in ATP content in leaves and the millisecond_delayed light emission of leaves. The increase in net photosynthetic rate caused by NaHSO 3 treatment was similar to that by PMS (phenazine methosulfate) treatment. The grain yield of treated rice was enhanced approximately by 10% after duplicated application of NaHSO 3 in milk_ripening stage. It is suggested that the enhancement of photosynthesis by NaHSO 3 treatment resulted from the effect of increasing ATP supplement. Concomitant with an increase in the photosynthetic rate and ATP content in leaves, the transient increase in chlorophyll fluorescence after the termination of actinic light, which could be used as an index of the cyclic electron flow, was also enhanced by low concentration of NaHSO 3 treatment. Basing on these results it is proposed that the increase in rice photosynthesis caused by low concentrations of NaHSO 3 could be due to the stimulation of the cyclic electron flow around PSⅠ which in turn the enhancement of the coupled photophosphorylation and photosynthesis.
基金Supported by the Science and Technology Strategic Pilot Program of Chinese Academy of Sciences(No.XDA11020404)the National High Technology Research and Development Program of China(863 Program)(No.2012AA100806)+1 种基金the Tianjin Natural Science Foundation(No.12JCZDJC22200)the Project for Developing Marine Economy by Science and Technology in Tianjin(No.KX2010-0005)
文摘Pyropia yezoensis, an intertidal seaweed, experiences regular dehydration and rehydration with the tides. In this study, the responses of P. yezoensis to dehydration and rehydration under high and low CO2 concentrations （（600-700）×10^-6 and （40-80）×10^-6, named Group I and Group II respectively） were investigated. The thalli of Group I had a significantly higher effective photosystem II quantum yield than the thalli of Group II at 71% absolute water content （AWC）. There was little difference between thalli morphology, total Rubisco activity and total protein content at 100% and 71% AWC, which might be the basis for the normal performance of photosynthesis during moderate dehydration. A higher effective photosystem I quantum yield was observed in the thalli subjected to a low CO2 concentration during moderate dehydration, which might be caused by the enhancement of cyclic electron flow. These results suggested that P. yezoensis can directly utilize COz in ambient air during moderate dehydration.
文摘The purpose of this study was to explore influence of abiotic factors, such as high temperature, water deficiency and high solar radiation on the photomembrane of grapevine leaves. Grapevine leaves were collected from variety Rkatsiteli （Vitis vinifera） and placed at a temperature of ＋45 ℃ and ＋55 ℃ for 5 rain, respectively. The relative volume of water in leaves was gradually reduced to 50%, and then leaves were irradiated with 6,000 pmol/m2.s of white light. Changes provoked by stressful abiotie factors were determined using rapid and delayed chlorophyll fluorescence methods. It was shown that value of variable component of chlorophyll fluorescence （Fv）, intensity of electron transport between the photosystems （ETR）, intensity of expended electrons in carboxylation （ETRn） and oxygenation （ETRp） and index of non-photochemical quenching （NPQ）, allow studying molecular mechanisms of the impact of abiotic factors and the resulting damage degree. Based on delayed and rapid fluorescence data, it was demonstrated that temperature of ＋45 ℃ adversely affects oxygen production system and CO2 assimilation mechanisms, while at ＋55 ℃, the ETR decreases. Reduction of relative water volume in leaves up to 50%-55% leads to sharp reduction in ETR and inhibition of photosynthesis. In case of irradiation of leaves with high-intensity light of 6,000 μmol/m2.s, NPQ of light falling on a leaf increases, thus protecting photosynthesis apparatus from damage.
