Remobilisation of nitrate in plants, especially in vacuole of plant, is mostly related to the qua- lity of agricultural products and the high nitrogen use efficiency in plants. Ion-selective microelectrodes offer a n...Remobilisation of nitrate in plants, especially in vacuole of plant, is mostly related to the qua- lity of agricultural products and the high nitrogen use efficiency in plants. Ion-selective microelectrodes offer a non-destructive and non-interruptive method to measure NO 3 gradients and electric potential differences across both the plasma membrane and tonoplast. Thus, a double-barrelled microelectrode backfilled with a membrane sensor for NO 3 embedded in poly vinyl chloride (PVC) can record the NO 3 activity in cytoplasm and vacuole of a cell. This paper presented how to make this kind of microelectrode and how to do the intracellular measurements on intact plants. Our result showed that nitrate activity was about 2.7 mmol L 1 in cytoplasm while 70 mmol L 1 in vacuole, which implicated that vacuole was a pool of nitrate in plants.展开更多
A new PVC matrix membrane double-barreled calcium ion-selective microelectrode based on liquid ion exchanger has been designed and constructed.The tip diameter of about 2.5μm as well as lower selectivity coefficients...A new PVC matrix membrane double-barreled calcium ion-selective microelectrode based on liquid ion exchanger has been designed and constructed.The tip diameter of about 2.5μm as well as lower selectivity coefficients for K+,Na and Mg2+are adequate for in-tracellular measurements of Ca activities.The inner wall of the selective channel was made to be hydrophobic by treatment withalkyl-alcohols.By means of this microelectrode some physiologicalphenomena related to Ca2+activities have been studied,and Caconcentrations in clinical microsamples have also been determined.展开更多
Plants need to be efficient in nutrient management, especially when they face the temporal nutrient defficiencies. Understanding how crops respond to nitrogen （N） starvation would help in the selection of crop culti...Plants need to be efficient in nutrient management, especially when they face the temporal nutrient defficiencies. Understanding how crops respond to nitrogen （N） starvation would help in the selection of crop cultivars more tolerant to N deficiency. In the present work, the physiological responses of two wheat cultivars, Yannong 19 （YN） and Qinmai 11 （QM）, to N starvation conditions were investigated. The two cultivars differed in biomass and N rearrangement between shoots and roots during N starvation. QM allocated more N to roots and exhibited higher root/shoot biomass ratio than YN. However, tissue measurement indicated that both cultivars had similar nitrate content in leaves and roots and similar remobilization rate in roots. Microelectrode measurement showed that vacuolar nitrate activity （concentration） in roots of QM was lower than that in roots of YN, especially in epidermal cells. Nitrate remobilization rates from root vacuoles of two cultivars were also identical. Moreover, vacuolar nitrate remobilization rate was proportional to vacuolar nitrate activity. During N starvation, nitrate reductase activity （NRA） was decreased but there were no significant differences between the two cultivars. Nitrate efflux from roots reduced after external N removal and QM seemed to have higher nitrate efflux rate.展开更多
基金supported by the National Natural Science Foundation of China(30270790).
文摘Remobilisation of nitrate in plants, especially in vacuole of plant, is mostly related to the qua- lity of agricultural products and the high nitrogen use efficiency in plants. Ion-selective microelectrodes offer a non-destructive and non-interruptive method to measure NO 3 gradients and electric potential differences across both the plasma membrane and tonoplast. Thus, a double-barrelled microelectrode backfilled with a membrane sensor for NO 3 embedded in poly vinyl chloride (PVC) can record the NO 3 activity in cytoplasm and vacuole of a cell. This paper presented how to make this kind of microelectrode and how to do the intracellular measurements on intact plants. Our result showed that nitrate activity was about 2.7 mmol L 1 in cytoplasm while 70 mmol L 1 in vacuole, which implicated that vacuole was a pool of nitrate in plants.
基金Projects supported by the science Fund of the Chinese Academy of Sciences.
文摘A new PVC matrix membrane double-barreled calcium ion-selective microelectrode based on liquid ion exchanger has been designed and constructed.The tip diameter of about 2.5μm as well as lower selectivity coefficients for K+,Na and Mg2+are adequate for in-tracellular measurements of Ca activities.The inner wall of the selective channel was made to be hydrophobic by treatment withalkyl-alcohols.By means of this microelectrode some physiologicalphenomena related to Ca2+activities have been studied,and Caconcentrations in clinical microsamples have also been determined.
基金supported by grants from the National Basic Research Program of China (973 Program, 2007CB109303)the National Natural Science Foundation of China (30871588 and 31000934)the Yangzhou University 'Crop Science' Project funded by the Priority Program of Jiangsu on Higher Education Institutions, China
文摘Plants need to be efficient in nutrient management, especially when they face the temporal nutrient defficiencies. Understanding how crops respond to nitrogen （N） starvation would help in the selection of crop cultivars more tolerant to N deficiency. In the present work, the physiological responses of two wheat cultivars, Yannong 19 （YN） and Qinmai 11 （QM）, to N starvation conditions were investigated. The two cultivars differed in biomass and N rearrangement between shoots and roots during N starvation. QM allocated more N to roots and exhibited higher root/shoot biomass ratio than YN. However, tissue measurement indicated that both cultivars had similar nitrate content in leaves and roots and similar remobilization rate in roots. Microelectrode measurement showed that vacuolar nitrate activity （concentration） in roots of QM was lower than that in roots of YN, especially in epidermal cells. Nitrate remobilization rates from root vacuoles of two cultivars were also identical. Moreover, vacuolar nitrate remobilization rate was proportional to vacuolar nitrate activity. During N starvation, nitrate reductase activity （NRA） was decreased but there were no significant differences between the two cultivars. Nitrate efflux from roots reduced after external N removal and QM seemed to have higher nitrate efflux rate.
