In order to study the diurnal variation of soil CO2 effiux from temperate meadow steppes in Northeast China, and determine the best time for observation, a field experiment was conducted with a LI-6400 soil CO2 flux s...In order to study the diurnal variation of soil CO2 effiux from temperate meadow steppes in Northeast China, and determine the best time for observation, a field experiment was conducted with a LI-6400 soil CO2 flux system under five typical plant communi- ties （Suaeda glauca （Sg）, Chloris virgata （Cv）, Puecinellia distans （Pd）, Leymus chinensis （Lc） and Phragmites australis （Pa）） and an alkali-spot land （As） at the meadow steppe of western Songnen Plain. The results showed that the diurnal variation of soil CO2 effiux exhibited a single peak curve in the growing season. Diurnal maximum soil respiration （Rs） often appeared between 1 1：00 and 13：00, while the minimum occurred at 21：00-23：00 or before dawn. Air temperature near the soil surface （Ta） and soil temperature at 10 cm depth （Tlo） exerted dominant control on the diurnal variations of soil respiration. The time-windows 7：00-9：00 could be used as the optimal measuring time to represent the daily mean soil CO2 effiux at the Cv, Pd, Lc and Pa sites. The daily mean soil CO2 effiux was close to the soil COz effiux from 15：00 to 17：00 and the mean of 2 individual soil CO2 effiux from 15：00 to 19：00 at the As and Sg sites, respectively. During nocturnal hours, negative soil CO2 fluxes （CO2 downwards into the soil） were frequently observed at the As and Sg sites, the magnitude of the negative CO2 fluxes were 0.10-1.55 gmol/（m2.s） and 0.10-0.69 gmol/（m2.s）at the two sites. The results im- plied that alkaline soils could absorb CO2 under natural condition, which might have significant implications to the global carbon budget accounting.展开更多
Pseudomonas aeruginosa is an opportunistic pathogen that contributes to high morbidity and mortality. MexAB-OprM is the main efflux pump among the Resistance-Nodulation-Division family multi-drug effiux systems, which...Pseudomonas aeruginosa is an opportunistic pathogen that contributes to high morbidity and mortality. MexAB-OprM is the main efflux pump among the Resistance-Nodulation-Division family multi-drug effiux systems, which contribute greatly to the multidrug resistance of P. aeruginosa. Effiux pump inhibitors （EPIs） of MexAB-OprM could enhance the activity of the antibiotics effiuxed by MexAB-OprM, and thus they might be useful in the clinic as antibacterial synergistic agents. In this work, a new EPI of MexAB-OprM, KL-0153, was discovered by screening of a small molecular library. Its inhibition of MexAB-OprM was confirmed by assays of synergistic activity and EB accumulation. The activity of KL-0153 was shown to be synergistic with antibiotics effiuxed by MexAB-OprM when they were tested against strains expressing MexAB-OprM, especially so for the strains that express MexAB-OprM at high levels. KL-0153 showed more activity than the positive drug carbonyl cyanide m-chlorophenylhydrazone in the EB accumulation assay. It cannot be neglected that KL-0153 has significant liver and kidney toxicity. However, KL-0153 may be a lead comoound for the research and development of new tvoes of EPIs.展开更多
A single drug chemotherapy fails to eliminate residual cancer cells due to the existence of the multidrug resistance （MDR）. In the present study, we aimed to develop a compound epirubicin plus quinine injection, to ...A single drug chemotherapy fails to eliminate residual cancer cells due to the existence of the multidrug resistance （MDR）. In the present study, we aimed to develop a compound epirubicin plus quinine injection, to characterize the efficacy in treatment of the drug-resistant breast cancer, and to reveal the involved mechanisms. The HPLC-UV methods were developed for quantifications, and the evaluations were performed on the drug-resistant human breast cancer MCF-7/adr cells using a high content screening system. Results demonstrated that the compound epirubicin plus quinine injection was able to effectively block the drug efflux, exhibiting an evidently overall efficacy in treatment of the resistant breast cancer cells by direct killing effect and by apoptosis-inducing effect. In the formulation, quinine played multiple roles in blocking drug efflux and in inducing the apoptosis of the resistant breast cancer cells. The apoptosis signaling pathways were associated with a cascade of reactions by activating Caspase family and by inhibiting Bcl-2 family. In conclusion, the present study preliminarily revealed the efficacy and mechanism of the compound epirubicin plus quinine formulation in treatment of the drug-resistant breast cancer, and offered a potential strategy to overcome drug resistance in cancer treatments.展开更多
It is globally accepted that soil carbon （C） dynamics are at the core of interlinked environmental problems, deteriorating soil quality and changing climate. Its management remains a complex enigma for the scientifi...It is globally accepted that soil carbon （C） dynamics are at the core of interlinked environmental problems, deteriorating soil quality and changing climate. Its management remains a complex enigma for the scientific community due to its intricate relationship with soil nitrogen （N） availability and moisture-temperature interactions. This article reviews the management aspects of soil C dynamics in light of recent advances, particularly in relation to the availability of inorganic N pools and associated microbial processes under changing climate. Globally, drastic alterations in soil C dynamics under changing land use and management practices have been primarily attributed to the variation in soil N availability, resulting in a higher decomposition rate and a considerable decline in soil organic C （SOC） levels due to increased soil CO2 emissions, degraded soil quality, and increased atmospheric CO2 concentrations, leading to climate warming. Predicted climate warming is proposed to enhance SOC decomposition, which may further increase soil N availability, leading to higher soil CO2 effiux. However, a literature survey revealed that soil may also act as a potential C sink, if we could manage soil inorganic N pools and link microbial processes properly. Studies also indicated that the relative, rather than the absolute, availability of inorganic N pools might be of key importance under changing climate, as these N pools are variably affected by moisture-temperature interactions, and they have variable impacts on SOC turnover. Therefore, multi-factorial studies are required to understand how the relative availability of inorganic N pools and associated microbial processes may determine SOC dynamics for improved soil C management.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41501090,41501105)Fundamental Research Funds for Central Universities(No.2412015KJ023)
文摘In order to study the diurnal variation of soil CO2 effiux from temperate meadow steppes in Northeast China, and determine the best time for observation, a field experiment was conducted with a LI-6400 soil CO2 flux system under five typical plant communi- ties （Suaeda glauca （Sg）, Chloris virgata （Cv）, Puecinellia distans （Pd）, Leymus chinensis （Lc） and Phragmites australis （Pa）） and an alkali-spot land （As） at the meadow steppe of western Songnen Plain. The results showed that the diurnal variation of soil CO2 effiux exhibited a single peak curve in the growing season. Diurnal maximum soil respiration （Rs） often appeared between 1 1：00 and 13：00, while the minimum occurred at 21：00-23：00 or before dawn. Air temperature near the soil surface （Ta） and soil temperature at 10 cm depth （Tlo） exerted dominant control on the diurnal variations of soil respiration. The time-windows 7：00-9：00 could be used as the optimal measuring time to represent the daily mean soil CO2 effiux at the Cv, Pd, Lc and Pa sites. The daily mean soil CO2 effiux was close to the soil COz effiux from 15：00 to 17：00 and the mean of 2 individual soil CO2 effiux from 15：00 to 19：00 at the As and Sg sites, respectively. During nocturnal hours, negative soil CO2 fluxes （CO2 downwards into the soil） were frequently observed at the As and Sg sites, the magnitude of the negative CO2 fluxes were 0.10-1.55 gmol/（m2.s） and 0.10-0.69 gmol/（m2.s）at the two sites. The results im- plied that alkaline soils could absorb CO2 under natural condition, which might have significant implications to the global carbon budget accounting.
文摘Pseudomonas aeruginosa is an opportunistic pathogen that contributes to high morbidity and mortality. MexAB-OprM is the main efflux pump among the Resistance-Nodulation-Division family multi-drug effiux systems, which contribute greatly to the multidrug resistance of P. aeruginosa. Effiux pump inhibitors （EPIs） of MexAB-OprM could enhance the activity of the antibiotics effiuxed by MexAB-OprM, and thus they might be useful in the clinic as antibacterial synergistic agents. In this work, a new EPI of MexAB-OprM, KL-0153, was discovered by screening of a small molecular library. Its inhibition of MexAB-OprM was confirmed by assays of synergistic activity and EB accumulation. The activity of KL-0153 was shown to be synergistic with antibiotics effiuxed by MexAB-OprM when they were tested against strains expressing MexAB-OprM, especially so for the strains that express MexAB-OprM at high levels. KL-0153 showed more activity than the positive drug carbonyl cyanide m-chlorophenylhydrazone in the EB accumulation assay. It cannot be neglected that KL-0153 has significant liver and kidney toxicity. However, KL-0153 may be a lead comoound for the research and development of new tvoes of EPIs.
基金National Natural Science Foundation of China(Grant No.81172991 and 81373343)
文摘A single drug chemotherapy fails to eliminate residual cancer cells due to the existence of the multidrug resistance （MDR）. In the present study, we aimed to develop a compound epirubicin plus quinine injection, to characterize the efficacy in treatment of the drug-resistant breast cancer, and to reveal the involved mechanisms. The HPLC-UV methods were developed for quantifications, and the evaluations were performed on the drug-resistant human breast cancer MCF-7/adr cells using a high content screening system. Results demonstrated that the compound epirubicin plus quinine injection was able to effectively block the drug efflux, exhibiting an evidently overall efficacy in treatment of the resistant breast cancer cells by direct killing effect and by apoptosis-inducing effect. In the formulation, quinine played multiple roles in blocking drug efflux and in inducing the apoptosis of the resistant breast cancer cells. The apoptosis signaling pathways were associated with a cascade of reactions by activating Caspase family and by inhibiting Bcl-2 family. In conclusion, the present study preliminarily revealed the efficacy and mechanism of the compound epirubicin plus quinine formulation in treatment of the drug-resistant breast cancer, and offered a potential strategy to overcome drug resistance in cancer treatments.
文摘It is globally accepted that soil carbon （C） dynamics are at the core of interlinked environmental problems, deteriorating soil quality and changing climate. Its management remains a complex enigma for the scientific community due to its intricate relationship with soil nitrogen （N） availability and moisture-temperature interactions. This article reviews the management aspects of soil C dynamics in light of recent advances, particularly in relation to the availability of inorganic N pools and associated microbial processes under changing climate. Globally, drastic alterations in soil C dynamics under changing land use and management practices have been primarily attributed to the variation in soil N availability, resulting in a higher decomposition rate and a considerable decline in soil organic C （SOC） levels due to increased soil CO2 emissions, degraded soil quality, and increased atmospheric CO2 concentrations, leading to climate warming. Predicted climate warming is proposed to enhance SOC decomposition, which may further increase soil N availability, leading to higher soil CO2 effiux. However, a literature survey revealed that soil may also act as a potential C sink, if we could manage soil inorganic N pools and link microbial processes properly. Studies also indicated that the relative, rather than the absolute, availability of inorganic N pools might be of key importance under changing climate, as these N pools are variably affected by moisture-temperature interactions, and they have variable impacts on SOC turnover. Therefore, multi-factorial studies are required to understand how the relative availability of inorganic N pools and associated microbial processes may determine SOC dynamics for improved soil C management.
