Magnetotactic bacteria can orientate in the Earth’s magnetic field to search for their preferred microoxic environments,which is achieved by their unique organelles,the magnetosomes.Magnetosomes contain nanometer-siz...Magnetotactic bacteria can orientate in the Earth’s magnetic field to search for their preferred microoxic environments,which is achieved by their unique organelles,the magnetosomes.Magnetosomes contain nanometer-sized crystal particles of magnetic iron minerals,which are only synthesized in lowoxygen environments.Although the mechanism of aerobic repression for magnetosome biomineralization has not yet fully understood,a series of studies have verified that redox modulation is pivotal for magnetosome formation.In this review,these advances in redox modulation for magnetosome biosynthesis are highlighted,mainly including respiration pathway enzymes,specific magnetosome-associated redox proteins,and oxygen-or nitrate-sensing regulators.Furthermore,their relationship during magnetosome biomineralization is discussed to give insight into redox control and biomineralization and inspire potential solutions for the application of respiration pathways to improve the yields of magnetosome.展开更多
A functional relationship between monothiol glutaredoxins and BolAs has been unraveled by genomic analyses and in several high-throughput studies. Phylogenetic analyses coupled to transient expression of green fluo- r...A functional relationship between monothiol glutaredoxins and BolAs has been unraveled by genomic analyses and in several high-throughput studies. Phylogenetic analyses coupled to transient expression of green fluo- rescent protein （GFP） fusions indicated that, in addition to the sulfurtransferase SufE1, which contains a C-terminal BolA domain, three BolA isoforms exist in Arabidopsis thaliana, BolA1 being plastidial, BolA2 nucleo-cytoplasmic, and BolA4 dual-targeted to mitochondria and plastids. Binary yeast two-hybrid experiments demonstrated that all BolAs and SufE 1, via its BolA domain, can interact with all monothiol glutaredoxins. Most interactions between protein couples of the same subcellular compartment have been confirmed by bimolecular fluorescence complementation. In vitro experiments indicated that monothiol glutaredoxins could regulate the redox state of BolA2 and SufE1, both proteins possessing a single conserved reactive cysteine. Indeed, a glutathionylated form of SufE1 lost its capacity to activate the cysteine desuifurase, Nfs2, but it is reactivated by plastidial glutaredoxins. Besides, a monomeric glutathionyiated form and a dimeric disulfide-bridged form of BolA2 can be preferentially reduced by the nucleo-cytoplasmic GrxS17. These results indicate that the glutaredoxin-BolA interaction occurs in several subcellular compartments and suggest that a redox regulation mechanism, disconnected from their capacity to form iron-sulfur cluster-bridged heterodimers, may be physiologically relevant for BolA2 and SufE1.展开更多
An inclusion-interaction assembly strategy was used to construct novel pH/redox responsive core-shell micelles with hydrophobic drug as the core and hydrophilic polymer as the shell. At first, a dimer of hydrophobic d...An inclusion-interaction assembly strategy was used to construct novel pH/redox responsive core-shell micelles with hydrophobic drug as the core and hydrophilic polymer as the shell. At first, a dimer of hydrophobic drug 6-mercaptopurine and a hydrophilic β-CD grafted carboxymethyl chitosan were synthesized. Then, a novel amphiphilic inclusion complex was prepared with the dimer being partially embedded into the cavity of β-CD moiety. It self-assembled into pH/redox responsive core-shell micelles in distilled water. TEM confirmed that the micelles possessed a spherical core-shell configuration with a mean size of about 160 nm. DLS showed that the micelles were stable in aqueous solution. Their particle diameters altered with pH values as well as glutathione (GSH) concentrations and respectively attained a maximum value at pH 6.0 and 20 mM GSH. Release profiles of 6-mercaptopurine showed a low release rate (about 27 wt% after 48 h) in pH 7.4 medium with 10 μM GSH, and a marked increase (over 88 wt% after 48 h) in pH 5.0 medium with 20 mM GSH. In vitro cytotoxicity test showed that the micelles had a dose-dependent toxicity for HeLa cells, indicating a great potential for controlled release of 6-mercaptopurine in tumor cells.展开更多
为了提高全钒液流电池(Vanadium redox battery,VRB)储能系统功率控制的快速性,文中提出一种分段量化小脑模型神经网络(piecewise cerebella model articulation controller,PCMAC)与比例积分微分控制(proportion integral differential...为了提高全钒液流电池(Vanadium redox battery,VRB)储能系统功率控制的快速性,文中提出一种分段量化小脑模型神经网络(piecewise cerebella model articulation controller,PCMAC)与比例积分微分控制(proportion integral differential,PID)相结合的复合控制策略(PCMAC⁃PID),由PCMAC实现前馈控制,PID实现反馈控制。建立了VRB储能系统的数学模型,给出了复合控制器的结构及具体算法,最后通过仿真验证了复合控制策略的有效性。仿真结果表明,与PID算法相比,复合控制策略能更好地提高控制系统的响应速度且具有一定的鲁棒性。展开更多
Load frequency control plays a vital role in power system operation and control. LFC regulates the frequency of larger interconnected power systems and keeps the net interchange of power between the pool members at pr...Load frequency control plays a vital role in power system operation and control. LFC regulates the frequency of larger interconnected power systems and keeps the net interchange of power between the pool members at predetermined values for the corresponding changes in load demand. In this paper, the two-area, hydrothermal deregulated power system is considered with Redox Flow Batteries (RFB) in both the areas. RFB is an energy storage device, which converts electrical energy into chemical energy, that is used to meet the sudden requirement of real power load and hence very effective in reducing the peak shoots. With conventional proportional-integral (PI) controller, it is difficult to get the optimum solution. Hence, intelligent techniques are used to tune the PI controller of the LFC to improve the dynamic response. In the family of intelligent techniques, a recent nature inspired algorithm called the Flower Pollination Algorithm (FPA) gives the global minima solution. The optimal value of the controller is determined by minimizing the ISE. The results show that the proposed FPA tuned PI controller improves the dynamic response of the deregulated system faster than the PI controller for different cases. The simulation is implemented in MATLAB environment.展开更多
Pyridine nucleotides, ascorbate and glutathione are major redox metabolites in plant cells, with specific roles in cellular redox homeostasis and the regulation of the cell cycle. However, the regulation of these meta...Pyridine nucleotides, ascorbate and glutathione are major redox metabolites in plant cells, with specific roles in cellular redox homeostasis and the regulation of the cell cycle. However, the regulation of these metabolite pools during exponential growth and their precise functions in the cell cycle remain to be characterized. The present analysis of the abundance of ascorbate, glutathione, and pyridine nucleotides during exponential growth of Arabidopsis cells in culture provides evidence for the differential regulation of each of these redox pools. Ascorbate was most abundant early in the growth cycle, but glutathione was low at this point. The cellular ascorbate to dehydroascorbate and reduced glutathione （GSH） to glutathione disulphide ratios were high and constant but the pyridine nucleotide pools were largely oxidized over the period of exponential growth and only became more reduced once growth had ceased. The glutathione pool increased in parallel with poly （ADP-ribose） polymerase （PARP） activities and with increases in the abundance of PARP1 and PARP2 mRNAs at a time of high cell cycle activity as indicated by transcriptome information. Marked changes in the intracellular partitioning of GSH between the cytoplasm and nucleus were observed. Extension of the exponential growth phase by dilution or changing the media led to increases in the glutathione and nicotinamide adenine dinucleotide, oxidized form （NAD）-plus-nicotinamide adenine dinucleotide, reduced form （NADH） pools and to higher NAD/NADH ratios but the nicotinamide adenine dinucleotide phosphate, oxidized form （NADP）-plus-nicotinamide adenine dinucleotide phosphate, reduced form （NADPH） pool sizes, and NAPD/NADPH ratios were much less affected. The ascorbate, glutathione, and pyridine nucleotide pools and PARP activity decreased before the exponential growth phase ended. We conclude that there are marked changes in intracellular redox state during the growth cycle but that redox homeostasis is maintained by interplay of the major redox pyridine nucleotides, glutathione, and ascorbate pools. The correlation between PARP expression and activity and GSH accumulation and the finding that GSH can be recruited to the nucleus suggest a relationship between redox regulation and nuclear enzyme activity.展开更多
基金Supported by the National Natural Science Foundation of China(No.41706165)the Fundamental Research Funds of Shandong University(No.2019HW022)。
文摘Magnetotactic bacteria can orientate in the Earth’s magnetic field to search for their preferred microoxic environments,which is achieved by their unique organelles,the magnetosomes.Magnetosomes contain nanometer-sized crystal particles of magnetic iron minerals,which are only synthesized in lowoxygen environments.Although the mechanism of aerobic repression for magnetosome biomineralization has not yet fully understood,a series of studies have verified that redox modulation is pivotal for magnetosome formation.In this review,these advances in redox modulation for magnetosome biosynthesis are highlighted,mainly including respiration pathway enzymes,specific magnetosome-associated redox proteins,and oxygen-or nitrate-sensing regulators.Furthermore,their relationship during magnetosome biomineralization is discussed to give insight into redox control and biomineralization and inspire potential solutions for the application of respiration pathways to improve the yields of magnetosome.
文摘A functional relationship between monothiol glutaredoxins and BolAs has been unraveled by genomic analyses and in several high-throughput studies. Phylogenetic analyses coupled to transient expression of green fluo- rescent protein （GFP） fusions indicated that, in addition to the sulfurtransferase SufE1, which contains a C-terminal BolA domain, three BolA isoforms exist in Arabidopsis thaliana, BolA1 being plastidial, BolA2 nucleo-cytoplasmic, and BolA4 dual-targeted to mitochondria and plastids. Binary yeast two-hybrid experiments demonstrated that all BolAs and SufE 1, via its BolA domain, can interact with all monothiol glutaredoxins. Most interactions between protein couples of the same subcellular compartment have been confirmed by bimolecular fluorescence complementation. In vitro experiments indicated that monothiol glutaredoxins could regulate the redox state of BolA2 and SufE1, both proteins possessing a single conserved reactive cysteine. Indeed, a glutathionylated form of SufE1 lost its capacity to activate the cysteine desuifurase, Nfs2, but it is reactivated by plastidial glutaredoxins. Besides, a monomeric glutathionyiated form and a dimeric disulfide-bridged form of BolA2 can be preferentially reduced by the nucleo-cytoplasmic GrxS17. These results indicate that the glutaredoxin-BolA interaction occurs in several subcellular compartments and suggest that a redox regulation mechanism, disconnected from their capacity to form iron-sulfur cluster-bridged heterodimers, may be physiologically relevant for BolA2 and SufE1.
文摘An inclusion-interaction assembly strategy was used to construct novel pH/redox responsive core-shell micelles with hydrophobic drug as the core and hydrophilic polymer as the shell. At first, a dimer of hydrophobic drug 6-mercaptopurine and a hydrophilic β-CD grafted carboxymethyl chitosan were synthesized. Then, a novel amphiphilic inclusion complex was prepared with the dimer being partially embedded into the cavity of β-CD moiety. It self-assembled into pH/redox responsive core-shell micelles in distilled water. TEM confirmed that the micelles possessed a spherical core-shell configuration with a mean size of about 160 nm. DLS showed that the micelles were stable in aqueous solution. Their particle diameters altered with pH values as well as glutathione (GSH) concentrations and respectively attained a maximum value at pH 6.0 and 20 mM GSH. Release profiles of 6-mercaptopurine showed a low release rate (about 27 wt% after 48 h) in pH 7.4 medium with 10 μM GSH, and a marked increase (over 88 wt% after 48 h) in pH 5.0 medium with 20 mM GSH. In vitro cytotoxicity test showed that the micelles had a dose-dependent toxicity for HeLa cells, indicating a great potential for controlled release of 6-mercaptopurine in tumor cells.
文摘为了提高全钒液流电池(Vanadium redox battery,VRB)储能系统功率控制的快速性,文中提出一种分段量化小脑模型神经网络(piecewise cerebella model articulation controller,PCMAC)与比例积分微分控制(proportion integral differential,PID)相结合的复合控制策略(PCMAC⁃PID),由PCMAC实现前馈控制,PID实现反馈控制。建立了VRB储能系统的数学模型,给出了复合控制器的结构及具体算法,最后通过仿真验证了复合控制策略的有效性。仿真结果表明,与PID算法相比,复合控制策略能更好地提高控制系统的响应速度且具有一定的鲁棒性。
文摘Load frequency control plays a vital role in power system operation and control. LFC regulates the frequency of larger interconnected power systems and keeps the net interchange of power between the pool members at predetermined values for the corresponding changes in load demand. In this paper, the two-area, hydrothermal deregulated power system is considered with Redox Flow Batteries (RFB) in both the areas. RFB is an energy storage device, which converts electrical energy into chemical energy, that is used to meet the sudden requirement of real power load and hence very effective in reducing the peak shoots. With conventional proportional-integral (PI) controller, it is difficult to get the optimum solution. Hence, intelligent techniques are used to tune the PI controller of the LFC to improve the dynamic response. In the family of intelligent techniques, a recent nature inspired algorithm called the Flower Pollination Algorithm (FPA) gives the global minima solution. The optimal value of the controller is determined by minimizing the ISE. The results show that the proposed FPA tuned PI controller improves the dynamic response of the deregulated system faster than the PI controller for different cases. The simulation is implemented in MATLAB environment.
文摘Pyridine nucleotides, ascorbate and glutathione are major redox metabolites in plant cells, with specific roles in cellular redox homeostasis and the regulation of the cell cycle. However, the regulation of these metabolite pools during exponential growth and their precise functions in the cell cycle remain to be characterized. The present analysis of the abundance of ascorbate, glutathione, and pyridine nucleotides during exponential growth of Arabidopsis cells in culture provides evidence for the differential regulation of each of these redox pools. Ascorbate was most abundant early in the growth cycle, but glutathione was low at this point. The cellular ascorbate to dehydroascorbate and reduced glutathione （GSH） to glutathione disulphide ratios were high and constant but the pyridine nucleotide pools were largely oxidized over the period of exponential growth and only became more reduced once growth had ceased. The glutathione pool increased in parallel with poly （ADP-ribose） polymerase （PARP） activities and with increases in the abundance of PARP1 and PARP2 mRNAs at a time of high cell cycle activity as indicated by transcriptome information. Marked changes in the intracellular partitioning of GSH between the cytoplasm and nucleus were observed. Extension of the exponential growth phase by dilution or changing the media led to increases in the glutathione and nicotinamide adenine dinucleotide, oxidized form （NAD）-plus-nicotinamide adenine dinucleotide, reduced form （NADH） pools and to higher NAD/NADH ratios but the nicotinamide adenine dinucleotide phosphate, oxidized form （NADP）-plus-nicotinamide adenine dinucleotide phosphate, reduced form （NADPH） pool sizes, and NAPD/NADPH ratios were much less affected. The ascorbate, glutathione, and pyridine nucleotide pools and PARP activity decreased before the exponential growth phase ended. We conclude that there are marked changes in intracellular redox state during the growth cycle but that redox homeostasis is maintained by interplay of the major redox pyridine nucleotides, glutathione, and ascorbate pools. The correlation between PARP expression and activity and GSH accumulation and the finding that GSH can be recruited to the nucleus suggest a relationship between redox regulation and nuclear enzyme activity.
