The Ib subgroup of the bHLH gene family in Arabidopsis contains four members （AtbHLH38, AtbHLH39, AtbHLHIO0, and AtbHLH101）. AtbHLH38 and AtbHLH39 were previously confirmed to interact with FER-like iron deft-ciency...The Ib subgroup of the bHLH gene family in Arabidopsis contains four members （AtbHLH38, AtbHLH39, AtbHLHIO0, and AtbHLH101）. AtbHLH38 and AtbHLH39 were previously confirmed to interact with FER-like iron deft-ciency induced transcription factor （FIT）, directly functioning in activation of the expression of ferric-chelate reductase FRO2 and high-affinity ferrous iron transporter IRT1. In this work, we characterized the functions of AtbHLH100 and AtbHLH101 in the regulation of the iron-deficiency responses and uptake. Yeast two-hybrid analysis and bimolecular fluorescence complementation assay demonstrated that both AtbHLH100 and AtbHLH101 could interact with FIT. Dual expression of either AtbHLH100 or AtbHLH101 with FIT in yeast cells activated the GUS expression driven by promoters of FRO2 and IRT1. The plants overexpressing FIT together with AtbHLHI01 showed constitutive expression of FRO2 and IRT1 in roots, and accumulated more iron in shoots. Further, the single, double, and triple knockout mutants of AtbHLH38, AtbHLH39, AtbHLH100, and AtbHLH101 were generated and characterized. The FRO2 and IRT1 expression in roots and the iron content in shoots were more drastically decreased in the triple knockout mutant of AtbHLH39, AtbHLH100, and AtbHLH101 than that of the other available double and triple mutants of the four genes. Comparison of the physiological responses as well as the expression of FRO2 and IRT1 in the multiple knockout mutants under iron deficiency revealed that AtbHLH100, AtbHLH38, AtbHLH101, and AtbHLH39 played the gradually increased important role in the iron-deficiency responses and uptake. Taken all together, we conclude that the four Ib subgroup bHLH proteins are required and possess redundant functions with differential significance for activation of iron-deficiency responses and uptake in Arabidopsis.展开更多
利用双曲正切函数对凸组合最小均方(Convex Combination of Least Mean Square,CLMS)算法进行了改进,提出了Th-VSCLMS(Tanh Variable Step Convex Combined Least Mean Square)算法。理论分析表明:改进算法的性能优于普通的变步长算法...利用双曲正切函数对凸组合最小均方(Convex Combination of Least Mean Square,CLMS)算法进行了改进,提出了Th-VSCLMS(Tanh Variable Step Convex Combined Least Mean Square)算法。理论分析表明:改进算法的性能优于普通的变步长算法。在不同信噪比下对VSLMS(Variable Step Least Mean Square)、CLMS、Th-VSCLMS算法进行了仿真对比分析,结果表明:Th-VSCLMS算法的收敛性、稳态性、抗扰动性、低信噪比的滤波效果、计算量均得到较好的改善,且其凸组合滤波结构优于单一滤波结构。展开更多
文摘The Ib subgroup of the bHLH gene family in Arabidopsis contains four members （AtbHLH38, AtbHLH39, AtbHLHIO0, and AtbHLH101）. AtbHLH38 and AtbHLH39 were previously confirmed to interact with FER-like iron deft-ciency induced transcription factor （FIT）, directly functioning in activation of the expression of ferric-chelate reductase FRO2 and high-affinity ferrous iron transporter IRT1. In this work, we characterized the functions of AtbHLH100 and AtbHLH101 in the regulation of the iron-deficiency responses and uptake. Yeast two-hybrid analysis and bimolecular fluorescence complementation assay demonstrated that both AtbHLH100 and AtbHLH101 could interact with FIT. Dual expression of either AtbHLH100 or AtbHLH101 with FIT in yeast cells activated the GUS expression driven by promoters of FRO2 and IRT1. The plants overexpressing FIT together with AtbHLHI01 showed constitutive expression of FRO2 and IRT1 in roots, and accumulated more iron in shoots. Further, the single, double, and triple knockout mutants of AtbHLH38, AtbHLH39, AtbHLH100, and AtbHLH101 were generated and characterized. The FRO2 and IRT1 expression in roots and the iron content in shoots were more drastically decreased in the triple knockout mutant of AtbHLH39, AtbHLH100, and AtbHLH101 than that of the other available double and triple mutants of the four genes. Comparison of the physiological responses as well as the expression of FRO2 and IRT1 in the multiple knockout mutants under iron deficiency revealed that AtbHLH100, AtbHLH38, AtbHLH101, and AtbHLH39 played the gradually increased important role in the iron-deficiency responses and uptake. Taken all together, we conclude that the four Ib subgroup bHLH proteins are required and possess redundant functions with differential significance for activation of iron-deficiency responses and uptake in Arabidopsis.
文摘利用双曲正切函数对凸组合最小均方(Convex Combination of Least Mean Square,CLMS)算法进行了改进,提出了Th-VSCLMS(Tanh Variable Step Convex Combined Least Mean Square)算法。理论分析表明:改进算法的性能优于普通的变步长算法。在不同信噪比下对VSLMS(Variable Step Least Mean Square)、CLMS、Th-VSCLMS算法进行了仿真对比分析,结果表明:Th-VSCLMS算法的收敛性、稳态性、抗扰动性、低信噪比的滤波效果、计算量均得到较好的改善,且其凸组合滤波结构优于单一滤波结构。
