Bacterial quorum sensing （QS） has attracted much interests and it is an important process of cell communication. Recently, Bassler et al. studied the phenomena of QS regulated by small RNAs and the experimental data...Bacterial quorum sensing （QS） has attracted much interests and it is an important process of cell communication. Recently, Bassler et al. studied the phenomena of QS regulated by small RNAs and the experimental data showed that smafl RNAs played important role in the QS of Vibrio harveyi and it can permit the fine-tuning of gene regulation and mmntenance of homeostasis. According to Michaelis-Menten kinetics and mass action law in this paper, we construct a mathematical model to investigate the mechanism induced QS by coexist of small RNA and signal molecular （AI） and show that there are periodic oscillation when the time delay and Hill coefficient exceed a critical value and the periodic oscillation produces the change of concentration and induces QS. These results are fit to the experimental results. In the meanwhile, we also get some theoretical value of Hopf Bifurcation on time deday. In addition, we also find this network is robust against noise.展开更多
Plants exhibit an astonishing ability to regulate organ regeneration upon wounding.Excision of leaf explants promotes the biosynthesis of indole-3-acetic acid(IAA),which is polar-transported to excised regions,where c...Plants exhibit an astonishing ability to regulate organ regeneration upon wounding.Excision of leaf explants promotes the biosynthesis of indole-3-acetic acid(IAA),which is polar-transported to excised regions,where cell fate transition leads to root founder cell specification to induce de novo root regeneration.The regeneration capacity of plants has been utilized to develop in vitro tissue culture technologies.Here,we report that IAA accumulation near the wounded site of leaf explants is essential for callus formation on 2,4-dichlorophenoxyacetic acid(2,4-D)-rich callus-inducing medium(CIM).Notably,a high concentration of 2,4-D does not compensate for the action of IAA because of its limited efflux;rather,it lowers IAA biosynthesis via a negative feedback mechanism at an early stage of in vitro tissue culture,delaying callus initiation.The auxin negative feedback loop in CIM-cultured leaf explants is mediated by an auxin-inducible APETALA2 transcription factor,ENHANCER OF SHOOT REGENERATION 2(ESR2),along with its interacting partner HISTONE DEACETYLASE 6(HDA6).The ESR2–HDA6 complex binds directly to,and removes the H3ac mark from,the YUCCA1(YUC1),YUC7,and YUC9 loci,consequently repressing auxin biosynthesis and inhibiting cell fate transition on 2,4-D-rich CIM.These findings indicate that negative feedback regulation of auxin biosynthesis by ESR2 and HDA6 interferes with proper cell fate transition and callus initiation.展开更多
The stability problem arising from the DC-link voltage outer loop and current inner loop control in weak-grid-tied interlinking voltage-source converters(VSC)system has been extensively investigated.However,the differ...The stability problem arising from the DC-link voltage outer loop and current inner loop control in weak-grid-tied interlinking voltage-source converters(VSC)system has been extensively investigated.However,the different impacts on system stability caused by these controller parameters have not been well solved.A three-port hybrid AC/DC admittance-based model for VSC taking into account AC-and DC-side dynamics is developed for revealing the mechanism intuitively on the formation of the positive and negative feedback effects in the DC-link voltage control loop.Subsequently,the stability characteristics of the voltage outer loop and current inner loop controller parameters on VSC are analyzed.Compared to adjusting the voltage outer loop controller parameters which has significant effort on the dynamic regulation characteristics,it is more sensitive on system stability by the parameter change of the current inner loop controller.Theoretical results,along with experimental verification,are provided to validate the analysis.展开更多
Brassinosteroids are known regulators of meristem activity in Arabidopsis,with low levels being sufficient for normal growth within the proliferating cells of the meristem.Brassinosteroid biosynthesis enzymes are tran...Brassinosteroids are known regulators of meristem activity in Arabidopsis,with low levels being sufficient for normal growth within the proliferating cells of the meristem.Brassinosteroid biosynthesis enzymes are transcriptionally downregulated in response to increased brassinosteroid signaling activity,forming a negative feedback loop to modulate their own expression(Ackerman-Lavert et al.,2021;Vukašinovićet al.,2021).展开更多
Although both protein arginine methylation(PRMT)and jasmonate(JA)signaling are crucial for regulating plant development,the relationship between these processes in the control of spikelet development remains unclear.I...Although both protein arginine methylation(PRMT)and jasmonate(JA)signaling are crucial for regulating plant development,the relationship between these processes in the control of spikelet development remains unclear.In this study,we used the CRISPR/Cas9 technology to generate two OsPRMT6a loss-of-function mutants that exhibit various abnormal spikelet structures.Interestingly,we found that OsPRMT6a can methylate arginine residues in JA signal repressors OsJAZ1 and OsJAZ7.We showed that arginine methylation of OsJAZ1 enhances the binding affinity of OsJAZ1 with the JA receptors OsCOI1a and OsCOI1b in the presence of JAs,thereby promoting the ubiquitination of OsJAZ1 by the SCF^(OsCOI1a/OsCOI1b) complex and degradation via the 26S proteasome.This process ultimately releases OsMYC2,a core transcriptional regulator in the JA signaling pathway,to activate or repress JA-responsive genes,thereby maintaining normal plant(spikelet)development.However,in the osprmt6a-1 mutant,reduced arginine methylation of OsJAZ1 impaires the interaction between OsJAZ1 and OsCOI1a/OsCOI1b in the presence of JAs.As a result,OsJAZ1 proteins become more stable,repressing JA responses,thus causing the formation of abnormal spikelet structures.Moreover,we discovered that JA signaling reduces the OsPRMT6a mRNA level in an OsMYC2-dependent manner,thereby establishing a negative feedback loop to balance JA signaling.We further found that OsPRMT6a-mediated arginine methylation of OsJAZ1 likely serves as a switch to tune JA signaling to maintain normal spikelet development under harsh environmental conditions such as high temperatures.Collectively,our study establishes a direct molecular link between arginine methylation and JA signaling in rice.展开更多
apamvcin was first isolated from a strain of Sreptomyces hygroscopicus in the early 1970s froma soil sample taken on Easter Island. Because the antiproliferative effects of rapamycin on yeast cell, as well as B and T ...apamvcin was first isolated from a strain of Sreptomyces hygroscopicus in the early 1970s froma soil sample taken on Easter Island. Because the antiproliferative effects of rapamycin on yeast cell, as well as B and T lymphocytes, it was first identified as an antimicrobial agent with potent immunosuppressive activity and has been used in antirejection therapy.展开更多
This paper presents post-layout simulated results of an analog baseband chain for mobile and multimedia applications in a 0.13-μm SiGe BiCMOS process.A programmable 7th-order Chebyshev low pass filter with a calibrat...This paper presents post-layout simulated results of an analog baseband chain for mobile and multimedia applications in a 0.13-μm SiGe BiCMOS process.A programmable 7th-order Chebyshev low pass filter with a calibration circuit is used in the analog baseband chain,and the programmable bandwidth is 1.8/2.5/3/3.5/4 MHz with an attenuation of 26/62 dB at offsets of 1.25/4 MHz.The baseband programmable gain amplifier can achieve a linear 40-dB gain range with 0.5-dB steps.Design trade-offs are carefully considered in designing the baseband circuit,and an automatic calibration circuit is used to achieve the bandwidth accuracy of 2%.A DC offset cancellation loop is also introduced to remove the offset from the layout and self-mixing,and the remaining offset voltage is only 1.87 mV.Implemented in a 0.13-μm SiGe technology with a 0.6-mm2 die size,this baseband achieves IIP3 of 23.16 dBm and dissipates 22.4 mA under a 2.5-V supply.展开更多
基金Supported by National Natural Science Foundation of China under Grant Nos. 10802043 and 10832006, Program for Science ＆ Technology Innovation Talents in Universities of Henan under Grant No. 2009HASTIT033 and Key Disciplines of Shanghai municipality （$30104）
文摘Bacterial quorum sensing （QS） has attracted much interests and it is an important process of cell communication. Recently, Bassler et al. studied the phenomena of QS regulated by small RNAs and the experimental data showed that smafl RNAs played important role in the QS of Vibrio harveyi and it can permit the fine-tuning of gene regulation and mmntenance of homeostasis. According to Michaelis-Menten kinetics and mass action law in this paper, we construct a mathematical model to investigate the mechanism induced QS by coexist of small RNA and signal molecular （AI） and show that there are periodic oscillation when the time delay and Hill coefficient exceed a critical value and the periodic oscillation produces the change of concentration and induces QS. These results are fit to the experimental results. In the meanwhile, we also get some theoretical value of Hopf Bifurcation on time deday. In addition, we also find this network is robust against noise.
基金supported by the Basic Science Research(NRF-2022R1A 2B5B02001266)Basic Research Laboratory(NRF-2022R1A4A 3024451)programs funded by the National Research Foundation of Korea(South Korea)the New Breeding Technologies Development Program(RS-2024-00322275)of the Rural Development Administration(South Korea).
文摘Plants exhibit an astonishing ability to regulate organ regeneration upon wounding.Excision of leaf explants promotes the biosynthesis of indole-3-acetic acid(IAA),which is polar-transported to excised regions,where cell fate transition leads to root founder cell specification to induce de novo root regeneration.The regeneration capacity of plants has been utilized to develop in vitro tissue culture technologies.Here,we report that IAA accumulation near the wounded site of leaf explants is essential for callus formation on 2,4-dichlorophenoxyacetic acid(2,4-D)-rich callus-inducing medium(CIM).Notably,a high concentration of 2,4-D does not compensate for the action of IAA because of its limited efflux;rather,it lowers IAA biosynthesis via a negative feedback mechanism at an early stage of in vitro tissue culture,delaying callus initiation.The auxin negative feedback loop in CIM-cultured leaf explants is mediated by an auxin-inducible APETALA2 transcription factor,ENHANCER OF SHOOT REGENERATION 2(ESR2),along with its interacting partner HISTONE DEACETYLASE 6(HDA6).The ESR2–HDA6 complex binds directly to,and removes the H3ac mark from,the YUCCA1(YUC1),YUC7,and YUC9 loci,consequently repressing auxin biosynthesis and inhibiting cell fate transition on 2,4-D-rich CIM.These findings indicate that negative feedback regulation of auxin biosynthesis by ESR2 and HDA6 interferes with proper cell fate transition and callus initiation.
基金supported by the National Natural Science Foundation of China(No.52177184)the Shanghai Municipality on Natural Science Fund(No.21ZR1425300).
文摘The stability problem arising from the DC-link voltage outer loop and current inner loop control in weak-grid-tied interlinking voltage-source converters(VSC)system has been extensively investigated.However,the different impacts on system stability caused by these controller parameters have not been well solved.A three-port hybrid AC/DC admittance-based model for VSC taking into account AC-and DC-side dynamics is developed for revealing the mechanism intuitively on the formation of the positive and negative feedback effects in the DC-link voltage control loop.Subsequently,the stability characteristics of the voltage outer loop and current inner loop controller parameters on VSC are analyzed.Compared to adjusting the voltage outer loop controller parameters which has significant effort on the dynamic regulation characteristics,it is more sensitive on system stability by the parameter change of the current inner loop controller.Theoretical results,along with experimental verification,are provided to validate the analysis.
文摘Brassinosteroids are known regulators of meristem activity in Arabidopsis,with low levels being sufficient for normal growth within the proliferating cells of the meristem.Brassinosteroid biosynthesis enzymes are transcriptionally downregulated in response to increased brassinosteroid signaling activity,forming a negative feedback loop to modulate their own expression(Ackerman-Lavert et al.,2021;Vukašinovićet al.,2021).
基金We thank Prof.Qiang Cai(College of Life Sciences,Wuhan University)and Prof.Zheng Yuan(School of Life Sciences and Biotechnology,Shanghai Jiao Tong University)for providing morphology data for the eg1-1 and eg2-1D mutants.This work was supported by grants from the National Key R&D Program of China(2022YFD1200100)STI2030-Major Projects(2023ZD0406802)the National Natural Science Foundation of China(no.92035301 and no.31771765).
文摘Although both protein arginine methylation(PRMT)and jasmonate(JA)signaling are crucial for regulating plant development,the relationship between these processes in the control of spikelet development remains unclear.In this study,we used the CRISPR/Cas9 technology to generate two OsPRMT6a loss-of-function mutants that exhibit various abnormal spikelet structures.Interestingly,we found that OsPRMT6a can methylate arginine residues in JA signal repressors OsJAZ1 and OsJAZ7.We showed that arginine methylation of OsJAZ1 enhances the binding affinity of OsJAZ1 with the JA receptors OsCOI1a and OsCOI1b in the presence of JAs,thereby promoting the ubiquitination of OsJAZ1 by the SCF^(OsCOI1a/OsCOI1b) complex and degradation via the 26S proteasome.This process ultimately releases OsMYC2,a core transcriptional regulator in the JA signaling pathway,to activate or repress JA-responsive genes,thereby maintaining normal plant(spikelet)development.However,in the osprmt6a-1 mutant,reduced arginine methylation of OsJAZ1 impaires the interaction between OsJAZ1 and OsCOI1a/OsCOI1b in the presence of JAs.As a result,OsJAZ1 proteins become more stable,repressing JA responses,thus causing the formation of abnormal spikelet structures.Moreover,we discovered that JA signaling reduces the OsPRMT6a mRNA level in an OsMYC2-dependent manner,thereby establishing a negative feedback loop to balance JA signaling.We further found that OsPRMT6a-mediated arginine methylation of OsJAZ1 likely serves as a switch to tune JA signaling to maintain normal spikelet development under harsh environmental conditions such as high temperatures.Collectively,our study establishes a direct molecular link between arginine methylation and JA signaling in rice.
基金This work was supported by grants from National Natural Science Foundation of China （No. 30971312） and the Key Project of Beijing Municipal Education Commission Sci-Tech Development Program （No. KZ201110025028）.
文摘apamvcin was first isolated from a strain of Sreptomyces hygroscopicus in the early 1970s froma soil sample taken on Easter Island. Because the antiproliferative effects of rapamycin on yeast cell, as well as B and T lymphocytes, it was first identified as an antimicrobial agent with potent immunosuppressive activity and has been used in antirejection therapy.
基金Project supported by the Provincial and Ministerial Industry-Academia Cooperation Project of China(No.2009A090100019)
文摘This paper presents post-layout simulated results of an analog baseband chain for mobile and multimedia applications in a 0.13-μm SiGe BiCMOS process.A programmable 7th-order Chebyshev low pass filter with a calibration circuit is used in the analog baseband chain,and the programmable bandwidth is 1.8/2.5/3/3.5/4 MHz with an attenuation of 26/62 dB at offsets of 1.25/4 MHz.The baseband programmable gain amplifier can achieve a linear 40-dB gain range with 0.5-dB steps.Design trade-offs are carefully considered in designing the baseband circuit,and an automatic calibration circuit is used to achieve the bandwidth accuracy of 2%.A DC offset cancellation loop is also introduced to remove the offset from the layout and self-mixing,and the remaining offset voltage is only 1.87 mV.Implemented in a 0.13-μm SiGe technology with a 0.6-mm2 die size,this baseband achieves IIP3 of 23.16 dBm and dissipates 22.4 mA under a 2.5-V supply.
