目的:收集关于神经示踪技术应用于实验针灸研究的相关文献,总结分析其在腧穴、经脉、脏腑等方面的应用状况。方法:本研究以"示踪技术OR神经示踪技术OR示踪剂OR神经示踪剂OR示踪OR神经示踪"和"针灸OR针刺OR电针OR耳针OR眼...目的:收集关于神经示踪技术应用于实验针灸研究的相关文献,总结分析其在腧穴、经脉、脏腑等方面的应用状况。方法:本研究以"示踪技术OR神经示踪技术OR示踪剂OR神经示踪剂OR示踪OR神经示踪"和"针灸OR针刺OR电针OR耳针OR眼针OR经脉OR穴区OR腧穴OR穴位注射"为检索词检索中国知网(CNKI,1979-2017)、万方数据知识平台(Wan-Fang Data,1990-2017)、维普资讯中文期刊服务平台(VIP Date,1989-2017);以"neural tracing technique OR neuroanatomical tracing OR neuronal tracers"and"acupuncture OR electroacupuncture OR auricular acupuncture OR eye acupuncture OR meridians OR acupuncture points OR acupoint injection"为关键词检索英文数据库PubMed(1997-2017)。结果:共收录与本研究相关的文献94篇。其中使用最多的神经示踪剂是辣根过氧化物酶和霍乱毒素亚单位B,采用的实验动物有大鼠、家兔、猫和猴等,示踪剂的注射部位以腧穴居多。示踪剂注射后动物的存活时间从1 d到12周不等,所标记的神经成分包括感觉、运动和自主神经系统相关的神经元及其神经纤维。这些文献主要揭示了腧穴和脏腑的神经支配具有区域性和节段性特征,二者之间存在密切的神经解剖学联系,而其相关的神经元和神经纤维的化学特征(通过免疫荧光组织化学染色显示)与针灸作用途径密切相关。结论:应用神经示踪技术可以从神经通路/环路及其相关化学性质等不同角度更加深入地了解针灸的作用途径,这也为该项技术在将来的实验针灸研究中发挥更大的作用奠定了基础。展开更多
The Arabidopsis thaliana RPD3-type histone deacetylases have been known to form conserved SIN3-type histone deacetylase complexes,but whether they form other types of complexes is unknown.Here,we perform affinity puri...The Arabidopsis thaliana RPD3-type histone deacetylases have been known to form conserved SIN3-type histone deacetylase complexes,but whether they form other types of complexes is unknown.Here,we perform affinity purification followed by mass spectrometry and demonstrate that the Arabidopsis RPD3-type histone deacetylases HDA6 and HDA19 interact with several previously uncharacterized proteins,thereby forming three types of plant-specific histone deacetylase complexes,which we named SANT,ESANT,and ARID.RNA-seq indicates that the newly identified components function together with HDA6 and HDA19 and coregulate the expression of a number of genes.HDA6 and HDA19 were previously thought to repress gene transcription by histone deacetylation.We find that the histone deacetylase complexes can repress gene expression via both histone deacetylation-dependent and-independent mechanisms.In the mutants of histone deacetylase complexes,the expression of a number of stressinduced genes is up-regulated,and several mutants of the histone deacetylase complexes show severe retardation in growth.Considering that growth retardation is thought to be a trade-off for an increase in stress tolerance,we infer that the histone deacetylase complexes identified in this study prevent overexpression of stress-induced genes and thereby ensure normal growth of plants under nonstress conditions.展开更多
Dear Editor, Histone lysine methylation has received a great deal of attention from the chromatin field over the past 10 years. To date, histone lysine methylations have been demonstrated to play pivotal roles in near...Dear Editor, Histone lysine methylation has received a great deal of attention from the chromatin field over the past 10 years. To date, histone lysine methylations have been demonstrated to play pivotal roles in nearly all biological processes involving chromatin, including replication, transcription, DNA repair etc.展开更多
Repair of DNA double-strand break(DSB)is critical for the maintenance of genome integrity.A class of DSB-induced small RNAs(di RNAs)has been shown to play an important role in DSB repair.In humans,di RNAs are associat...Repair of DNA double-strand break(DSB)is critical for the maintenance of genome integrity.A class of DSB-induced small RNAs(di RNAs)has been shown to play an important role in DSB repair.In humans,di RNAs are associated with Ago2 and guide the recruitment of Rad51 to DSB sites to facilitate repair by homologous recombination(HR).Ago2 activity has been reported to be regulated by phosphorylation under normal and hypoxic conditions.However,the role of Ago2 phosphorylation in DNA damage repair is unexplored.Here,we show that S672,S828,T830,and S831 of human Ago2 are phosphorylated in response to ionizing radiation(IR).S672 A mutation of Ago2 leads to significant reduction in Rad51 foci formation and HR efficiency.We further show that defective association of Ago2 S672 A variant with DSB sites,instead of defects in di RNA and Rad51 binding,may account for decreased Rad51 foci formation and HR efficiency.Our study reveals a novel regulatory mechanism for the function of Ago2 in DNA repair.展开更多
Trimethylation of histone H3K4(H3K4me3)is widely distributed at numerous actively transcribed protein-coding genes throughout the genome.However,the interplay between H3K4me3 and other chromatin modifications in plant...Trimethylation of histone H3K4(H3K4me3)is widely distributed at numerous actively transcribed protein-coding genes throughout the genome.However,the interplay between H3K4me3 and other chromatin modifications in plants remains poorly understood.In this study,we show that the Arabidopsis thaliana ALFIN-LIKE(AL)proteins contain a C-terminal PHD finger capable of binding to H3K4me3 and a PHD-associated AL(PAL)domain that interacts with components of the Polycomb repressive complex 1,thereby facilitating H2A ubiquitination(H2Aub)at H3K4me3-enriched genes throughout the genome.Furthermore,we demonstrate that loss of function of SDG2,encoding a key histone H3K4 methyltransferase,leads to a reduction in H3K4me3 level,which subsequently causes a genome-wide decrease in H2Aub,revealing a strong association between H3K4me3 and H2Aub.Finally,we discover that the PAL domain of AL proteins interacts with various other chromatin-related proteins or complexes,including those involved in regulating H2A.Z deposition,H3K27me3 demethylation,histone deacetylation,and chromatin accessibility.Our genome-wide analysis suggests that the AL proteins play a crucial role in coordinating H3K4me3 with multiple other chromatin modifications across the genome.展开更多
Room-temperature flash sintering(FS)for ceramics is a highly efficient and energy-saving new ceramic sintering technique.Addressing the current challenges in room-temperature flash sintering research,such as small pro...Room-temperature flash sintering(FS)for ceramics is a highly efficient and energy-saving new ceramic sintering technique.Addressing the current challenges in room-temperature flash sintering research,such as small product sizes,shape limitations,and high power requirements,limits their real application in the FS industry.In particular,for dog bone shape and small size,which are usually smaller than 10 mm,no records of sizes larger than 20 mm have been reported.In this study,a novel flash sintering device based on a composite layered carbon electrode structure was developed to conduct large-diameter sample flash sintering at room temperature(RT)in an air atmosphere under a direct current(DC)voltage below 10o V.Specifically,room-temperatureflash sintering was achievedfor Zn0 ceramic disks with diameters of 40.0 mm and thicknesses of 1.80 mm,achieving a maximum relative density of 96.02%.Furthermore,room-temperature flash sintering was achieved for ZnO varistor ceramic disks with a diameter of 40.0 mm and a thickness of 1.93 mm,reaching a maximum relative density of 99.27%,a maximum voltage gradient of 330.5 V·mm^(-1),and the highest nonlinearity coefficient(a)of 23.0.Room-temperature flash sintering was also achieved for 3 mol%yttrium-doped zirconia(3YSZ)ceramic disks,achieving a maximum relative density of 98.48%.The proposed flash sintering device and corresponding process demonstrate broad applicability for the ceramics industry.展开更多
Although the mechanism of DNA methylationmediated gene silencing is extensively studied, relatively little is known about how promoter methylated genes are protected from transcriptional silencing. SUVH1, an Arabidops...Although the mechanism of DNA methylationmediated gene silencing is extensively studied, relatively little is known about how promoter methylated genes are protected from transcriptional silencing. SUVH1, an Arabidopsis Su(var)3-9 homolog, was previously shown to be required for the expression of a few promoter methylated genes. By chromatin immunoprecipitation combined with sequencing, we demonstrate that SUVH1 binds to methylated genomic loci targeted by RNA-directed DNA methylation. SUVH1 and its homolog SUVH3 function partially redundantly and interact with three DNAJ domain-containing homologs, SDJ1, SDJ2, and SDJ3, thus forming a complex which we named SUVH-SDJ. The SUVH-SDJ complex components are co-localized in a large number of methylated promoters and are required for the expression of a subset of promoter methylated genes. We demonstrate that the SUVHSDJ complex components have transcriptional activation activity. SUVH1 and SUVH3 function synergistically with SDJ1,SDJ2, and SDJ3 and are required for plant viability. This study reveals how the SUVH-SDJ complex protects promoter methylated genes from transcriptional silencing and suggests that the transcriptional activation of promoter methylated genes mediated by the SUVH-SDJ complex may play a critical role in plant growth and development.展开更多
In eukaryotes,MEDIATOR is a conserved multisubunit complex that links transcription factors and RNA polymerase II and that thereby facilitates transcriptional initiation.Although the composition of MEDIATOR has been w...In eukaryotes,MEDIATOR is a conserved multisubunit complex that links transcription factors and RNA polymerase II and that thereby facilitates transcriptional initiation.Although the composition of MEDIATOR has been well studied in yeast and mammals,relatively little is known about the composition of MEDIATOR in plants.By affinity purification followed by mass spectrometry,we identified 28 conserved MEDIATOR subunits in Arabidopsis thaliana,including putative MEDIATOR subunits that were not previously validated.Our results indicated that MED34,MED35,MED36,and MED37 are not Arabidopsis MEDIATOR subunits,as previously proposed.Our results also revealed that two homologous CBP/p300 histone acetyltransferases,HAC1 and HAC5(HAC1/5)are in fact plant-specific MEDIATOR subunits.The MEDIATOR subunits MED8 and MED25(MED8/25)are partially responsible for the association of MEDIATOR with HAC1/5,MED8/25 and HAC1/5 co-regulate gene expression and thereby affect flowering time and floral development.Our in vitro observations indicated that MED8 and HAC1 form liquid-like droplets by phase separation,and our in vivo observations indicated that these droplets co-localize in the nuclear bodies at a subset of nuclei.The formation of liquid-like droplets is required for MED8 to interact with RNA polymerase II.In summary,we have identified all of the components of Arabidopsis MEDIATOR and revealed the mechanism underlying the link of histone acetylation and transcriptional regulation.展开更多
The SAGA(Spt-Ada-Gcn5 acetyltransferase)complex is an evolutionarily conserved histone acetyltransferase complex that has a critical role in histone acetylation,gene expression,and various developmental processes in e...The SAGA(Spt-Ada-Gcn5 acetyltransferase)complex is an evolutionarily conserved histone acetyltransferase complex that has a critical role in histone acetylation,gene expression,and various developmental processes in eukaryotes.However,little is known about the composition and function of the SAGA complex in plants.In this study,we found that the SAGA complex in Arabidopsis thaliana contains not only conserved subunits but also four plant-specific subunits:three functionally redundant paralogs,SCSI,SCS2A,and SCS2B(SCS1/2A/2B),and a TAF-like subunit,TAFL.Mutations in SCS1/2A/2B lead to defective phenotypes similar to those caused by mutations in the genes encoding conserved SAGA subunits HAG1 and ADA2B,including delayed juvenile-to-adult phase transition,late flowering,and increased trichome density.Furthermore,we demonstrated that SCS1/2A/2B are required for the function of the SAGA complex in histone acetylation,thereby promoting the transcription of development-related genes.These results together suggest that SCS1/2A/2B are core subunits of the SAGA complex in Arabidopsis.Compared with SAGA complexes in other eukaryotes,the SAGA complexes in plants have evolved unique features that are necessary for normal growth and development.展开更多
Rapid developments in EHV/UHV transmission systems require a deeper understanding of the mechanism of long air gap discharge.Leader propagation is one of the main processes in long gap breakdown.In this paper,the lead...Rapid developments in EHV/UHV transmission systems require a deeper understanding of the mechanism of long air gap discharge.Leader propagation is one of the main processes in long gap breakdown.In this paper,the leader propagation characteristics of real size±800 kV UHVDC transmission tower gaps under positive switching impulse voltages(185/2290μs)are investigated.An integrated observation platform consisting of an impulse voltage divider,a coaxial shunt,a high-speed video camera,and a set of integrated optical electric field sensors(IOES),is established.The waveforms of impulse voltage,discharge current,electric field variation at specific positions,and time-resolved photographs of discharge morphology are recorded.Axial leader velocity and the relationship between leader advancements and injected charge are obtained.The typical value of leader stable propagation velocity is 1.7–2.2 cm/μs,which varies slightly with the gap length and applied voltage amplitude.The leader velocity in the re-illumination process is much higher,and is seen as varying from 5 cm/μs to 30 cm/μs,with an average value around 10 cm/μs.The charge in leader channel per unit length is 20–40μC/m,which illustrates a near-direct proportion relationship between discharge current and leader velocity.The observed parameters are important for further simulation of the tower gap breakdown processes.展开更多
LHP1 mediates recruitment of the PRC2 histone methyltransferase complex to chromatin and thereby facilitates maintenance of H3K27me3 on FLC, a key flowering repressor gene. Here, we report that the PWWP domain protei...LHP1 mediates recruitment of the PRC2 histone methyltransferase complex to chromatin and thereby facilitates maintenance of H3K27me3 on FLC, a key flowering repressor gene. Here, we report that the PWWP domain proteins （PDPs） interact with FVE and MSI5 to suppress FLC expression and thereby promote flowering. We demonstrated that FVE, MSI5, and PDP3 were co-purified with LHP1. The H3K27me3 level on FLC was decreased in the pdp mutants as welt as in the fve/ msi5 double mutant. This study suggests that PDPs function together with FVE and MSI5 to regulate the function of the PRC2 complex on FLC.展开更多
Trimethylated histone H3 lysine 27(H3 K27 me3)is a repressive histone marker that regulates a variety of developmental processes,including those that determine flowering time.However,relatively little is known about t...Trimethylated histone H3 lysine 27(H3 K27 me3)is a repressive histone marker that regulates a variety of developmental processes,including those that determine flowering time.However,relatively little is known about the mechanism of how H3 K27 me3 is recognized to regulate transcription.Here,we identified BAH domain-containing transcriptional regulator 1(BDT1)as an H3 K27 me3 reader.BDT1 is responsible for preventing flowering by suppressing the expression of flowering genes.Mutation of the H3 K27 me3 recognition sites in the BAH domain disrupted the binding of BDT1 to H3 K27 me3,leading to de-repression of H3 K27 me3-enriched flowering genes and an earlyflowering phenotype.We also found that BDT1 interacts with a family of PHD finger-containing proteins,which we named PHD1–6,and with CPL2,a Pol II carboxyl terminal domain(CTD)phosphatase responsible for transcriptional repression.Pull-down assays showed that the PHD finger-containing proteins can enhance the binding of BDT1 to the H3 K27 me3 peptide.Mutations in all of the PHD genes caused increased expression of flowering genes and an earlyflowering phenotype.This study suggests that the binding of BDT1 to the H3 K27 me3 peptide,which is enhanced by PHD proteins,is critical for preventing early flowering.展开更多
Lightning and lightning induced effects have significant influence on many aspects affecting the public, whichmakes the research of lightning and lightning protection very important. However, due to the strong randomn...Lightning and lightning induced effects have significant influence on many aspects affecting the public, whichmakes the research of lightning and lightning protection very important. However, due to the strong randomness andcomplex discharge mechanisms of lightning, the understanding of lightning is still far from satisfactory. On the basis ofthe International Conference on Lightning Protection 2014, this study gives a review of recent progress on lightningand lightning protection research covering the following aspects: lightning locating and observation, lightning physics,lightning electromagnetic transients, and lightning protection for various systems. The goals of this study are to givereaders an overall introduction to the recent progress in lightning and lightning protection research, and to motivatethem to conduct further studies to address the unsolved problems in lightning-related research.展开更多
文摘目的:收集关于神经示踪技术应用于实验针灸研究的相关文献,总结分析其在腧穴、经脉、脏腑等方面的应用状况。方法:本研究以"示踪技术OR神经示踪技术OR示踪剂OR神经示踪剂OR示踪OR神经示踪"和"针灸OR针刺OR电针OR耳针OR眼针OR经脉OR穴区OR腧穴OR穴位注射"为检索词检索中国知网(CNKI,1979-2017)、万方数据知识平台(Wan-Fang Data,1990-2017)、维普资讯中文期刊服务平台(VIP Date,1989-2017);以"neural tracing technique OR neuroanatomical tracing OR neuronal tracers"and"acupuncture OR electroacupuncture OR auricular acupuncture OR eye acupuncture OR meridians OR acupuncture points OR acupoint injection"为关键词检索英文数据库PubMed(1997-2017)。结果:共收录与本研究相关的文献94篇。其中使用最多的神经示踪剂是辣根过氧化物酶和霍乱毒素亚单位B,采用的实验动物有大鼠、家兔、猫和猴等,示踪剂的注射部位以腧穴居多。示踪剂注射后动物的存活时间从1 d到12周不等,所标记的神经成分包括感觉、运动和自主神经系统相关的神经元及其神经纤维。这些文献主要揭示了腧穴和脏腑的神经支配具有区域性和节段性特征,二者之间存在密切的神经解剖学联系,而其相关的神经元和神经纤维的化学特征(通过免疫荧光组织化学染色显示)与针灸作用途径密切相关。结论:应用神经示踪技术可以从神经通路/环路及其相关化学性质等不同角度更加深入地了解针灸的作用途径,这也为该项技术在将来的实验针灸研究中发挥更大的作用奠定了基础。
基金supported by the National Natural Science Foundation of China(32025003)by the National Key Research and Development Program of China(2016YFA0500801)from the Chinese Ministry of Science and Technology。
文摘The Arabidopsis thaliana RPD3-type histone deacetylases have been known to form conserved SIN3-type histone deacetylase complexes,but whether they form other types of complexes is unknown.Here,we perform affinity purification followed by mass spectrometry and demonstrate that the Arabidopsis RPD3-type histone deacetylases HDA6 and HDA19 interact with several previously uncharacterized proteins,thereby forming three types of plant-specific histone deacetylase complexes,which we named SANT,ESANT,and ARID.RNA-seq indicates that the newly identified components function together with HDA6 and HDA19 and coregulate the expression of a number of genes.HDA6 and HDA19 were previously thought to repress gene transcription by histone deacetylation.We find that the histone deacetylase complexes can repress gene expression via both histone deacetylation-dependent and-independent mechanisms.In the mutants of histone deacetylase complexes,the expression of a number of stressinduced genes is up-regulated,and several mutants of the histone deacetylase complexes show severe retardation in growth.Considering that growth retardation is thought to be a trade-off for an increase in stress tolerance,we infer that the histone deacetylase complexes identified in this study prevent overexpression of stress-induced genes and thereby ensure normal growth of plants under nonstress conditions.
文摘Dear Editor, Histone lysine methylation has received a great deal of attention from the chromatin field over the past 10 years. To date, histone lysine methylations have been demonstrated to play pivotal roles in nearly all biological processes involving chromatin, including replication, transcription, DNA repair etc.
基金supported by the National Natural Science Foundation of China(31401202)。
文摘Repair of DNA double-strand break(DSB)is critical for the maintenance of genome integrity.A class of DSB-induced small RNAs(di RNAs)has been shown to play an important role in DSB repair.In humans,di RNAs are associated with Ago2 and guide the recruitment of Rad51 to DSB sites to facilitate repair by homologous recombination(HR).Ago2 activity has been reported to be regulated by phosphorylation under normal and hypoxic conditions.However,the role of Ago2 phosphorylation in DNA damage repair is unexplored.Here,we show that S672,S828,T830,and S831 of human Ago2 are phosphorylated in response to ionizing radiation(IR).S672 A mutation of Ago2 leads to significant reduction in Rad51 foci formation and HR efficiency.We further show that defective association of Ago2 S672 A variant with DSB sites,instead of defects in di RNA and Rad51 binding,may account for decreased Rad51 foci formation and HR efficiency.Our study reveals a novel regulatory mechanism for the function of Ago2 in DNA repair.
基金supported by the National Natural Science Foundation of China to X.-J.H.(grant numbers 32025003 and 32470628).
文摘Trimethylation of histone H3K4(H3K4me3)is widely distributed at numerous actively transcribed protein-coding genes throughout the genome.However,the interplay between H3K4me3 and other chromatin modifications in plants remains poorly understood.In this study,we show that the Arabidopsis thaliana ALFIN-LIKE(AL)proteins contain a C-terminal PHD finger capable of binding to H3K4me3 and a PHD-associated AL(PAL)domain that interacts with components of the Polycomb repressive complex 1,thereby facilitating H2A ubiquitination(H2Aub)at H3K4me3-enriched genes throughout the genome.Furthermore,we demonstrate that loss of function of SDG2,encoding a key histone H3K4 methyltransferase,leads to a reduction in H3K4me3 level,which subsequently causes a genome-wide decrease in H2Aub,revealing a strong association between H3K4me3 and H2Aub.Finally,we discover that the PAL domain of AL proteins interacts with various other chromatin-related proteins or complexes,including those involved in regulating H2A.Z deposition,H3K27me3 demethylation,histone deacetylation,and chromatin accessibility.Our genome-wide analysis suggests that the AL proteins play a crucial role in coordinating H3K4me3 with multiple other chromatin modifications across the genome.
基金supported by the National Natural Science Foundation of China(No.52077118)the Open Fund of the State Key Laboratory of High-Efficiency and High-Quality Conversion for Electric Power(No.2024KF006)+2 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2024A1515012597)the State Grid Jiangxi Electric Power Company Science and Technology Project(No.52182025000H)the Jiangxi Key Research and Development Program(No.20243BBG71028).
文摘Room-temperature flash sintering(FS)for ceramics is a highly efficient and energy-saving new ceramic sintering technique.Addressing the current challenges in room-temperature flash sintering research,such as small product sizes,shape limitations,and high power requirements,limits their real application in the FS industry.In particular,for dog bone shape and small size,which are usually smaller than 10 mm,no records of sizes larger than 20 mm have been reported.In this study,a novel flash sintering device based on a composite layered carbon electrode structure was developed to conduct large-diameter sample flash sintering at room temperature(RT)in an air atmosphere under a direct current(DC)voltage below 10o V.Specifically,room-temperatureflash sintering was achievedfor Zn0 ceramic disks with diameters of 40.0 mm and thicknesses of 1.80 mm,achieving a maximum relative density of 96.02%.Furthermore,room-temperature flash sintering was achieved for ZnO varistor ceramic disks with a diameter of 40.0 mm and a thickness of 1.93 mm,reaching a maximum relative density of 99.27%,a maximum voltage gradient of 330.5 V·mm^(-1),and the highest nonlinearity coefficient(a)of 23.0.Room-temperature flash sintering was also achieved for 3 mol%yttrium-doped zirconia(3YSZ)ceramic disks,achieving a maximum relative density of 98.48%.The proposed flash sintering device and corresponding process demonstrate broad applicability for the ceramics industry.
基金supported by grants from National Key Research and Development Program of China (2016YFA0500801)
文摘Although the mechanism of DNA methylationmediated gene silencing is extensively studied, relatively little is known about how promoter methylated genes are protected from transcriptional silencing. SUVH1, an Arabidopsis Su(var)3-9 homolog, was previously shown to be required for the expression of a few promoter methylated genes. By chromatin immunoprecipitation combined with sequencing, we demonstrate that SUVH1 binds to methylated genomic loci targeted by RNA-directed DNA methylation. SUVH1 and its homolog SUVH3 function partially redundantly and interact with three DNAJ domain-containing homologs, SDJ1, SDJ2, and SDJ3, thus forming a complex which we named SUVH-SDJ. The SUVH-SDJ complex components are co-localized in a large number of methylated promoters and are required for the expression of a subset of promoter methylated genes. We demonstrate that the SUVHSDJ complex components have transcriptional activation activity. SUVH1 and SUVH3 function synergistically with SDJ1,SDJ2, and SDJ3 and are required for plant viability. This study reveals how the SUVH-SDJ complex protects promoter methylated genes from transcriptional silencing and suggests that the transcriptional activation of promoter methylated genes mediated by the SUVH-SDJ complex may play a critical role in plant growth and development.
基金supported by the National Natural Science Foundation of China(32025003)by the National Key Research and Development Program of China(2016YFA0500801)from the Chinese Ministry of Science and Technology。
文摘In eukaryotes,MEDIATOR is a conserved multisubunit complex that links transcription factors and RNA polymerase II and that thereby facilitates transcriptional initiation.Although the composition of MEDIATOR has been well studied in yeast and mammals,relatively little is known about the composition of MEDIATOR in plants.By affinity purification followed by mass spectrometry,we identified 28 conserved MEDIATOR subunits in Arabidopsis thaliana,including putative MEDIATOR subunits that were not previously validated.Our results indicated that MED34,MED35,MED36,and MED37 are not Arabidopsis MEDIATOR subunits,as previously proposed.Our results also revealed that two homologous CBP/p300 histone acetyltransferases,HAC1 and HAC5(HAC1/5)are in fact plant-specific MEDIATOR subunits.The MEDIATOR subunits MED8 and MED25(MED8/25)are partially responsible for the association of MEDIATOR with HAC1/5,MED8/25 and HAC1/5 co-regulate gene expression and thereby affect flowering time and floral development.Our in vitro observations indicated that MED8 and HAC1 form liquid-like droplets by phase separation,and our in vivo observations indicated that these droplets co-localize in the nuclear bodies at a subset of nuclei.The formation of liquid-like droplets is required for MED8 to interact with RNA polymerase II.In summary,we have identified all of the components of Arabidopsis MEDIATOR and revealed the mechanism underlying the link of histone acetylation and transcriptional regulation.
基金the National Natural Science Foundation of China(32025003)the National Key Research and Development Program of China(2016YFA0500801)from the Chinese Ministry of Science and Technology.
文摘The SAGA(Spt-Ada-Gcn5 acetyltransferase)complex is an evolutionarily conserved histone acetyltransferase complex that has a critical role in histone acetylation,gene expression,and various developmental processes in eukaryotes.However,little is known about the composition and function of the SAGA complex in plants.In this study,we found that the SAGA complex in Arabidopsis thaliana contains not only conserved subunits but also four plant-specific subunits:three functionally redundant paralogs,SCSI,SCS2A,and SCS2B(SCS1/2A/2B),and a TAF-like subunit,TAFL.Mutations in SCS1/2A/2B lead to defective phenotypes similar to those caused by mutations in the genes encoding conserved SAGA subunits HAG1 and ADA2B,including delayed juvenile-to-adult phase transition,late flowering,and increased trichome density.Furthermore,we demonstrated that SCS1/2A/2B are required for the function of the SAGA complex in histone acetylation,thereby promoting the transcription of development-related genes.These results together suggest that SCS1/2A/2B are core subunits of the SAGA complex in Arabidopsis.Compared with SAGA complexes in other eukaryotes,the SAGA complexes in plants have evolved unique features that are necessary for normal growth and development.
基金supported by the National Natural Science Foundation of China under Grant 51325703,51377094Fund of the National Priority Basic Research of China(2011CB209403)。
文摘Rapid developments in EHV/UHV transmission systems require a deeper understanding of the mechanism of long air gap discharge.Leader propagation is one of the main processes in long gap breakdown.In this paper,the leader propagation characteristics of real size±800 kV UHVDC transmission tower gaps under positive switching impulse voltages(185/2290μs)are investigated.An integrated observation platform consisting of an impulse voltage divider,a coaxial shunt,a high-speed video camera,and a set of integrated optical electric field sensors(IOES),is established.The waveforms of impulse voltage,discharge current,electric field variation at specific positions,and time-resolved photographs of discharge morphology are recorded.Axial leader velocity and the relationship between leader advancements and injected charge are obtained.The typical value of leader stable propagation velocity is 1.7–2.2 cm/μs,which varies slightly with the gap length and applied voltage amplitude.The leader velocity in the re-illumination process is much higher,and is seen as varying from 5 cm/μs to 30 cm/μs,with an average value around 10 cm/μs.The charge in leader channel per unit length is 20–40μC/m,which illustrates a near-direct proportion relationship between discharge current and leader velocity.The observed parameters are important for further simulation of the tower gap breakdown processes.
基金supported by the National Key Research and Development Program of China (2016YFA0500801)the 973 Program (2011CB812600) from the Chinese Ministry of Science and Technology (to X.J.H.)the National Natural Science Foundation of China (31370317 and 31571584 to B.W.)
文摘LHP1 mediates recruitment of the PRC2 histone methyltransferase complex to chromatin and thereby facilitates maintenance of H3K27me3 on FLC, a key flowering repressor gene. Here, we report that the PWWP domain proteins （PDPs） interact with FVE and MSI5 to suppress FLC expression and thereby promote flowering. We demonstrated that FVE, MSI5, and PDP3 were co-purified with LHP1. The H3K27me3 level on FLC was decreased in the pdp mutants as welt as in the fve/ msi5 double mutant. This study suggests that PDPs function together with FVE and MSI5 to regulate the function of the PRC2 complex on FLC.
基金supported by the National Natural Science Foundation of China(32025003)by the National Key Research and Development Program of China(2016YFA0500801)from the Chinese Ministry of Science and Technology。
文摘Trimethylated histone H3 lysine 27(H3 K27 me3)is a repressive histone marker that regulates a variety of developmental processes,including those that determine flowering time.However,relatively little is known about the mechanism of how H3 K27 me3 is recognized to regulate transcription.Here,we identified BAH domain-containing transcriptional regulator 1(BDT1)as an H3 K27 me3 reader.BDT1 is responsible for preventing flowering by suppressing the expression of flowering genes.Mutation of the H3 K27 me3 recognition sites in the BAH domain disrupted the binding of BDT1 to H3 K27 me3,leading to de-repression of H3 K27 me3-enriched flowering genes and an earlyflowering phenotype.We also found that BDT1 interacts with a family of PHD finger-containing proteins,which we named PHD1–6,and with CPL2,a Pol II carboxyl terminal domain(CTD)phosphatase responsible for transcriptional repression.Pull-down assays showed that the PHD finger-containing proteins can enhance the binding of BDT1 to the H3 K27 me3 peptide.Mutations in all of the PHD genes caused increased expression of flowering genes and an earlyflowering phenotype.This study suggests that the binding of BDT1 to the H3 K27 me3 peptide,which is enhanced by PHD proteins,is critical for preventing early flowering.
文摘Lightning and lightning induced effects have significant influence on many aspects affecting the public, whichmakes the research of lightning and lightning protection very important. However, due to the strong randomness andcomplex discharge mechanisms of lightning, the understanding of lightning is still far from satisfactory. On the basis ofthe International Conference on Lightning Protection 2014, this study gives a review of recent progress on lightningand lightning protection research covering the following aspects: lightning locating and observation, lightning physics,lightning electromagnetic transients, and lightning protection for various systems. The goals of this study are to givereaders an overall introduction to the recent progress in lightning and lightning protection research, and to motivatethem to conduct further studies to address the unsolved problems in lightning-related research.
