Objective Junctophilin-2(JPH2)is an essential structural protein that maintains junctional membrane complexes(JMCs)in cardiomyocytes by tethering the plasma membrane to the sarcoplasmic reticulum,thereby facilitating ...Objective Junctophilin-2(JPH2)is an essential structural protein that maintains junctional membrane complexes(JMCs)in cardiomyocytes by tethering the plasma membrane to the sarcoplasmic reticulum,thereby facilitating excitationcontraction(E-C)coupling.Mutations in JPH2 have been associated with hypertrophic cardiomyopathy(HCM),but the molecular mechanisms governing its membrane-binding properties and the functional relevance of its membrane occupation and recognition nexus(MORN)repeat motifs remain incompletely understood.This study aimed to elucidate the structural basis of JPH2 membrane association and its implications for HCM pathogenesis.Methods A recombinant N-terminal fragment of mouse JPH2(residues 1-440),encompassing the MORN repeats and an adjacent helical region,was purified under near-physiological buffer conditions.X-ray crystallography was employed to determine the structure of the JPH2 MORN-Helix domain.Sequence conservation analysis across species and junctophilin isoforms was performed to assess the evolutionary conservation of key structural features.Functional membrane-binding assays were conducted using liposome co-sedimentation and cell-based localization studies in COS7 and HeLa cells.In addition,site-directed mutagenesis targeting positively charged residues and known HCM-associated mutations,including R347C,was used to evaluate their effects on membrane interaction and subcellular localization.Results The crystal structure of the mouse JPH2 MORN-Helix domain was resolved at 2.6Å,revealing a compact,elongated architecture consisting of multiple tandem MORN motifs arranged in a curved configuration,forming a continuous hydrophobic core stabilized by alternating aromatic residues.A C-terminalα-helix further reinforced structural integrity.Conservation analysis identified the inner groove of the MORN array as a highly conserved surface,suggesting its role as a protein-binding interface.A flexible linker segment enriched in positively charged residues,located adjacent to the MORN motifs,was found to mediate direct electrostatic interactions with negatively charged phospholipid membranes.Functional assays demonstrated that mutation of these basic residues impaired membrane association,while the HCM-linked R347C mutation completely abolished membrane localization in cellular assays,despite preserving the overall MORN-Helix fold in structural modeling.Conclusion This study provides structural insight into the membrane-binding mechanism of the cardiomyocyte-specific protein JPH2,highlighting the dual roles of its MORN-Helix domain in membrane anchoring and protein interactions.The findings clarify the structural basis for membrane targeting via a positively charged linker and demonstrate that disruption of this interaction—such as that caused by the R347C mutation—likely contributes to HCM pathogenesis.These results not only enhance current understanding of JPH2 function in cardiac E-C coupling but also offer a structural framework for future investigations into the assembly and regulation of JMCs in both physiological and disease contexts.展开更多
作为黄海的代表性冷温性鱼类,大头鳕(Gadus macrocephalus)的资源量近年逐渐上升趋势,其中幼鱼所占比重较大,种群丰度及补充都受到黄海冷水团的影响,作为2龄性成熟鱼种,探究其当年生和非当年生幼鱼分布和生长的季节变化及与黄海冷水团...作为黄海的代表性冷温性鱼类,大头鳕(Gadus macrocephalus)的资源量近年逐渐上升趋势,其中幼鱼所占比重较大,种群丰度及补充都受到黄海冷水团的影响,作为2龄性成熟鱼种,探究其当年生和非当年生幼鱼分布和生长的季节变化及与黄海冷水团的关系对了解大头鳕的资源变动有重要意义。本研究基于2016年10月、2017年5和8月的调查结果,分析了黄海冷水团存在时期的海洋环境特征与大头鳕幼鱼分布及生长特征的关系。研究显示,春季,幼鱼主要分布于青海渔场、石岛渔场和连青石渔场,非当年生幼鱼和当年生幼鱼随栖息地水深分别呈东西两区块分布。夏季,幼鱼主要位于122.00°E以东、底温低于10℃的黄海中部较深海域,有少部分分布于黄海北部,这与黄海冷水团强盛时期南北低温中心的位置有关。秋季,黄海北部大头鳕幼鱼的渔获量明显减少,仅在石岛渔场和连青石渔场大头鳕的种群密度仍较高。广义相加模型(Generalized Additive Models,GAM)分析结果显示,温度和盐度对大头鳕幼鱼的资源丰度指数(单位捕捞努力量渔获量(Catch Per Unit Effort,CPUE))有显著影响,当栖息地水域盐度在31.90和32.80附近,底温在8.5℃左右时,大头鳕幼鱼的CPUE较高。体长-体重关系显示,春季,幼鱼呈负异速生长,夏秋季呈正异速生长,黄海冷水团强盛时期较高的有机质含量及初级生产力造成的丰富饵料可能是导致大头鳕夏秋季b值较高的原因,因此黄海冷水团的季节变化对大头鳕的分布和生长均有显著影响。展开更多
锂电池的荷电状态(state of charge, SOC)作为锂电池的重要参数之一,其估算精度对锂电池的管理有很大影响。扩展卡尔曼滤波算法作为常用的SOC估算方法,忽略了噪声变化对SOC估算的影响,在运用时会出现噪声误差累积的情况。自适应扩展卡...锂电池的荷电状态(state of charge, SOC)作为锂电池的重要参数之一,其估算精度对锂电池的管理有很大影响。扩展卡尔曼滤波算法作为常用的SOC估算方法,忽略了噪声变化对SOC估算的影响,在运用时会出现噪声误差累积的情况。自适应扩展卡尔曼滤波算法能对扩展卡尔曼滤波算法估算SOC时的噪声进行修正。实验结果表明,该方法能有效提高SOC估算精度。在动态应力测试工况下,估算精度提高2%;在北京公交纯电动客车动态应力测试工况下,估算精度提高0.39%。该方法能够提高实际应用中的SOC估算精度,从而可以提高锂电池的管理效率。展开更多
The forming performance of sheet metals in the deep-drawing process with ultrasonic vibrations can be improved by the surface effect between the sheet metal and the die.A sheet metal friction test with ultrasonic vibr...The forming performance of sheet metals in the deep-drawing process with ultrasonic vibrations can be improved by the surface effect between the sheet metal and the die.A sheet metal friction test with ultrasonic vibrations is performed to explore the cause of the surface effect.The frictional characteristics are investigated,and the corresponding friction expressions are established based on the contact mechanics and the elastic–plastic contact model for rough surfaces.Friction is caused by the elastic–plastic deformation of contacting asperities under normal loads.The actual contacting region between two surfaces increases with normal loads,whereas the normal distance decreases.The normal distance between the contacting surfaces is changed,asperities generate a tangential deformation with ultrasonic vibrations,and the friction coefficient is eventually altered.Ultrasonic vibrations are applied on a 40Cr steel punch at the frequency of 20 kHz and the amplitude of 4.2μm.In the friction tests,the punch is perpendicular to the surface of the magnesium alloy AZ31B sheet metals and is sliding with a relative velocity of 1 mm/s.The test results show that the friction coefficient is decreased by approximately 40%and the theoretical values are in accordance with the test values;Ultrasonic vibrations can clearly reduce wear and improve the surface quality of parts.展开更多
文摘Objective Junctophilin-2(JPH2)is an essential structural protein that maintains junctional membrane complexes(JMCs)in cardiomyocytes by tethering the plasma membrane to the sarcoplasmic reticulum,thereby facilitating excitationcontraction(E-C)coupling.Mutations in JPH2 have been associated with hypertrophic cardiomyopathy(HCM),but the molecular mechanisms governing its membrane-binding properties and the functional relevance of its membrane occupation and recognition nexus(MORN)repeat motifs remain incompletely understood.This study aimed to elucidate the structural basis of JPH2 membrane association and its implications for HCM pathogenesis.Methods A recombinant N-terminal fragment of mouse JPH2(residues 1-440),encompassing the MORN repeats and an adjacent helical region,was purified under near-physiological buffer conditions.X-ray crystallography was employed to determine the structure of the JPH2 MORN-Helix domain.Sequence conservation analysis across species and junctophilin isoforms was performed to assess the evolutionary conservation of key structural features.Functional membrane-binding assays were conducted using liposome co-sedimentation and cell-based localization studies in COS7 and HeLa cells.In addition,site-directed mutagenesis targeting positively charged residues and known HCM-associated mutations,including R347C,was used to evaluate their effects on membrane interaction and subcellular localization.Results The crystal structure of the mouse JPH2 MORN-Helix domain was resolved at 2.6Å,revealing a compact,elongated architecture consisting of multiple tandem MORN motifs arranged in a curved configuration,forming a continuous hydrophobic core stabilized by alternating aromatic residues.A C-terminalα-helix further reinforced structural integrity.Conservation analysis identified the inner groove of the MORN array as a highly conserved surface,suggesting its role as a protein-binding interface.A flexible linker segment enriched in positively charged residues,located adjacent to the MORN motifs,was found to mediate direct electrostatic interactions with negatively charged phospholipid membranes.Functional assays demonstrated that mutation of these basic residues impaired membrane association,while the HCM-linked R347C mutation completely abolished membrane localization in cellular assays,despite preserving the overall MORN-Helix fold in structural modeling.Conclusion This study provides structural insight into the membrane-binding mechanism of the cardiomyocyte-specific protein JPH2,highlighting the dual roles of its MORN-Helix domain in membrane anchoring and protein interactions.The findings clarify the structural basis for membrane targeting via a positively charged linker and demonstrate that disruption of this interaction—such as that caused by the R347C mutation—likely contributes to HCM pathogenesis.These results not only enhance current understanding of JPH2 function in cardiac E-C coupling but also offer a structural framework for future investigations into the assembly and regulation of JMCs in both physiological and disease contexts.
文摘作为黄海的代表性冷温性鱼类,大头鳕(Gadus macrocephalus)的资源量近年逐渐上升趋势,其中幼鱼所占比重较大,种群丰度及补充都受到黄海冷水团的影响,作为2龄性成熟鱼种,探究其当年生和非当年生幼鱼分布和生长的季节变化及与黄海冷水团的关系对了解大头鳕的资源变动有重要意义。本研究基于2016年10月、2017年5和8月的调查结果,分析了黄海冷水团存在时期的海洋环境特征与大头鳕幼鱼分布及生长特征的关系。研究显示,春季,幼鱼主要分布于青海渔场、石岛渔场和连青石渔场,非当年生幼鱼和当年生幼鱼随栖息地水深分别呈东西两区块分布。夏季,幼鱼主要位于122.00°E以东、底温低于10℃的黄海中部较深海域,有少部分分布于黄海北部,这与黄海冷水团强盛时期南北低温中心的位置有关。秋季,黄海北部大头鳕幼鱼的渔获量明显减少,仅在石岛渔场和连青石渔场大头鳕的种群密度仍较高。广义相加模型(Generalized Additive Models,GAM)分析结果显示,温度和盐度对大头鳕幼鱼的资源丰度指数(单位捕捞努力量渔获量(Catch Per Unit Effort,CPUE))有显著影响,当栖息地水域盐度在31.90和32.80附近,底温在8.5℃左右时,大头鳕幼鱼的CPUE较高。体长-体重关系显示,春季,幼鱼呈负异速生长,夏秋季呈正异速生长,黄海冷水团强盛时期较高的有机质含量及初级生产力造成的丰富饵料可能是导致大头鳕夏秋季b值较高的原因,因此黄海冷水团的季节变化对大头鳕的分布和生长均有显著影响。
文摘锂电池的荷电状态(state of charge, SOC)作为锂电池的重要参数之一,其估算精度对锂电池的管理有很大影响。扩展卡尔曼滤波算法作为常用的SOC估算方法,忽略了噪声变化对SOC估算的影响,在运用时会出现噪声误差累积的情况。自适应扩展卡尔曼滤波算法能对扩展卡尔曼滤波算法估算SOC时的噪声进行修正。实验结果表明,该方法能有效提高SOC估算精度。在动态应力测试工况下,估算精度提高2%;在北京公交纯电动客车动态应力测试工况下,估算精度提高0.39%。该方法能够提高实际应用中的SOC估算精度,从而可以提高锂电池的管理效率。
基金Projects(51775480,51305385)supported by the National Natural Science Foundation of ChinaProject(E2018203143)supported by the Natural Science Foundation of Hebei Province,China
文摘The forming performance of sheet metals in the deep-drawing process with ultrasonic vibrations can be improved by the surface effect between the sheet metal and the die.A sheet metal friction test with ultrasonic vibrations is performed to explore the cause of the surface effect.The frictional characteristics are investigated,and the corresponding friction expressions are established based on the contact mechanics and the elastic–plastic contact model for rough surfaces.Friction is caused by the elastic–plastic deformation of contacting asperities under normal loads.The actual contacting region between two surfaces increases with normal loads,whereas the normal distance decreases.The normal distance between the contacting surfaces is changed,asperities generate a tangential deformation with ultrasonic vibrations,and the friction coefficient is eventually altered.Ultrasonic vibrations are applied on a 40Cr steel punch at the frequency of 20 kHz and the amplitude of 4.2μm.In the friction tests,the punch is perpendicular to the surface of the magnesium alloy AZ31B sheet metals and is sliding with a relative velocity of 1 mm/s.The test results show that the friction coefficient is decreased by approximately 40%and the theoretical values are in accordance with the test values;Ultrasonic vibrations can clearly reduce wear and improve the surface quality of parts.
