The comet assay was performed on mouse and human spermatozoa to examine the effect of alkaline DNA unwinding time. The spermatozoa were treated in vitrowith the DNA-damaging agents, methyl methanesulfonate （MMS） or ...The comet assay was performed on mouse and human spermatozoa to examine the effect of alkaline DNA unwinding time. The spermatozoa were treated in vitrowith the DNA-damaging agents, methyl methanesulfonate （MMS） or hydrogen peroxide （Hz02）, and then embedded in agarose gel on glass sl ides. The slides were immersed in alkaline solution （〉pH 13） for 1, 5, 10 and 20 min, and then subjected to the electrophoresis under neutral conditions. In mouse spermatozoa, comet tails seen in solvent controls became brighter and longer as the alkaline DNA unwinding time increased. However, in the MMS-treated mouse spermatozoa, a smaller difference in the damage from that in the solvent control was seen with time within a dose. DNA damage induced by H2O2 could also be detected accurately after alkali treatment for 1-20 min. In human spermatozoa, DNA damage induced by MMS and H2O2 could be detected in a dose-dependent manner after alkali treatment for 1 min. The ability of the comet assay to detect DNA damage was not adversely affected by the short period （1 min） of the alkaline DNA unwinding time.展开更多
A fuzzy controller of the winding/unwinding control system used in jig-dyeing machine is introduced,which is superior to the one with conventional optimal PID controller in convergence speed and stability.Its mathemat...A fuzzy controller of the winding/unwinding control system used in jig-dyeing machine is introduced,which is superior to the one with conventional optimal PID controller in convergence speed and stability.Its mathematical model and transfer function are presented based on mechanism of the winding/unwinding control system.Simulation of the fuzzy controller carried out in the MATLAB(Simulink)environment proves that the control system based on fuzzy controller is superior in quality,precision and operation to a conventional optimal PID controller.The outlined experimental results also show the effectiveness and the robustness of the fuzzy PID controller in good dynamic performance,high robustness to parameter variation and disturbance.展开更多
Studies were performed to determine the extent of nuclear DNA degradation induced by iron, iron-ascorbate, or iron-bleomycin under aerobic conditions in a model system using isolated rat liver nuclei. The effects of f...Studies were performed to determine the extent of nuclear DNA degradation induced by iron, iron-ascorbate, or iron-bleomycin under aerobic conditions in a model system using isolated rat liver nuclei. The effects of five antioxidants (catalase, superoxide dismutase, dimethyl sulfoxide, glutathione and diallyl sulfide) on this oxidative nuclear damage were also investigated. At the 0.05 level for statistical significance, iron induced concentration-dependent DNA degradation, and this effect was enhanced by ascorbate and bleomycin. The antioxidants catalase, dimethyl sulfoxide, and diallyl sulfide significantly reduced the iron-ascorbate-induced DNA damage, whereas superoxide dismutase and dimethyl sulfoxide significantly reduced iron-bleomycin-induced damage. Glutathione significantly increased the iron-bleomycin-induced DNA damage. These results suggest that the reactive oxygen species generated by iron, iron-ascorbate, and iron-bleomycin are responsible for the DNA strand breaks in isolated rat liver nuclei.展开更多
The COVID-19 pandemic has underscored the importance of in-depth research into the proteins encoded by coronaviruses(CoV),particularly the highly conserved nonstructural CoV proteins(nsp).Among these,the nsp13 helicas...The COVID-19 pandemic has underscored the importance of in-depth research into the proteins encoded by coronaviruses(CoV),particularly the highly conserved nonstructural CoV proteins(nsp).Among these,the nsp13 helicase of severe pathogenic MERS-CoV,SARS-CoV-2,and SARS-CoV is one of the most preserved CoV nsp.Utilizing single-molecule FRET,we discovered that MERS-CoV nsp13 unwinds DNA in distinct steps of about 9 bp when ATP is employed.If a different nucleotide is introduced,these steps diminish to 3−4 bp.Dwell-time analysis revealed 3−4 concealed steps within each unwinding process,which suggests the hydrolysis of 3−4 dTTP.Combining our observations with previous studies,we propose an unwinding model of CoV nsp13 helicase.This model suggests that the elongated and adaptable 1B-stalk of nsp13 may enable the 1B remnants to engage with the unwound single-stranded DNA,even as the helicase core domain has advanced over 3−4 bp,thereby inducing accumulated strain on the nsp13-DNA complex.Our findings provide a foundational framework for determining the unwinding mechanism of this unique helicase family.展开更多
Background:Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)emerged in December 2019 and has led to a global coronavirus disease 2019(COVID-19)pandemic.Currently,incomplete understanding of how SARS-CoV-2 ar...Background:Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)emerged in December 2019 and has led to a global coronavirus disease 2019(COVID-19)pandemic.Currently,incomplete understanding of how SARS-CoV-2 arrogates the host cell to establish its life cycle has led to slow progress in the development of effective drugs.Results:In this study,we found that SARS-CoV-2 hijacks the host protein EWSR1(Ewing Sarcoma breakpoint region 1/EWS RNA binding protein 1)to promote the activity of its helicase NSP13 to facilitate viral propagation.NSP13 is highly conserved among coronaviruses and is crucial for virus replication,providing chemical energy to unwind viral RNA replication intermediates.Treatment with different SARS-CoV-2 NSP13 inhibitors in multi-ple cell lines infected with SARS-CoV-2 effectively suppressed SARS-CoV-2 infection.Using affinity-purification mass spectrometry,the RNA binding protein EWSR1 was then identified as a potent host factor that physically associated with NSP13.Furthermore,silencing EWSR1 dramatically reduced virus replication at both viral RNA and protein levels.Mechanistically,EWSR1 was found to bind to the NTPase domain of NSP13 and potentially enhance its dsRNA unwinding ability.Conclusions:Our results pinpoint EWSR1 as a novel host factor for NSP13 that could potentially be used for drug repurposing as a therapeutic target for COVID-19.展开更多
文摘The comet assay was performed on mouse and human spermatozoa to examine the effect of alkaline DNA unwinding time. The spermatozoa were treated in vitrowith the DNA-damaging agents, methyl methanesulfonate （MMS） or hydrogen peroxide （Hz02）, and then embedded in agarose gel on glass sl ides. The slides were immersed in alkaline solution （〉pH 13） for 1, 5, 10 and 20 min, and then subjected to the electrophoresis under neutral conditions. In mouse spermatozoa, comet tails seen in solvent controls became brighter and longer as the alkaline DNA unwinding time increased. However, in the MMS-treated mouse spermatozoa, a smaller difference in the damage from that in the solvent control was seen with time within a dose. DNA damage induced by H2O2 could also be detected accurately after alkali treatment for 1-20 min. In human spermatozoa, DNA damage induced by MMS and H2O2 could be detected in a dose-dependent manner after alkali treatment for 1 min. The ability of the comet assay to detect DNA damage was not adversely affected by the short period （1 min） of the alkaline DNA unwinding time.
文摘A fuzzy controller of the winding/unwinding control system used in jig-dyeing machine is introduced,which is superior to the one with conventional optimal PID controller in convergence speed and stability.Its mathematical model and transfer function are presented based on mechanism of the winding/unwinding control system.Simulation of the fuzzy controller carried out in the MATLAB(Simulink)environment proves that the control system based on fuzzy controller is superior in quality,precision and operation to a conventional optimal PID controller.The outlined experimental results also show the effectiveness and the robustness of the fuzzy PID controller in good dynamic performance,high robustness to parameter variation and disturbance.
文摘Studies were performed to determine the extent of nuclear DNA degradation induced by iron, iron-ascorbate, or iron-bleomycin under aerobic conditions in a model system using isolated rat liver nuclei. The effects of five antioxidants (catalase, superoxide dismutase, dimethyl sulfoxide, glutathione and diallyl sulfide) on this oxidative nuclear damage were also investigated. At the 0.05 level for statistical significance, iron induced concentration-dependent DNA degradation, and this effect was enhanced by ascorbate and bleomycin. The antioxidants catalase, dimethyl sulfoxide, and diallyl sulfide significantly reduced the iron-ascorbate-induced DNA damage, whereas superoxide dismutase and dimethyl sulfoxide significantly reduced iron-bleomycin-induced damage. Glutathione significantly increased the iron-bleomycin-induced DNA damage. These results suggest that the reactive oxygen species generated by iron, iron-ascorbate, and iron-bleomycin are responsible for the DNA strand breaks in isolated rat liver nuclei.
基金supported by CRP-ICGEB Research Grant 2019(Grant number:CRP/CHN19-02)National Key Research and Development Program of China(Grant number:2016YFD0500300)supported by the Special Coronavirus(COVID-19)Research Pilot Grant Program from University of Cincinnati College of Medicine.
文摘The COVID-19 pandemic has underscored the importance of in-depth research into the proteins encoded by coronaviruses(CoV),particularly the highly conserved nonstructural CoV proteins(nsp).Among these,the nsp13 helicase of severe pathogenic MERS-CoV,SARS-CoV-2,and SARS-CoV is one of the most preserved CoV nsp.Utilizing single-molecule FRET,we discovered that MERS-CoV nsp13 unwinds DNA in distinct steps of about 9 bp when ATP is employed.If a different nucleotide is introduced,these steps diminish to 3−4 bp.Dwell-time analysis revealed 3−4 concealed steps within each unwinding process,which suggests the hydrolysis of 3−4 dTTP.Combining our observations with previous studies,we propose an unwinding model of CoV nsp13 helicase.This model suggests that the elongated and adaptable 1B-stalk of nsp13 may enable the 1B remnants to engage with the unwound single-stranded DNA,even as the helicase core domain has advanced over 3−4 bp,thereby inducing accumulated strain on the nsp13-DNA complex.Our findings provide a foundational framework for determining the unwinding mechanism of this unique helicase family.
基金This work was supported by grants from the Na-tional Science Fund for Distinguished Young Schol-ars(82025022)the Central Charity Fund of Chinese Academy of Medical Science(2020-PT310-009)+1 种基金the Sci-ence and Technology Innovation Committee of Shenzhen Municipality(2020A1111350032)the China Post-doctoral Science Foundation(2021M693359).
文摘Background:Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)emerged in December 2019 and has led to a global coronavirus disease 2019(COVID-19)pandemic.Currently,incomplete understanding of how SARS-CoV-2 arrogates the host cell to establish its life cycle has led to slow progress in the development of effective drugs.Results:In this study,we found that SARS-CoV-2 hijacks the host protein EWSR1(Ewing Sarcoma breakpoint region 1/EWS RNA binding protein 1)to promote the activity of its helicase NSP13 to facilitate viral propagation.NSP13 is highly conserved among coronaviruses and is crucial for virus replication,providing chemical energy to unwind viral RNA replication intermediates.Treatment with different SARS-CoV-2 NSP13 inhibitors in multi-ple cell lines infected with SARS-CoV-2 effectively suppressed SARS-CoV-2 infection.Using affinity-purification mass spectrometry,the RNA binding protein EWSR1 was then identified as a potent host factor that physically associated with NSP13.Furthermore,silencing EWSR1 dramatically reduced virus replication at both viral RNA and protein levels.Mechanistically,EWSR1 was found to bind to the NTPase domain of NSP13 and potentially enhance its dsRNA unwinding ability.Conclusions:Our results pinpoint EWSR1 as a novel host factor for NSP13 that could potentially be used for drug repurposing as a therapeutic target for COVID-19.
文摘以隔膜分切机中的放卷张力控制为研究对象,针对放卷系统非线性、强耦合以及参数时变等特性导致的张力波动问题,提出一种基于自抗扰控制(active disturbance rejection control,ADRC)的串级控制方案.首先,采取串级控制结构,以高动态性能的速度内环将传动机构的摩擦等非线性扰动对于张力的影响进行有效隔离;然后,由于速度内环的控制周期短、频率高,将ADRC的扩张状态观测器(extended state observer,ESO)放在内环,可有效减小扰动补偿的延时,进一步提高控制带宽和动态性能;最后,张力外环引入ADRC的安排过渡过程和非线性状态误差反馈(nonlinear state error feedback,NLSEF)的措施,能够有效缓解张力控制中存在的快速性与超调的矛盾,对隔膜特性和卷径测量噪声等缓变扰动对于张力的影响有很好的补偿效果.仿真和实验结果表明,所提出串级控制器具有良好的动态性能和抗干扰能力,能够更好地适应隔膜分切机不同工况下的张力控制要求.
