DNA–RNA hybrid(DRH) plays important roles in many biological processes. Here, we use a thermodynamic theory to analyze the free energy and unpeeling properties of the overstretching transition for the DRH molecule an...DNA–RNA hybrid(DRH) plays important roles in many biological processes. Here, we use a thermodynamic theory to analyze the free energy and unpeeling properties of the overstretching transition for the DRH molecule and compare the results with double-helix DNA. We report that the RNA strand of DRH is easier to get unpeeled than the DNA strand while the difficulty in unpeeling the double helix DNA lies in between. We also investigate the sequence effect, such as GC content and purine content, on the properties of unpeeling the DRH. Further, to study the temperature effect, the forcetemperature phase diagram of DRH and DNA are calculated and compared. Finally, using a kinetic model, we calculate the force–extension curves in the DRH stretching and relaxation process under different pulling rates and temperatures. Our results show that both pulling rate and temperature have important influences on the stretching and relaxation kinetics of unpeeling the DRH. Putting all these results together, our work provides a comprehensive view of both the thermodynamics and kinetics in DRH overstretching.展开更多
R-loops are RNA-DNA-hybrid-containing nucleic acids with important cellular roles.Deregulation of R-loop dynamics can lead to DNA damage and genome instability1,which has been linked to the action of endonucleases suc...R-loops are RNA-DNA-hybrid-containing nucleic acids with important cellular roles.Deregulation of R-loop dynamics can lead to DNA damage and genome instability1,which has been linked to the action of endonucleases such as XPG2-4.However,the mechanisms and cellular consequences of such processing have remained unclear.展开更多
目的观察龙葵碱对S180和H22荷瘤小鼠肿瘤细胞DNA和RNA的影响。方法将S180和H22荷瘤小鼠分为龙葵碱37.50、18.75、9.37 m g/kg组、阴性对照组和环磷酰胺(30 m g/kg)组,各组sc给药。利用激光共聚焦扫描显微镜,分别测定各组肿瘤细胞中的DNA...目的观察龙葵碱对S180和H22荷瘤小鼠肿瘤细胞DNA和RNA的影响。方法将S180和H22荷瘤小鼠分为龙葵碱37.50、18.75、9.37 m g/kg组、阴性对照组和环磷酰胺(30 m g/kg)组,各组sc给药。利用激光共聚焦扫描显微镜,分别测定各组肿瘤细胞中的DNA和RNA。结果龙葵碱(37.50、18.75 m g/kg)组对S180和H22小鼠肿瘤细胞RNA和DNA的比值均有明显的降低作用。结论龙葵碱降低S180和H22小鼠肿瘤细胞RNA和DNA的比值可能是其抗肿瘤作用机制之一。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11674403)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.31700809)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.18lgzd16)the Open Fund of the State Key Laboratory of Optoelectronic Materials and Technologies,Sun Yat-sen University
文摘DNA–RNA hybrid(DRH) plays important roles in many biological processes. Here, we use a thermodynamic theory to analyze the free energy and unpeeling properties of the overstretching transition for the DRH molecule and compare the results with double-helix DNA. We report that the RNA strand of DRH is easier to get unpeeled than the DNA strand while the difficulty in unpeeling the double helix DNA lies in between. We also investigate the sequence effect, such as GC content and purine content, on the properties of unpeeling the DRH. Further, to study the temperature effect, the forcetemperature phase diagram of DRH and DNA are calculated and compared. Finally, using a kinetic model, we calculate the force–extension curves in the DRH stretching and relaxation process under different pulling rates and temperatures. Our results show that both pulling rate and temperature have important influences on the stretching and relaxation kinetics of unpeeling the DRH. Putting all these results together, our work provides a comprehensive view of both the thermodynamics and kinetics in DRH overstretching.
文摘R-loops are RNA-DNA-hybrid-containing nucleic acids with important cellular roles.Deregulation of R-loop dynamics can lead to DNA damage and genome instability1,which has been linked to the action of endonucleases such as XPG2-4.However,the mechanisms and cellular consequences of such processing have remained unclear.
文摘目的观察龙葵碱对S180和H22荷瘤小鼠肿瘤细胞DNA和RNA的影响。方法将S180和H22荷瘤小鼠分为龙葵碱37.50、18.75、9.37 m g/kg组、阴性对照组和环磷酰胺(30 m g/kg)组,各组sc给药。利用激光共聚焦扫描显微镜,分别测定各组肿瘤细胞中的DNA和RNA。结果龙葵碱(37.50、18.75 m g/kg)组对S180和H22小鼠肿瘤细胞RNA和DNA的比值均有明显的降低作用。结论龙葵碱降低S180和H22小鼠肿瘤细胞RNA和DNA的比值可能是其抗肿瘤作用机制之一。
