哨兵(Sentinel)-6A海洋测高卫星搭载了GPS/Galileo双模接收机,为研究基于全球导航卫星系统多星座的低轨卫星精密定轨提供了契机。固定载波相位模糊度可提升低轨卫星的定轨精度,利用在轨实测数据研究GPS/Galileo双系统组合以及模糊度固...哨兵(Sentinel)-6A海洋测高卫星搭载了GPS/Galileo双模接收机,为研究基于全球导航卫星系统多星座的低轨卫星精密定轨提供了契机。固定载波相位模糊度可提升低轨卫星的定轨精度,利用在轨实测数据研究GPS/Galileo双系统组合以及模糊度固定对低轨卫星运动学定轨精度的影响。分别采用欧洲定轨中心(Center for Orbit Determination in Europe,CODE)、法国国家空间研究中心(Centre National d’Etudes Spatiales,CNES)、德国地学研究中心(German Research Centre for Geosciences,GFZ)和中国武汉大学(Wuhan University,WHU)发布的观测值偏差及对应的精密星历和钟差产品开展单接收机模糊度固定。结果表明:GPS/Galileo双系统组合可明显改善定轨几何构型。双系统组合浮点解轨道三维精度优于30 mm,相对于GPS单系统提升超过20%。模糊度固定显著提升了运动学定轨精度,组合固定解轨道精度优于20 mm,相对于GPS提升30%。基于CODE、CNES和GFZ产品的GPS和Galileo单系统模糊度固定率分别优于93%和95%,WHU产品的Galileo固定率则偏低。利用卫星激光测距(satellite laser ranging,SLR)观测数据对运动学定轨结果进行检核,单系统固定解轨道SLR残差均方根误差(root mean square,RMS)为13~15 mm,双系统组合固定解RMS则达到12~14 mm,提升超过10%。展开更多
BACKGROUND Hepatocellular carcinoma(HCC)is a prevalent malignant tumor with a poor prognosis,which is often associated with chronic hepatitis B virus infection in China.Our previous study has shown that long non-codin...BACKGROUND Hepatocellular carcinoma(HCC)is a prevalent malignant tumor with a poor prognosis,which is often associated with chronic hepatitis B virus infection in China.Our previous study has shown that long non-coding RNA semaphorin 6Aantisense RNA 1(SEMA6A-AS1)was significantly downregulated in hepatitis B virus-related HCC and associated with poor prognosis.AIM To explore the underlying mechanism of SEMA6A-AS1 in HCC progression.METHODS The expression levels of SEMA6A-AS1 and SEMA6A were detected using quantitative polymerase chain reaction,immunohistochemistry and Western blot.A growth curve,colony formation,wound-healing and transwell(with or without Matrigel)assays were respectively performed to assess the proliferation,migration and invasion abilities of HCC cells.Cell cycle and apoptosis assays were performed by flow cytometry.To investigate the potential mechanism underpinning SEMA6A-AS1,we utilized tagged RNA affinity purification,dual luciferase reporter assay and immunofluorescence.RESULTS Downregulation of SEMA6A-AS1 in HCC was negatively correlated with SEMA6A protein expression.SEMA6A was upregulated in HCC and correlated with high alpha-fetoprotein level,high Edmondson-Steiner grade and poor prognosis.SEMA6A-AS1 significantly inhibited the proliferation,migration and invasion of HCC cells by combining with SEMA6A mRNA and promoting its degradation.SEMA6A protein promoted the proliferation,migration and invasion of HCC cells by regulating the actin cytoskeleton.CONCLUSION Our findings suggest that SEMA6A-AS1 can inhibit HCC progression through decreasing SEMA6A expression by promoting its mRNA degradation.SEMA6A-AS1 may be a prognostic biomarker and therapeutic target for HCC.展开更多
YT521-B同源结构域家族成员2(YTH domain family protein2,YTHDF2)是一种m6A阅读蛋白,可通过与m6A修饰的RNA特异性结合并介导其降解,从而影响基因表达,参与多种生理和病理过程。目前发现YTHDF2在炎性反应和多种炎症性疾病中的异常表达,...YT521-B同源结构域家族成员2(YTH domain family protein2,YTHDF2)是一种m6A阅读蛋白,可通过与m6A修饰的RNA特异性结合并介导其降解,从而影响基因表达,参与多种生理和病理过程。目前发现YTHDF2在炎性反应和多种炎症性疾病中的异常表达,通过调节靶RNA的表达和信号通路的激活参与炎症性疾病的发生、发展。本文就YTHDF2的结构、功能以及在炎症性疾病发生、发展与药物治疗效应中的作用和相关分子发生机制进行综述。展开更多
文摘哨兵(Sentinel)-6A海洋测高卫星搭载了GPS/Galileo双模接收机,为研究基于全球导航卫星系统多星座的低轨卫星精密定轨提供了契机。固定载波相位模糊度可提升低轨卫星的定轨精度,利用在轨实测数据研究GPS/Galileo双系统组合以及模糊度固定对低轨卫星运动学定轨精度的影响。分别采用欧洲定轨中心(Center for Orbit Determination in Europe,CODE)、法国国家空间研究中心(Centre National d’Etudes Spatiales,CNES)、德国地学研究中心(German Research Centre for Geosciences,GFZ)和中国武汉大学(Wuhan University,WHU)发布的观测值偏差及对应的精密星历和钟差产品开展单接收机模糊度固定。结果表明:GPS/Galileo双系统组合可明显改善定轨几何构型。双系统组合浮点解轨道三维精度优于30 mm,相对于GPS单系统提升超过20%。模糊度固定显著提升了运动学定轨精度,组合固定解轨道精度优于20 mm,相对于GPS提升30%。基于CODE、CNES和GFZ产品的GPS和Galileo单系统模糊度固定率分别优于93%和95%,WHU产品的Galileo固定率则偏低。利用卫星激光测距(satellite laser ranging,SLR)观测数据对运动学定轨结果进行检核,单系统固定解轨道SLR残差均方根误差(root mean square,RMS)为13~15 mm,双系统组合固定解RMS则达到12~14 mm,提升超过10%。
基金Supported by Natural Science Foundation of Hunan Province,No.2021JJ41048 and No.S2019JJQNJJ2012and Changsha Natural Science Foundation,No.kq2208400.
文摘BACKGROUND Hepatocellular carcinoma(HCC)is a prevalent malignant tumor with a poor prognosis,which is often associated with chronic hepatitis B virus infection in China.Our previous study has shown that long non-coding RNA semaphorin 6Aantisense RNA 1(SEMA6A-AS1)was significantly downregulated in hepatitis B virus-related HCC and associated with poor prognosis.AIM To explore the underlying mechanism of SEMA6A-AS1 in HCC progression.METHODS The expression levels of SEMA6A-AS1 and SEMA6A were detected using quantitative polymerase chain reaction,immunohistochemistry and Western blot.A growth curve,colony formation,wound-healing and transwell(with or without Matrigel)assays were respectively performed to assess the proliferation,migration and invasion abilities of HCC cells.Cell cycle and apoptosis assays were performed by flow cytometry.To investigate the potential mechanism underpinning SEMA6A-AS1,we utilized tagged RNA affinity purification,dual luciferase reporter assay and immunofluorescence.RESULTS Downregulation of SEMA6A-AS1 in HCC was negatively correlated with SEMA6A protein expression.SEMA6A was upregulated in HCC and correlated with high alpha-fetoprotein level,high Edmondson-Steiner grade and poor prognosis.SEMA6A-AS1 significantly inhibited the proliferation,migration and invasion of HCC cells by combining with SEMA6A mRNA and promoting its degradation.SEMA6A protein promoted the proliferation,migration and invasion of HCC cells by regulating the actin cytoskeleton.CONCLUSION Our findings suggest that SEMA6A-AS1 can inhibit HCC progression through decreasing SEMA6A expression by promoting its mRNA degradation.SEMA6A-AS1 may be a prognostic biomarker and therapeutic target for HCC.
文摘YT521-B同源结构域家族成员2(YTH domain family protein2,YTHDF2)是一种m6A阅读蛋白,可通过与m6A修饰的RNA特异性结合并介导其降解,从而影响基因表达,参与多种生理和病理过程。目前发现YTHDF2在炎性反应和多种炎症性疾病中的异常表达,通过调节靶RNA的表达和信号通路的激活参与炎症性疾病的发生、发展。本文就YTHDF2的结构、功能以及在炎症性疾病发生、发展与药物治疗效应中的作用和相关分子发生机制进行综述。
