ISO 21809-3:2008标准要求石油天然气管道现场节点涂装前应进行PQT(工艺评定试验)和PPT(预生产试验)试验。IMPP是一种新型海管节点涂层,涂装工艺复杂,应用项目少。为了保证IMPP(注射成型聚丙烯)涂装成功,必须在PQT和PPT中严格执行标准...ISO 21809-3:2008标准要求石油天然气管道现场节点涂装前应进行PQT(工艺评定试验)和PPT(预生产试验)试验。IMPP是一种新型海管节点涂层,涂装工艺复杂,应用项目少。为了保证IMPP(注射成型聚丙烯)涂装成功,必须在PQT和PPT中严格执行标准和规格书的规定,检测各项参数保证满足要求。文中介绍了某国际海管铺设项目中节点IMPP涂装PQT和PPT试验过程和结果,分析了过程中发现的问题,对类似的新型海管节点涂装的PQT和PPT实施提出了建议。与常规节点涂层的PQT和PPT相比,IMPP涂层试验过程和样品制备过程难度更大,在阴极剥离和热老化试验等测试中需要使用专用的工具和设备。展开更多
Paraquat is one of the most widely used nonselective herbicides and has elicited the emergence of para-quat-resistant weeds.However,the molecular mechanisms of paraquat resistance are not completely un-derstood.Here w...Paraquat is one of the most widely used nonselective herbicides and has elicited the emergence of para-quat-resistant weeds.However,the molecular mechanisms of paraquat resistance are not completely un-derstood.Here we report the Arabidopsis gain-of-function mutant pqt15-D with significantly enhanced resistance to paraquat and the corresponding gene PQT15,which encodes the Multidrug and Toxic Extru-sion(MATE)transporter DTX6.A point mutation at+932 bp in DTX6 causes a G311E amino acid substitution,enhancing the paraquat resistance ofpqt15-D,and overexpression of DTX6/PQT15 in the wild-type plants also results in strong paraquat resistance.Moreover,heterologous expression of DTX6 and DTX6-D in Es-cherichia coil significantly enhances bacterial resistance to paraquat.Importantly,overexpression of DTX6-D enables Arabidopsis plants to tolerate 4 mM paraquat,a near-commercial application level.DTX6/PQT15 is localized in the plasma membrane and endomembrane,and functions as a paraquat efflux transporter as demonstrated by paraquat efflux assays with isolated protoplasts and bacterial cells.Taken together,our results demonstrate that DTX6/PQT15 is an efflux transporter that confers paraquat resis-tance by exporting paraquat out of the cytosol.These findings reveal a molecular mechanism of paraquat resistance in higher plants and provide a promising candidate gene for engineering paraquat-resistant crops.展开更多
基金supported by grants from the National Natural Science Foundation of China(grant no.31770273).
文摘Paraquat is one of the most widely used nonselective herbicides and has elicited the emergence of para-quat-resistant weeds.However,the molecular mechanisms of paraquat resistance are not completely un-derstood.Here we report the Arabidopsis gain-of-function mutant pqt15-D with significantly enhanced resistance to paraquat and the corresponding gene PQT15,which encodes the Multidrug and Toxic Extru-sion(MATE)transporter DTX6.A point mutation at+932 bp in DTX6 causes a G311E amino acid substitution,enhancing the paraquat resistance ofpqt15-D,and overexpression of DTX6/PQT15 in the wild-type plants also results in strong paraquat resistance.Moreover,heterologous expression of DTX6 and DTX6-D in Es-cherichia coil significantly enhances bacterial resistance to paraquat.Importantly,overexpression of DTX6-D enables Arabidopsis plants to tolerate 4 mM paraquat,a near-commercial application level.DTX6/PQT15 is localized in the plasma membrane and endomembrane,and functions as a paraquat efflux transporter as demonstrated by paraquat efflux assays with isolated protoplasts and bacterial cells.Taken together,our results demonstrate that DTX6/PQT15 is an efflux transporter that confers paraquat resis-tance by exporting paraquat out of the cytosol.These findings reveal a molecular mechanism of paraquat resistance in higher plants and provide a promising candidate gene for engineering paraquat-resistant crops.
