Genome editing is revolutionizing plant research and crop breeding.Sequence-specific nucleases(SSNs)such as zinc finger nuclease(ZFN)and TAL effector nuclease(TALEN)have been used to create site-specific DNA double-st...Genome editing is revolutionizing plant research and crop breeding.Sequence-specific nucleases(SSNs)such as zinc finger nuclease(ZFN)and TAL effector nuclease(TALEN)have been used to create site-specific DNA double-strand breaks and to achieve precise DNA modifications by promoting homology-directed repair(HDR)(Steinert et al.,2016;Voytas,2013).Later,RNA-guided SSNs such as CRISPR-Cas9,Cas12a,Cas12b,and their variants were applied for genome editing in plants(Li et al.,2013;Nekrasov et alM 2013;Tang et al.,2017;Zhong et al.,2019;Ming et al.,2020;Tang et al.,2019).However,HDR relies on simultaneous delivery of SSNs and DNA donors,which has been challenging in plants(Steinert et al.,2016;Zhang et aL,2019).Another challenge for realizing efficient HDR in plants is that DNA repair favors nonhomologous end joining(NHEJ)pathways over HDR in most cell types(Puchta,2005;Qi et al.,2013).展开更多
Low thermal expansion superalloys have been used for a number of years in a variety of applications, including gas turbine engines. The low thermal expansion characteristics of the most widely used class of materials ...Low thermal expansion superalloys have been used for a number of years in a variety of applications, including gas turbine engines. The low thermal expansion characteristics of the most widely used class of materials are derived from the ferromagnetic characteristics of Ni, Fe, and Co-based austenitic matrices containing little or no Cr.Alloy developments have been aimed at improving the oxidation resistance and stress accelerated grain boundary oxygen (SAGBO) attack.INCONEL alloy 783 is an oxidation resistant, low coefficient of thermal expansion superalloy developed for gas turbine applications. Alloy 783 represents a culmination in the development, of an alloy system with very high alumtnum content that, in addition to forming γ′,causes βaluminide phase precipitation in the austenitic matrix.This type of structure can be processed to resist both SAGBO and general oxidation,while providing low thermal expansion and useful mechanical properties up to 700℃.Key aspects of the alloy's development are presented.展开更多
有效的净化方式是获取兽药多残留高质量分析结果的重要前提。本文建立了Oasis PRiME HLB净化后经液质联用同时测定动物源性食品中β-受体激动剂类、喹诺酮类、磺胺类、氯霉素类、大环内酯类、镇静剂类、硝基咪唑类、阿维菌素类、抗病毒...有效的净化方式是获取兽药多残留高质量分析结果的重要前提。本文建立了Oasis PRiME HLB净化后经液质联用同时测定动物源性食品中β-受体激动剂类、喹诺酮类、磺胺类、氯霉素类、大环内酯类、镇静剂类、硝基咪唑类、阿维菌素类、抗病毒类、四环素类、非甾体类、青霉素类、头孢类物质的兽药多残留检测方法。试样用含0.2%甲酸的80%乙腈水提取及Oasis PRiME HLB净化后,经InfinityLab Poroshell 120 EC-C18色谱柱分离,三重四极杆液质联用系统检测。结果表明,13大类69种兽药残留在0.1~50 ng/mL浓度范围内线性关系良好(R2≥0.99),基质匹配或内标法定量的回收率为84.2%~113%,相对标准偏差均<8.9%。展开更多
Prime-editing systems have the capability to perform efficient and precise genome editing in human cells.In this study,we first developed a plant prime editor 2(pPE2)system and test its activity by generating a target...Prime-editing systems have the capability to perform efficient and precise genome editing in human cells.In this study,we first developed a plant prime editor 2(pPE2)system and test its activity by generating a targeted mutation on an HPT^(-ATG) reporter in rice.Our results showed that the pPE2 system could induce programmable editing at different genome sites.In transgenic T0 plants,pPE2-generated mutants occurred with 0%–31.3%frequency,suggesting that the efficiency of pPE2 varied greatly at different genomic sites and with prime-editing guide RNAs of diverse structures.To optimize editing efficiency,guide RNAs were introduced into the pPE2 system following the PE3 and PE3b strategy in human cells.However,at the genomic sites tested in this study,pPE3 systems generated only comparable or even lower editing frequencies.Furthemore,we developed a surrogate pPE2 system by incorporating the HPT^(-ATG) reporter to enrich the prime-edited cells.The nucleotide editing was easily detected in the resistant calli transformed with the surrogate pPE2 system,presumably due to the enhanced screening efficiency of edited cells.Taken together,our results indicate that plant prime-editing systems we developed could provide versatile and flexible editing in rice genome.展开更多
建立了超高效液相色谱串联质谱法同时测定56种动物源性兽药残留物的分析方法。以乙腈-0.5%乙酸水溶液(85:15,V/V)为提取溶剂,采用固相萃取柱(Oasis PRi ME HLB)进行样品净化,通过UPLC-MS/MS分析测定,基质曲线外标法定量。方法定量限为1....建立了超高效液相色谱串联质谱法同时测定56种动物源性兽药残留物的分析方法。以乙腈-0.5%乙酸水溶液(85:15,V/V)为提取溶剂,采用固相萃取柱(Oasis PRi ME HLB)进行样品净化,通过UPLC-MS/MS分析测定,基质曲线外标法定量。方法定量限为1.0μg/kg(喹诺酮类)、1.5μg/kg(糖皮质类)、10μg/kg(磺胺类)、1.0μg/kg(β-受体激动剂类)。56种兽药残留物在牛肉、猪肉、鸡肉和奶等基质样品中回收率范围为63.2%~101.5%,基质标准工作曲线线性相关系数大于0.937,精密度RSD<15%(n=3)。方法适用于动物源性食品中兽药残留物的分析。展开更多
目的建立高效液相色谱串联质谱法快速检测鸡蛋中硝基咪唑类药物残留量的分析方法。方法以0.1%甲酸乙腈为提取溶剂,加入盐析剂分层后,用Waters Oasis PRiME HLB法净化,用乙腈和0.1%(V:V)甲酸水溶液作为流动相进行梯度洗脱, C18色谱柱分离...目的建立高效液相色谱串联质谱法快速检测鸡蛋中硝基咪唑类药物残留量的分析方法。方法以0.1%甲酸乙腈为提取溶剂,加入盐析剂分层后,用Waters Oasis PRiME HLB法净化,用乙腈和0.1%(V:V)甲酸水溶液作为流动相进行梯度洗脱, C18色谱柱分离,在高效液相色谱-串联质谱仪上采用电喷雾正离子扫描模式检测,基质匹配标准曲线外标法定量。结果该方法在0.5~100 ng/mL范围内具有良好线性关系, 10种硝基咪唑类药物相关系数均大于(r^2)>0.99,方法检出限在0.1~0.3μg/kg范围,定量限在0.3~0.5μg/kg范围。3个浓度水平1.0、5.0、10.0μg/kg加标,平均回收率分别为82.5%~119.1%、80.7%~112.3%、80.6%~118.5%,相对标准偏差(relative standard deviation, RSD)为1.2%~9.1%。结论该方法具有快速、简便、准确、灵敏的特点,适用于鸡蛋中硝基咪唑残留量的分析检测,可用于日常大批量快速筛查工作,有效提高日常工作效率。展开更多
文摘Genome editing is revolutionizing plant research and crop breeding.Sequence-specific nucleases(SSNs)such as zinc finger nuclease(ZFN)and TAL effector nuclease(TALEN)have been used to create site-specific DNA double-strand breaks and to achieve precise DNA modifications by promoting homology-directed repair(HDR)(Steinert et al.,2016;Voytas,2013).Later,RNA-guided SSNs such as CRISPR-Cas9,Cas12a,Cas12b,and their variants were applied for genome editing in plants(Li et al.,2013;Nekrasov et alM 2013;Tang et al.,2017;Zhong et al.,2019;Ming et al.,2020;Tang et al.,2019).However,HDR relies on simultaneous delivery of SSNs and DNA donors,which has been challenging in plants(Steinert et al.,2016;Zhang et aL,2019).Another challenge for realizing efficient HDR in plants is that DNA repair favors nonhomologous end joining(NHEJ)pathways over HDR in most cell types(Puchta,2005;Qi et al.,2013).
文摘Low thermal expansion superalloys have been used for a number of years in a variety of applications, including gas turbine engines. The low thermal expansion characteristics of the most widely used class of materials are derived from the ferromagnetic characteristics of Ni, Fe, and Co-based austenitic matrices containing little or no Cr.Alloy developments have been aimed at improving the oxidation resistance and stress accelerated grain boundary oxygen (SAGBO) attack.INCONEL alloy 783 is an oxidation resistant, low coefficient of thermal expansion superalloy developed for gas turbine applications. Alloy 783 represents a culmination in the development, of an alloy system with very high alumtnum content that, in addition to forming γ′,causes βaluminide phase precipitation in the austenitic matrix.This type of structure can be processed to resist both SAGBO and general oxidation,while providing low thermal expansion and useful mechanical properties up to 700℃.Key aspects of the alloy's development are presented.
文摘有效的净化方式是获取兽药多残留高质量分析结果的重要前提。本文建立了Oasis PRiME HLB净化后经液质联用同时测定动物源性食品中β-受体激动剂类、喹诺酮类、磺胺类、氯霉素类、大环内酯类、镇静剂类、硝基咪唑类、阿维菌素类、抗病毒类、四环素类、非甾体类、青霉素类、头孢类物质的兽药多残留检测方法。试样用含0.2%甲酸的80%乙腈水提取及Oasis PRiME HLB净化后,经InfinityLab Poroshell 120 EC-C18色谱柱分离,三重四极杆液质联用系统检测。结果表明,13大类69种兽药残留在0.1~50 ng/mL浓度范围内线性关系良好(R2≥0.99),基质匹配或内标法定量的回收率为84.2%~113%,相对标准偏差均<8.9%。
基金funded by the Genetically Modified Breeding Major Projects(no.2019ZX08010003-001-008 and no.2016ZX08010-002-008)the National Natural Science Foundation of China(no.U19A2022).
文摘Prime-editing systems have the capability to perform efficient and precise genome editing in human cells.In this study,we first developed a plant prime editor 2(pPE2)system and test its activity by generating a targeted mutation on an HPT^(-ATG) reporter in rice.Our results showed that the pPE2 system could induce programmable editing at different genome sites.In transgenic T0 plants,pPE2-generated mutants occurred with 0%–31.3%frequency,suggesting that the efficiency of pPE2 varied greatly at different genomic sites and with prime-editing guide RNAs of diverse structures.To optimize editing efficiency,guide RNAs were introduced into the pPE2 system following the PE3 and PE3b strategy in human cells.However,at the genomic sites tested in this study,pPE3 systems generated only comparable or even lower editing frequencies.Furthemore,we developed a surrogate pPE2 system by incorporating the HPT^(-ATG) reporter to enrich the prime-edited cells.The nucleotide editing was easily detected in the resistant calli transformed with the surrogate pPE2 system,presumably due to the enhanced screening efficiency of edited cells.Taken together,our results indicate that plant prime-editing systems we developed could provide versatile and flexible editing in rice genome.
文摘建立了超高效液相色谱串联质谱法同时测定56种动物源性兽药残留物的分析方法。以乙腈-0.5%乙酸水溶液(85:15,V/V)为提取溶剂,采用固相萃取柱(Oasis PRi ME HLB)进行样品净化,通过UPLC-MS/MS分析测定,基质曲线外标法定量。方法定量限为1.0μg/kg(喹诺酮类)、1.5μg/kg(糖皮质类)、10μg/kg(磺胺类)、1.0μg/kg(β-受体激动剂类)。56种兽药残留物在牛肉、猪肉、鸡肉和奶等基质样品中回收率范围为63.2%~101.5%,基质标准工作曲线线性相关系数大于0.937,精密度RSD<15%(n=3)。方法适用于动物源性食品中兽药残留物的分析。
文摘目的建立高效液相色谱串联质谱法快速检测鸡蛋中硝基咪唑类药物残留量的分析方法。方法以0.1%甲酸乙腈为提取溶剂,加入盐析剂分层后,用Waters Oasis PRiME HLB法净化,用乙腈和0.1%(V:V)甲酸水溶液作为流动相进行梯度洗脱, C18色谱柱分离,在高效液相色谱-串联质谱仪上采用电喷雾正离子扫描模式检测,基质匹配标准曲线外标法定量。结果该方法在0.5~100 ng/mL范围内具有良好线性关系, 10种硝基咪唑类药物相关系数均大于(r^2)>0.99,方法检出限在0.1~0.3μg/kg范围,定量限在0.3~0.5μg/kg范围。3个浓度水平1.0、5.0、10.0μg/kg加标,平均回收率分别为82.5%~119.1%、80.7%~112.3%、80.6%~118.5%,相对标准偏差(relative standard deviation, RSD)为1.2%~9.1%。结论该方法具有快速、简便、准确、灵敏的特点,适用于鸡蛋中硝基咪唑残留量的分析检测,可用于日常大批量快速筛查工作,有效提高日常工作效率。
