A concise total synthesis of secoisolariciresinol

A concise total synthesis of (R,R)-secoisolariciresinol was achieved in four steps, featuring a biomimetic β-β’ radical coupling of two dihydroferulic acid derivatives. The conversion of secoisolariciresinol to other related lignans was ongoing.     

NDM-1 encoded by a pNDM-HN380-like plasmid pNDM-BJ03 in clinical Enterobacter cloacae

A carbapenemase-producing Enterobacter cloacae hhy03 with a bla_NDM-1 and bla_SHV-12-coharboring plasmid was isolated from a sputum specimen of a patient. This is the third nucleotide sequence report of bla_NDM-1-harboring plasmid from Enterobacter cloacae that have caused lethal infections in China, indicating the spread of NDM-1 by IncX3 plasmid between Enterobacteriaceae.     

慢病毒介导shRNA沉默Nicastrin基因的人永生化角质形成细胞模型构建

目的 构建Nicastrin(NCT)基因的RNA干扰慢病毒表达载体,并在人永生化角质形成细胞(HaCaT细胞)上鉴定其沉默效率,构建NCT基因稳定下调的人永生化角质形成细胞模型,为后续研究NCT基因下调对角质形成细胞的生物学行为影响奠定实验基础.方法 设计3个靶向NCT基因特异性短发卡RNA(shRNA)表达序列并连接到慢病毒表达质粒pGLV3/H 1/GFP+ Puro中,成功构建慢病毒重组表达质粒,并通过测序鉴定.将构建的重组表达质粒与包装质粒共转染293T细胞,产生慢病毒颗粒,并测其滴度.将HaCaT细胞分为空白组(未感染病毒)、阴性对照组(NC组,感染空载病毒LV3-shNC)和干扰组(感染NCT-shRNA1、2、3慢病毒).流式细胞仪检测慢病毒转染效率,实时荧光定量PCR(qRT-PCR)、Western印迹检测靶基因的沉默效率,筛选出沉默效果最佳的干扰序列.结果 测序表明,NCT-shRNA慢病毒重组表达质粒构建成功.重组表达质粒与包装质粒共转染293T细胞后产生的慢病毒颗粒滴度为109 TU/ml.慢病毒感染HaCaT细胞后,流式细胞仪检测,慢病毒转染效率大于95％.qRT-PCR结果,与NC组相比,干扰组NCT mRNA表达量明显下降,其中NCT-shRNA1组NCT基因沉默效果最佳,干扰效率达到75％.Western印迹结果,与NC组相比,shRNA1组NCT蛋白表达抑制率为71.7％.结论 成功筛选出高效NCT-shRNA干扰序列,构建NCT-shRNA慢病毒重组表达载体,并构建NCT基因稳定下调的人永生化角质形成细胞模型.