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101.
Cheng-Jie Yang Zi-Long Song Masuo Goto Pei-Ling Hsu Xiao-Shuai Zhang Qian-Ru Yang Ying-Qian Liu Mei-Juan Wang Susan L. Morris-Natschke Xiao-Fei Shang Kuo-Hsiung Lee 《Bioorganic & medicinal chemistry letters》2017,27(20):4694-4697
Fluorination is a well-known strategy for improving the bioavailability of bioactive molecules in the lead optimization phase of drug discovery projects. In an attempt to improve the antitumor activity of camptothecins (CPTs), novel 10-fluoro-CPT derivatives were designed, synthesized and evaluated for cytotoxicity against five human cancer cell lines (A-549, MDA-MB-231, KB, KB-VIN and MCF-7). All of the derivatives showed more potent in vitro cytotoxic activity than the clinical CPT-derived drug irinotecan against the tumor cell lines tested, and most of them showed comparable or superior potency to topotecan. Remarkably, compounds 16b (IC50, 67.0 nM) and 19b (IC50, 99.2 nM) displayed the highest cytotoxicity against the multidrug-resistant (MDR) KB-VIN cell line and merit further development as preclinical drug candidates for treating cancer, including MDR phenotype. Our study suggested that incorporation of a fluorine atom into position 10 of CPT is an effective method for discovering new potent CPT derivatives. 相似文献
102.
Dianyuea C. Shang, S. Liao & Z. X. Zhang, a new monotypic genus of Salicaceae based on Flacourtia turbinata H. J. Dong & H. Peng, is described and illustrated. Morphologically, Dianyuea differs from Flacourtia Comm. ex L'Hér. by having six connate stamens, basal placentation and lobed seed appendages. All those features indicate that Dianyuea is allied with Scyphostegia Stapf. A molecular phylogenetic analysis using plastid trnL‐F, matK, and rbcL sequence data for representatives of 16 genera in Salicaceae s.l. shows that Dianyuea is sister to Scyphostegia. The new combination Dianyuea turbinata (H. J. Dong & H. Peng) C. Shang, S. Liao & Z. X. Zhang is proposed. 相似文献
103.
Concentration‐ and flux‐based dose–responses of isoprene emission from poplar leaves and plants exposed to an ozone concentration gradient 下载免费PDF全文
Xiangyang Yuan Zhaozhong Feng Shuo Liu Bo Shang Pin Li Yansen Xu Elena Paoletti 《Plant, cell & environment》2017,40(9):1960-1971
Concentration‐ and flux‐based O3 dose–responses of isoprene emission from single leaves and whole plants were developed. Two poplar clones differing in O3 sensitivity were exposed to five O3 levels in open‐top chambers for 97 d: charcoal‐filtered ambient air (CF), non‐filtered ambient air (NF) and NF plus 20 ppb (NF + 20), 40 ppb (NF + 40) and 60 ppb (NF + 60). At both leaf and plant level, isoprene emission was significantly decreased by NF + 40 and NF + 60 for both clones. Although intra‐specific variability was found when the emissions were up‐scaled to the whole plant, both leaf‐ and plant‐level emissions decreased linearly with increasing concentration‐based (AOT40, cumulative exposure to hourly O3 concentrations >40 ppb) and flux‐based indices (PODY, cumulative stomatal uptake of O3 > Y nmol O3 m?2 PLA s?1). AOT40‐ and POD7‐based dose–responses performed equally well. The two clones responded differently to AOT40 and similarly to PODY (with a slightly higher R2 for POD7) when the emission was expressed as change relative to clean air. We thus recommend POD7 as a large‐scale risk assessment metric to estimate isoprene emission responses to O3 in poplar. 相似文献
104.
In spectral analysis, a chemical component is usually identified by its characteristic spectra, especially the peaks. If two components have overlapping spectral peaks, they are generally considered to be indiscriminate in current analytical chemistry textbooks and related literature. However, if the intensities of the overlapping major spectral peaks are additive, and have different rates of change with respect to variations in the concentration of the individual components, a simple method, named the ‘common‐origin ray’, for the simultaneous determination of two components can be established. Several case studies highlighting its applications are presented. 相似文献
105.
Xiaochun Li Xiangxiang Fu Xulan Shang Wanxia Yang Shengzuo Fang 《Tree Genetics & Genomes》2017,13(4):80
Cyclocarya paliurus, a Chinese monotypic genus belonging to the Juglandaceae, exhibits a widespread distribution in southern China. To provide resource support for its future breeding and medicinal utilization, much information involving natural population succession and genetic diversity of C. paliurus should be obtained. In this study, the structures of 30 natural populations throughout its distribution were analyzed based on the investigation, showing the ratio of individuals with DBH < 40 cm accounting for 71.7%. Inter-simple sequence repeat (ISSR) and simple sequence repeat (SSR) were used for evaluation of 244 individuals from 29 natural populations. High-level polymorphism (100%) indicates high efficiency of two markers. Analysis demonstrated that genetic diversity (value of 0.18 for ISSR and 0.09 for SSR) was low among populations. While gene flow among populations reached 1.182 and 1.335 for ISSR and SSR, respectively, indicating genetic variations mainly existing within population. Twenty-six populations (size ≥5 individuals) were grouped into five clusters based on the combined ISSR and SSR loci. The value of Nei’s coefficient varying from 0.87 to 0.96 indicates small differentiation among groups. Furthermore, we speculate that C. paliurus is an expanding species in subtropical China (most of populations are increasing type (IP)) and discuss the strategy of germplasm conservation. 相似文献
106.
107.
植物钙/钙调素介导的信号转导系统 总被引:1,自引:0,他引:1
钙离子(Ca2+)是一种重要的第二信使, 参与调节植物的生长发育和对环境的适应。钙调素(CaM)和类钙调蛋白(CML)是一类最主要的Ca2+感受器, 虽然其自身没有催化活性, 但可通过调节下游靶蛋白的活性, 进而调控细胞的各种生理活动。该文总结了植物体内CaM结合蛋白(CBP)的生理功能、鉴定方法和调控机理, 以及CaM介导的信号转导途径, 包括蛋白磷酸化与去磷酸化、基因转录、离子运输、活性氧代谢、激素和磷脂信号等, 并对今后的研究方向进行了展望。 相似文献
108.
109.
共表达口蹄疫病毒衣壳前体蛋白P1-2A基因和蛋白酶3C基因牛肾细胞株的筛选及稳定性 总被引:2,自引:0,他引:2
[目的]筛选稳定表达口蹄疫病毒衣壳蛋白的牛肾细胞(Madin-Darby bovinekidney,MDBK)株.[方法]采用聚合酶链式反应(Polymerase chain reaction,PCR)方法从重组质粒pMD-P1-2A和pMD-3C中分别扩增口蹄疫病毒衣壳前体蛋白P1-2A基因和蛋白酶3C基因,将两基因依次插入逆转录病毒载体pBABE-puro.重组逆转录病毒载体pBABE-puro/P1-2A-3C和pVSV-G质粒载体用脂质体介导共转染GP2-293包装细胞.产生的重组逆转录病毒感染MDBK细胞后使用嘌呤霉素筛选抗性细胞.利用克隆环套取法得到单克隆细胞.经间接免疫荧光和酶联免疫吸附测定(Enzyme-linkedimmunosorbent assay,ELISA)方法检测MDBK细胞中衣壳蛋白的表达,并在电镜下观察口蹄疫病毒空衣壳.[结果]成功筛选到稳定表达口蹄疫病毒衣壳蛋白的MDBK细胞株,衣壳前体蛋白P1-2A在蛋白酶3C裂解作用下正确组装成空衣壳.[结论]该研究为口蹄疫亚单位疫苗的研制提供了实验材料. 相似文献
110.
采用RT-PCR技术从牛气管组织扩增出2400 bp的b1基因, 回收纯化连入PGEM-T载体, 测序。用Expasy软件对b1基因的抗原性进行分析, 选取胞外区334~861 bp的配体结合区与6×His融合, 在大肠杆菌中大规模诱导表达, 并经Ni2+亲和柱层析纯化。通过SDS-PAGE鉴定后, 应用纯化蛋白免疫新西兰家兔, 获得效价在1:12 800以上的多抗, Western blotting鉴定表明此抗体可特异性的与表达的融合蛋白作用。 相似文献