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921.
Using nicking DNA endonuclease (NiDE), we developed a novel technique to clone DNA fragments into plasmids. We created a NiDE cassette consisting of two inverted NiDE substrate sites sandwiching an asymmetric four-base sequence, and NiDE cleavage resulted in 14-base single-stranded termini at both ends of the vector and insert. This method can therefore be used as a ligation-independent cloning strategy to generate recombinant constructs rapidly. In addition, we designed and constructed a simple and specific vector from an Escherichia coli plasmid back-bone to complement this cloning method. By cloning cDNAs into this modified vector, we confirmed the predicted feasibility and applicability of this cloning method. 相似文献
922.
In eukaryotes, small noncoding RNA molecules of 16–29 nucleotides in length play crucial roles in the regulation of gene expression.
Some 377 sequences representing rice pseudo-microRNAs (miRNAs) are available in release 13.0 of the miRBase sequence database
() and are grouped into 143 families. Most newly deposited miRNA sequences are likely to be species-specific. To understand
the relationship between miRNAs and transposable elements (TEs) in rice, the RepeatMasker application () was used to screen single-stranded precursor miRNA (pre-miRNA) sequences. This analysis revealed that 33.1% of miRNAs and
36.4% of miRNA families are associated with interspersed repeats, and most of them are species-specific. Furthermore, multiple
miRNA families can be encoded by the same TE class. Alignment analysis revealed that miR439 originated from an MuDR4-OS TE,
which amplified and diversified in the genome as an inverted repeat of the core sequence followed by multiple repeats. Multiple
copies of miR445 and its complexity originate from and are driven by the DNA/Tourist TE class. These results provide an important
contribution to the elucidation of TE-driven mechanisms that regulate the species specificity and complexity of rice miRNAs. 相似文献
923.
924.
Yingfeng Du Yiran Jin Pengwei Liu Xiaowei Zhang Xiaona Sheng Xiaowei Shi Qiao Wang Lantong Zhang 《Phytochemical analysis : PCA》2010,21(5):416-427
Introduction – Isodon nervosa is a commonly used traditional Chinese medicine including diterpenoids, phenolic acids, triterpenoids and volatile oil. Qualitative and quantitative analysis of multi‐components is important for its quality control. Objective – To establish a liquid chromatography–electrospray ionisation–mass spectrometry method for simultaneous analysis of 20 bioactive constituents of Isodon nervosa in different places of China and different parts of this herb. Methodology – The optimal chromatographic conditions were achieved on a C18 column (250 × 4.6 mm, 5 µm) with with linear gradient elution with 0.1% aqueous formic acid : methanol containing 0.1% formic acid at a flow‐rate of 0.7 mL/min in 15 min. The identification and quantification of those analytes were achieved on a hybrid quadrupole linear ion trap mass spectrometer. Multiple‐reaction monitoring scanning was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. Full validation of the method was carried out (linearity, precision, accuracy, limit of detection and limit of quantification). Results – The results indicated that the method was simple, rapid, specific and reliable. The proposed method was successfully applied for the qualitative and quantitative analysis of 20 chemical compositions in Isodon nervosa samples. Conclusion – Twenty chemical compositions in 21 batches of wild and cultivated Isodon nervosa samples from different sources had great variation in the contents. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
925.
Li-Xia Cheng Jiang-Jiang Tang Hui Luo Xiao-Ling Jin Fang Dai Jie Yang Yi-Ping Qian Xiu-Zhuang Li Bo Zhou 《Bioorganic & medicinal chemistry letters》2010,20(8):2417-2420
Eight hydroxyl-substituted Schiff bases with the different number and position of hydroxyl group on the two asymmetric aromatic rings (A and B rings) were prepared by the reaction between the corresponding aromatic aldehyde and aniline. Their antioxidant effects against the stable galvinoxyl radical (GO) in ethyl acetate and methanol, and 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH)-induced DNA strand breakage, and their antiproliferative effects on human hepatoma HepG2 cells, were investigated. Structure–activity relationship analysis demonstrates that o-dihydroxyl groups on the aromatic A ring and 4-hydroxyl group attached to the aromatic B ring contribute critically to the antioxidant and antiproliferative activities. 相似文献
926.
Bin Ma Kevin M. Guckian Edward Yin-Shiang Lin Wen-Cherng Lee Daniel Scott Gnanasambandam Kumaravel Timothy L. Macdonald Kevin R. Lynch Cheryl Black Sowmya Chollate Kyungmin Hahm Gregg Hetu Ping Jin Yi Luo Ellen Rohde Anthony Rossomando Robert Scannevin Joy Wang Chunhua Yang 《Bioorganic & medicinal chemistry letters》2010,20(7):2264-2269
Modifying FTY720, an immunosuppressant modulator, led to a new series of well phosphorylated tetralin analogs as potent S1P1 receptor agonists. The stereochemistry effect of tetralin ring was probed, and (?)-(R)-2-amino-2-((S)-6-octyl-1,2,3,4-tetrahydronaphthalen-2-yl)propan-1-ol was identified as a good SphK2 substrate and potent S1P1 agonist with good oral bioavailability. 相似文献
927.
Lin He Fan He Huichang Bi Jiankang Li Su Zeng Hai-Bin Luo Min Huang 《Bioorganic & medicinal chemistry letters》2010,20(20):6008-6012
Our kinetics studies demonstrated that the nature product chrysin exhibited a high inhibitory affinity of 54 nM towards human cytochrome P450 1A2 and was comparable to α-naphthoflavone (49 nM), whereas it represented a moderate affinity of 5225 nM against human cytochrome P450 2C9. However, it remains unclear how this inhibitor selectively binds 1A2. To better understand the isoform selectivity of chrysin, molecular docking and molecular dynamics simulations were performed. Chrysin formed a strong H-bond with Asp313 of 1A2. The stacking interactions with Phe226 also contributed to its tight binding to 1A2. The larger and much more open active site architectures of 2C9 may explain the weaker inhibitory affinity of chrysin towards 2C9. The predicted binding free energies suggest that chrysin preferred 1A2 (ΔGbind, pred = ?23.11 kcal/mol) to 2C9 (?20.41 kcal/mol). Additionally, the present work revealed that 7-hydroxy-flavone bound to 1A2 in a similar pattern as chrysin and represented a slightly less negative predicted binding free energy, which was further validated by our kinetics analysis (IC50 = 240 nM). Results of the study can provide insight for designing novel isoform-selective 1A2 inhibitors. 相似文献
928.
一种定量检测人血清高敏C反应蛋白的化学发光免疫方法 总被引:2,自引:0,他引:2
旨在建立一种可定量检测人血清高敏CRP的化学发光检测方法 (High-sensitivity C-reactive protein quantifiable chemiluminescent immunoassay,hs-CRP CLIA)。首先利用亲和层析和离子交换层析技术从肝硬化病人腹水中纯化出高纯度的天然CRP作为免疫原制备了22株CRP单克隆抗体 (单抗),其中13株单抗在磷酸胆碱配体捕获ELISA中呈阳性,然后利用方正滴定法筛选出单抗10C5和10C11建立了hs-CRP CLIA。试剂盒评估结果显示:该方法对血清中干扰物质IgG、血红蛋白、甘油三酯等无非特异性反应;该方法检测灵敏度高,在0.04~20.38 mg/L范围内定量检测人血清CRP标准品呈良好线性关系 (R2>0.993);该方法准确性高、可重复性好,平均回收率为99%,批内差为4.2%~5.8%,批间差为9.0%~11.5%;该方法与进口商品化高敏CRP ELISA试剂盒平行比较检测90份血清标本,结果显示两者有良好的可比性 (r=0.968)。综上,建立的hs-CRP CLIA是一种准确、可靠、可定量的高灵敏C反应蛋白检测方法,该方法的临床应用,有利于改善我国心脏病风险评估及肠炎性疾病预后判断。 相似文献
929.
SHP2是一种非受体型蛋白酪氨酸磷酸酶,其介导的信号转导异常与多种疾病包括肿瘤的发生和发展密切相关,对SHP2的深入研究有助于对其作用机制的阐明以及潜在药物学靶点的发现。本文简要介绍了SHP2的结构、功能及其介导的Ras/ERK信号通路,并着重阐述了SHP2与乳腺癌发展的关系。 相似文献
930.