金缕梅科银缕梅属与帕罗堤属的亲缘关系——核糖体DNA ITS序列证据

本文对金缕梅科弗特吉族(Molinadendron和Matudaea除外)的细胞核核糖体DNA ITS片段进行了序列分析,在此基础上对该族的演化关系、尤其是中国特有属银缕梅属的系统位置进行了最简约分支分析。基本结果如下：其一,蚊母族和狭义的弗特吉族均不形成自己的单系分支,因此,支持Endress的处理,即合并两族为广义的弗特吉族;其二,银缕梅属同帕罗堤属有着密切的亲缘关系,支持形态学和解剖学结论;其三,根据该片段核苷酸序列的演化速率推算出的银缕梅属和帕罗堤属间分化时间为晚中新世。此结论大致与化石记录相符。     

Uncialamycin as a novel payload for antibody drug conjugate (ADC) based targeted cancer therapy

Uncialamycin analogs were evaluated as potential cytotoxic agents in an antibody-drug conjugate (ADC) approach to treating human cancer. These analogs were synthesized using Hauser annulations of substituted phthalides as a key step. A highly potent uncialamycin analog 3c with a valine-citrulline dipeptide linker was conjugated to an anti-mesothelin monoclonal antibody (mAb) through lysines to generate a meso-13 conjugate. This conjugate demonstrated subnanomolar potency (IC50?=?0.88?nM, H226 cell line) in in vitro cytotoxicity experiments with good immunological specificity to mesothelin-positive lung cancer cell lines. The potency and mechanism of action of this uncialamycin class of enediyne antitumor antibiotics make them attractive payloads in ADC-based cancer therapy.     

ELK-1/JNK/c-Fos对左归降糖解郁方(ZGJTJYF)体外培养的模拟糖尿病并发抑郁症(DD)大鼠海马神经元凋亡中的作用

目的:研究信号通路ELK-1/JNK/c-Fos在左归降糖解郁方(ZGJTJYF)对模拟糖尿病并发抑郁症(DD)环境下抗海马神经元凋亡中的作用。方法:原代培养海马神经元,加入高糖(150 mmol/L)+皮质酮(200μmol/L),构建DD体外细胞模型;将培养的海马神经元细胞随机分为5组:空白血清组、正常组、左归降糖解郁方含药血清组、阳性药(二甲双胍+氟西汀)含药血清组和模型组(每组3个复孔)。模型组和正常组给予等量培养液,其余组加入相应体积分数10%的相应血清,均干预18 h。分别采用Hoechst染色、高内涵细胞成像分析技术和RT-PCR技术分别检测海马神经元凋亡情况及检测凋亡相关ELK-1、JNK和c-Fos蛋白和基因的表达。结果:与空白组比较,模型组细胞凋亡明显,其海马神经元凋亡数量明显增多,ELK-1、JNK和c-Fos的mRNA及蛋白表达水平均显著升高(P<0.05);与模型组比较,左归降糖解郁方含药血清组和阳性药含药血清组大鼠海马神经元可见局部亮点明显减少,凋亡细胞数显著减少,ELK-1、JNK和c-Fos蛋白及mRNA表达均明显下调(P<0.05),且神经网络及树突连接情况得到明显改善。结论:左归降糖解郁方可以减低DD环境下海马神经元中Elk-1、JNK、c-fos表达而起到抗凋亡的效果。     

环状RNA在胃癌中的研究现状与策略

环状RNA (circRNA)是一种共价闭合的非编码RNA,可以调节真核生物中的基因表达.最近应用高通量RNA测序和生物信息学方法揭示人类细胞中存在大量circRNA.许多circRNA具有一定的组织和时序特异性,且与生理发育和各种肿瘤等疾病密切相关. circRNA被证明在细胞质中富集和稳定,表明其具有作为肿瘤生物标志物的潜力.胃癌(gastric carcinoma,GC)是一种常见的恶性肿瘤,在全球癌症相关死亡原因中排第3位.尽管该疾病在诊断和治疗方面取得了许多进展,但GC患者的预后仍然很差,大多数国家的5年总生存率低于30%.因此,寻找能调节GC发生发展和评估预后的新分子机制和治疗靶标至关重要.近年来circRNA在胃癌中的研究不断增多,其在胃癌的发生发展、诊断、治疗及预后过程中扮演重要角色.本文就circRNA产生机制及一般特征、生物学功能、在胃癌中的研究进展及研究中存在的问题作一综述.     

The use of spun columns in the purification of double-stranded cDNA appropriate for tailing

A reliable estimation of the efficiency of adding homopolymeric tails to double-stranded cDNA molecules by terminal deoxynucleotidyl transferase is extremely important in the construction of cDNA libraries. Appreciable differences in transformation efficiency result when the homopolymer tails to be annealed are of inadequate length. We report here that the use of a Sephadex G-50 spun column to remove oligo(dT)12-18 frequently coprecipitating in ethanol with the cDNA results in a more dependable estimation of tail lengths.     

The two binding sites for DCMU in Photosystem II

Measurements on the fluorescence induction of Triton X-100 extracted Photosystem II (PSII) particles confirmed the existence of the two sites of inhibition in PSII for the herbicide DCMU. The two sites were located on the reducing and oxidizing sides of PSII, respectively. The inhibition on the oxidizing side, unlike that on the reducing side which was of the "none or all" type, was found only to slow down the electron donation at low concentrations of DCMU. The results also suggested that the inhibitions of DCMU at these two sites were mutually exclusive, i.e., the binding on one site prevented the binding on the other site.     

Preparation and characterization of radioactive castanospermine

A procedure for the preparation of tritiated castanospermine is described. The tritiated alkaloid was shown to be chromatographically identical to the native material and exhibited the same inhibitory properties. Radiolabeled castanospermine tightly bound to purified intestinal sucrase. Following gel chromatography, each mole of enzyme was shown to have bound 1 mol of the radioactive alkaloid. Cultured MDCK cells were also shown to take up the labeled castanospermine. This compound should be a useful tool in the investigation of enzymes that are responsible for the processing of glycoprotein oligosaccharides.     

不同光照强度下植物电信号变化特征及其与空气负离子的关系

空气负离子(NAI)是衡量一个地区空气清洁度的重要指标,对人体的心理健康和生理机能具有重要的调节作用.植被光合过程中光电效应是NAI产生的重要来源和影响因素,但光电效应极其微弱而难以直接监测,而植物电信号是间接反映光电效应的重要指标,以往研究多侧重在不同森林群落中NAI的时空变化特征及其与气象因素的关系,目前关于NAI...     

荷叶铁线蕨自然居群的遗传多样性研究

荷叶铁线蕨(Adiantumreniformevar. sinense)为我国特有植物,具有重要的经济价值,目前仅分布于重庆的少数地区。近几十年来,由于过度开发,该种的分布范围日益缩小,已处于灭绝的边缘。本研究利用等位酶标记检测了荷叶铁线蕨 6个自然居群共 136个个体的遗传多样性,共检测到了 5个酶系统的 14个位点,获得了 7个多态位点。结果表明:与其他蕨类植物相比,荷叶铁线蕨居群内的遗传多样性水平比较低。平均每位点的有效等位基因数(Ae)为 1. 778,多态位点百分率(P)为 0. 441,期望杂合度(He)为 0. 199,观察杂合度 (Ho)为 0. 235。其居群间的遗传分化也很低,居群间的遗传变异仅占总变异的 1. 49%,而 98. 51%的变异存在于居群内部。采用Hardy Wein berg平衡和固定指数F对荷叶铁线蕨的居群遗传结构进行了分析,结果表明其种群可能是以配子体间异交为主的混合交配体系。导致荷叶铁线蕨濒危的主要原因是生境的破坏以及过度开采所导致的生境片断化使其居群变小、近交率加大、遗传变异趋低,降低了其生存以及进化的潜力。     

基于代谢通量分析的琥珀酸放线杆菌高产选育研究

在对产琥珀酸放线杆菌代谢分析的基础上选育出高产突变株对琥珀酸的工业生物转化有重要意义.在矩阵分析代谢通量基础上,围绕柔性节点下的副产物乙酸及乙醇的降低分别实施软X诱变及定点突变选育,并对比分析了突变株与出发株相关酶活及基因序列变化.针对出发株的流量分析显示产物琥珀酸的代谢通量为1.78(mmol/g/h),主要副产物乙酸与乙醇的代谢通量分别为(0.60mmol/g/h)和(1.04 mmol/g/h),并发现乙醇代谢加剧了琥珀酸合成中的H电子供体的不足;筛选出的氟乙酸抗性突变株S.JST1的乙酸代谢通量降低了96%,为0.024(mmol/g/h),酶活检测表明磷酸乙酰转移酶(Pta)的酶比活力从602降低到74,进一步的序列对比分析发现pta突变基因中产生了一个突变位点:adh定点复合突变株S.JST2的乙醇代谢通量降低了98%,为0.020(mmol/g/h),酶活检测表明Adh的酶比活力从585降低到62.最终突变株S.JST2琥珀酸累积产量达65.7 g/L.围绕产琥珀酸放线杆菌Pta及Adh酶活的降低实施定向选育,在降低副产物流量的同时,有助于改善细胞H供体代谢平衡进而提高琥珀酸的流量.所获突变株具有工业应用潜力.