Isolation of viral coat protein mutants with altered assembly and aggregation properties

A method was developed to screen bacteria for synthesis of mutant proteins with altered assembly and solubility properties using bacteriophage MS2 coat protein as a model self-associating protein. Colonies expressing coat protein from a plasmid were covered with an agarose overlay under conditions that caused the lysis of some of the cells in each colony. The proteins thus liberated diffused through the overlay at rates depending on their molecular sizes. After transfer of the proteins to a nitrocellulose membrane, probing with coat protein-specific antiserum revealed spots whose sizes and intensities were related to the aggregation state of coat protein. The method was employed in the isolation of assembly defective mutants and to find soluble variants of an aggregation-prone coat protein mutant.     

Determination of 8-oxoguanine in human plasma and urine by high-performance liquid chromatography with electrochemical detection

A highly sensitive and selective method for determining 8-oxoguanine in plasma and urine was developed by high-performance liquid chromatography with electrochemical detection. The compound was separated by gradient elution on a C₁₈ reversed-phase column with a mobile phase of acetonitrile and 0.1 M sodium acetate, pH 5.2. 8-Hydroxy-2′-deoxyguanosine was used as internal standard. 8-Oxoguanine was detected electrochemically by setting the potential to +300 mV vs. Pd reference. The sensitivity of the assay was 22 ng/ml with a signal-to-noise ratio of 7:1. The within-day relative standard deviations for 8-oxoguanine quality control samples with concentrations of 3340, 1340 and 84 ng/ml were 3.6, 4.3 and 5.7% for plasma, and 4.1, 4.6 and 6.2% for urine, respectively. The day-to-day relative standard deviations for the same samples were 3.8, 6.8 and 7.1% for plasma, and 3.9, 7.0 and 7.9% for urine, respectively. The method is designed to study the pharmacokinetics and metabolic fate of O⁶-benzylguanine in a phase I clinical trial. Previously, O⁶-benzyl-8-oxoguanine was identified as the primary metabolite of O⁶-benzylguanine in humans. We now demonstrate that 8-oxoguanine is a further metabolite of O⁶-benzylguanine.     

A neural-network system for control of eye movements: basic mechanisms

This paper presents a neural-network-based system that can generate and control movements of the eyes. It was inspired by a number of experimental observations on the saccadic and gaze systems of monkeys and cats. Because of the generality of the approach undertaken, the system can be regarded as a demonstration of how parallel distributed processing principles, namely learning and attractor dynamics, can be integrated with experimental findings, as well as a biologically inspired controller for a dexterous robotic orientation device. The system is composed of three parts: a dynamic motor map, a push-pull circuitry, and a plant. The dynamics of the motor map is generated by a multi-layer network that was trained to compute a bidimensional temporal-spatial transformation. Simulation results indicate (1) that the system is able to reproduce some of the properties observed in the biological system at the neural and movement levels and (2) that the dynamics of the motor map remains stereotyped even when the motor map is subject to abnormal stimulation patterns. The latter result emphasizes the role of the topographic projection that connects the motor map to the push-pull circuitry in determining the features of the resulting movements.     

[D丙~6,脯~9乙基胺]-促黄体素释放激素LH-RHA对妊娠兔子宫内膜多聚核糖体mRNA的作用

本实验制备了非孕兔、孕兔和绐孕兔注射高剂量[D丙‘,脯’乙基胺]-促黄体素释放激素(LH-RH A)不同天数的子宫内膜多聚核糖体,并从多聚核糖体提取mRNA,在网织红细胞无细胞翻译系统中测定了活性。结果指出用LH-RH A处理后多聚核糖体mRNA量减少,其翻译活性降低,在体内实验中核糖体mRNA诱导兔子宫分秘蛋白的合成也受到抑制,特别是分子量大约为22,000和69,000左右的分泌蛋白合成受到明显抑制。     

云南所麻蝇属一新种记述：双翅目：麻蝇科

作者在整理1985年采集的麻蝇科标本中,发现所麻蝇属(SarcosolomoniaBaranov)1新种。模式标本分别保存于云南省卫生防疫站和军事医学科学院微生物流行病研究所。     

横断山齿突蟾属一新种(两栖纲:锄足蟾科)

1982年在横断山区考察期间,发现四川木里截族自治县的齿突蟾Scutiger标本在第二性征、趾蹼等特征与已知的各种齿突蟾均不相同,描述为新种木里齿突蟾Scutiger muliensis。     

齿突蟾属某些种的多态现象

本文报道某些锄足蟾科Pelobatidae动物的多态现象。讨论了同域或不同域的四种齿突蟾Scuti-ger,即刺胸齿突蟾S. mammatus(Guenther)、胸腺齿突蟾S. glandulatus(Liu)、木里齿突蟾S. mulicnsis Fei et Ye和皱纹齿突蟾S. ruginosus Zhao et jiang的皮肤瘰疣、第二性征等性状;用薄层等电聚焦电泳方法分析了同域三种齿突蟾的晶体蛋白。结果表明:前三种是有效种;后一种,即皱纹齿突蟾分别是前三种的多态性变体;这些变体以相同性状(即皮肤多瘭疣)同时表现在三个种中的现象,属于平行多态现象。     

环状RNA在肝细胞癌中的作用及机制

肝细胞癌（hepatocellular carcinoma,HCC）治疗困难、预后很差,是肿瘤相关死亡中的第4大癌症,严重危害人类生命健康,但其具体发病机制却仍未完全阐明。因此,探索能调控肝细胞癌发生发展,作为肝细胞癌的诊断标志物或能预测患者预后的关键分子仍十分必要。环状RNA是前体mRNA通过反向剪接产生的由3′, 5′ 磷酸二酯键首尾连接形成的共价闭合环状结构,主要有外显子circRNA（exonic circRNA,ecircRNA）、环状内含子RNA（circular intronic RNA,ciRNA）及外显子 内含子circRNA（exon-intron circRNA,EIciRNA）三大类。由于环状RNA具有普遍性、高度保守性和稳定性,其可以参与多种癌症的发生发展过程,并且可作为肿瘤的早期诊断标志物及预后因子,因此,这是一类新型且非常有潜力应用于临床诊治各阶段的分子。近年来,有大量关于环状RNA与肝细胞癌的研究。这些研究表明,环状RNA在肝细胞癌发生发展进程中发挥的作用十分重要,并且其机制多样。因此,本文主要关注环状RNA在肝细胞癌中的最新进展,总结不同环状RNA分子对于肝细胞癌细胞恶性表型、肿瘤干细胞及肿瘤微环境中免疫细胞的作用,以及其在肝细胞癌临床转移、分期、诊断、预后等各阶段中发挥的功能及其具体作用机制。此外,本文还提出了目前研究中存在的一些问题和不足,以期为未来的研究提供一些新的思路及策略。     

长非编码RNA PVT1与消化系统肿瘤

长非编码RNA（long non-coding RNAs, lncRNAs）在肿瘤发生、发展进程中承担重要角色,是近年来的研究热点之一。大量研究表明,浆细胞瘤变异易位基因1（plasmacytoma variant translocation 1, PVT1）可通过多种分子机制参与调控消化系统肿瘤的增殖凋亡、迁移侵袭、细胞自噬、血管生成、多药耐药及肿瘤代谢等过程,从而发挥致癌作用。本文主要就PVT1在消化系统肿瘤中的表达水平变化,及其与临床病理特征和预后的关系,以及PVT1对消化系统肿瘤的致癌作用机制和多药耐药机制等研究进展作一综述。