Solid-state NMR as a method to reveal structure and membrane-interaction of amyloidogenic proteins and peptides

It is important to understand the Amyloid fibril formation in view of numerous medical and biochemical aspects. Structural determination of amyloid fibril has been extensively studied using electron microscopy. Subsequently, solid state NMR spectroscopy has been realized to be the most important means to determine not only microscopic molecular structure but also macroscopic molecular packing. Molecular structure of amyloid fibril was first predicted to be parallel β-sheet structure, and subsequently, was further refined for Aβ(1-40) to be cross β-sheet with double layered in register parallel β-sheet structure by using solid state NMR spectroscopy. On the other hand, anti-parallel β-sheet structure has been reported to short fragments of Aβ-amyloid and other amyloid forming peptides. Kinetic study of amyloid fibril formation has been studied using a variety of methods, and two-step autocatalytic reaction mechanism used to explain fibril formation. Recently, stable intermediates or proto-fibrils have been observed by electron microscope (EM) images. Some of the intermediates have the same microscopic structure as the matured fibril and subsequently change to matured fibrils. Another important study on amyloid fibril formation is determination of the interaction with lipid membranes, since amyloid peptide are cleaved from amyloid precursor proteins in the membrane interface, and it is reported that amyloid lipid interaction is related to the cytotoxicity. Finally it is discussed how amyloid fibril formation can be inhibited. Firstly, properly designed compounds are reported to have inhibition ability of amyloid fibril formation by interacting with amyloid peptide. Secondly, it is revealed that site directed mutation can inhibit amyloid fibril formation. These inhibitors were developed by knowing the fibril structure determined by solid state NMR.     

麻疹、腮腺炎二联活疫苗的研制

用于生产麻诊活疫苗的“沪191”毒株和由武汉生物制品研究所引进的腮腺炎疫苗“Wms4”毒株生产各自的病毒原液,全面检定合格后,对麻疹与腮腺炎两种病毒原液进行配比试验、热稳定性试验等,最终选定联合疫苗中麻疹与腮腺炎病毒CCID50之比1：30,试制出二批麻－腮二联活疫苗,经全面检定,完全符现行规程要求,目前正在I期临床研究。     

19个枇杷杂交新品种(系)的SSR鉴定和指纹图谱构建

为探究枇杷(Eriobotryajaponica)杂交品种真实性和DNA指纹图谱,对新育成的19个枇杷杂交品种(系)进行SSR标记鉴定分析。结果表明,从已发表的89对SSR引物中筛选出扩增条带清晰稳定的多态性引物19对,在24份枇杷材料中共扩增到83条带,每对引物平均扩增4.37条,PIC值为0.234～0.983,平均为0.764。经12对具有父本特征带多态性引物鉴定, 19个杂交新品种(系)全部为真杂种,真杂种率为100%。UPGMA聚类分析表明,19个杂交新品种(系)的遗传相似系数为0.728～0.969,与杂交亲本‘新白2号’和‘贵妃’聚为同一个大类,并可细分为4个亚类,红肉与白肉的枇杷品种(系)间无明显划分。同时利用8对多态性SSR引物组合,构建了19个枇杷杂交新品种(系)的分子指纹图谱。这为枇杷品种鉴定、新品种权保护和杂交育种提供重要参考依据。     

Augmented cross-sectional studies with abbreviated follow-up for estimating HIV incidence

Cross-sectional HIV incidence estimation based on a sensitive and less-sensitive test offers great advantages over the traditional cohort study. However, its use has been limited due to concerns about the false negative rate of the less-sensitive test, reflecting the phenomenon that some subjects may remain negative permanently on the less-sensitive test. Wang and Lagakos (2010, Biometrics 66, 864-874) propose an augmented cross-sectional design that provides one way to estimate the size of the infected population who remain negative permanently and subsequently incorporate this information in the cross-sectional incidence estimator. In an augmented cross-sectional study, subjects who test negative on the less-sensitive test in the cross-sectional survey are followed forward for transition into the nonrecent state, at which time they would test positive on the less-sensitive test. However, considerable uncertainty exists regarding the appropriate length of follow-up and the size of the infected population who remain nonreactive permanently to the less-sensitive test. In this article, we assess the impact of varying follow-up time on the resulting incidence estimators from an augmented cross-sectional study, evaluate the robustness of cross-sectional estimators to assumptions about the existence and the size of the subpopulation who will remain negative permanently, and propose a new estimator based on abbreviated follow-up time (AF). Compared to the original estimator from an augmented cross-sectional study, the AF estimator allows shorter follow-up time and does not require estimation of the mean window period, defined as the average time between detectability of HIV infection with the sensitive and less-sensitive tests. It is shown to perform well in a wide range of settings. We discuss when the AF estimator would be expected to perform well and offer design considerations for an augmented cross-sectional study with abbreviated follow-up.     

Isolation and characterization of microsatellite loci in the red mangrove Rhizophora mangle (Rhizophoraceae) and its related species

Fourteen microsatellite markers were isolated from the red mangrove Rhizophora mangle (Rhizophoraceae), a widely distributed mangrove plant in the New World and West Africa. The range of expected heterozygosity of these markers was 0.000–0.672 in the two populations of R. mangle. Cross-species testing was examined for five other species of Rhizophora, and Kandelia candel and Bruguiera gymnorrhiza. All 14 markers could be amplified in R. samoensis, thirteen in R. racemosa, and six markers in all other species of Rhizophora. Our findings greatly increase the utility of these markers.     

大豆不同亲本类型F2主要性状遗传参数分析

对大豆3个不同亲本类型的杂交组合F2群体主要性状遗传变异系数、遗传力和遗传进度进行了估算分析,结果表明这些遗传参数因性状或亲本类型的不同而有明显差异.含有野生亲缘关系的组合,类型间、性状间F2遗传力有较大差异,性状变异幅度增大,相对遗传进度也较大,从而有较广泛的选择基础.     

Regulatory properties of the nitrogenase fromRhodopseudomonas palustris

Ammonium salts, glutamine, asparagine, and urea cause an immediate inactivation (switch-off) of light-dependent acetylene reduction in intact cells of the photosynthetic bacteriumRhodopseudomonas palustris. This effect is reversible showing the same kinetic pattern of inactivation and reactivation with all effector compounds. Its duration depends on the amount of effector added to the cells. Both nitrogenase components are found catalytically active in a cell-free preparation after enzyme switch-off in vivo. Involvement of the ammonia assimilating system in this regulatory mechanism is indicated by the following observations: ammonia uptake during the switch-off period, resumption of acetylene reduction after disappearance of ammonia from the outer medium, and persistence of enzyme switch-off with dihydrogen and thiosulfate as electron donors in the absence of an additional carbon source. Nitrogenase activity in crude extracts is non-linear with time and is stimulated by manganese ions. After resolution of nitrogenase into its MoFe-protein and Fe-protein these properties are lost, indicating the presence of an activating factor. Nitrogenase ofR. palustris cross reacts reciprocally with the complementary proteins ofAzotobacter vinelandii, but not with those ofClostridium pasteurianum.Abbreviations CCCP m-chlorocarbonyl cyanide phenyl hydrazone - DNP 2,4-dinitrophenol - EPR electron paramagnetic resonance - HEPES N-2-hydroxyethylpiperazine--2-ethane sulfonic acid - NOQNO 2-n-nonyl-4-hydroxyquinoline-N-oxide - TES N-tris[hydroxymethyl]methyl-2-aminoethane sulfonic acid     

Cross bridge slippage in skinned frog muscle fibres

Mechanically skinned single fibres of the semitendinosus muscles of Rana esculenta were investigated at ca. 4 C. The fibres were activated by a Ca²⁺ jump technique, which allowed the development of a steady isometric tension within several seconds of entering a calcium rich solution at 4 C. Sequences of length changes of different duration and amplitude were applied to the fibre. It could be demonstrated that the fibre behaved as a Hookean spring in the case of small amplitude length changes (up to 0.5% L₀, ramp duration 0.5 ms) and that a sequence of length changes induced reversible changes in fibre state. In contrast, large stretches (> 1% L₀) induced a muscle give if the stretch were not immediately preceded by a release. The data was interpreted on the basis of a strain induced detachment of cross bridges in combination with a rapid reattachment of presumably the same cross bridges in a discharged position. The rates of strain induced detachment and reattachment depended on the stretch amplitude. At amplitudes exceeding 2% L₀ the rates were estimated to be at least several thousands per second.