Solution NMR views of dynamical ordering of biomacromolecules

Background

To understand the mechanisms related to the ‘dynamical ordering’ of macromolecules and biological systems, it is crucial to monitor, in detail, molecular interactions and their dynamics across multiple timescales. Solution nuclear magnetic resonance (NMR) spectroscopy is an ideal tool that can investigate biophysical events at the atomic level, in near-physiological buffer solutions, or even inside cells.

江西省九连山自然保护区的植被

1． 九连山自然保护区位于我国南部的南岭山地东段,处于江西南部,与广东边境相连,北纬24˚31′一24˚39′,东经114˚27′一114˚29′,面积约2000公顷。2．自然保护区内动植物种类极为丰富,其中高等植物1200种以上,约有206科;苔藓植物约30种,蕨类约62种,种子植物1100种以上。脊椎动物100多种。3．动植物区系起源较古老,有许多古代的科属,包括很多残遗种和稀有种。又是我国著名的单种属：观光木属和半枫荷属的家乡。有许多稀有的珍贵动物如：云豹、金猫、豹、华南虎、獐、水鹿、鬣羚、大灵猫、穿山甲、水獭、白鹇、平胸龟等。动物区系上,属于东洋界的华中区。4．自然保护区植被主要有四个群系纲;Ⅰ．常绿阔叶林;Ⅱ．针叶林;Ⅲ．山地草甸;Ⅳ．山地苔藓、矮林;14个群系,约19个群丛。顶极植被为常绿阔叶林。     

Gold nanoparticle-based colorimetric detection of kanamycin using a DNA aptamer

A selective kanamycin-binding single-strand DNA (ssDNA) aptamer (TGGGGGTTGAGGCTAAGCCGA) was discovered through in vitro selection using affinity chromatography with kanamycin-immobilized sepharose beads. The selected aptamer has a high affinity for kanamycin and also for kanamycin derivatives such as kanamycin B and tobramycin. The dissociation constants (K_d [kanamycin] = 78.8 nM, K_d [kanamycin B] = 84.5 nM, and K_d [tobramycin] = 103 nM) of the new aptamer were determined by fluorescence intensity analysis using 5′-fluorescein amidite (FAM) modification. Using this aptamer, kanamycin was detected down to 25 nM by the gold nanoparticle-based colorimetric method. Because the designed colorimetric method is simple, easy, and visible to the naked eye, it has advantages that make it useful for the detection of kanamycin. Furthermore, the selected new aptamer has many potential applications as a bioprobe for the detection of kanamycin, kanamycin B, and tobramycin in pharmaceutical preparations and food products.     

迁人江淮稻区褐稻虱生物型跟踪监测及分析

该文对近年来褐稻虱迁入虫源的性质进行了探讨,结果表明迁入的虫源在鉴别品种Mudgo上的致害力,生存率、取食量和原始的种群生物型I没有明显的差别;两者在酯酶同工酶谱带数目和RF值也没有差异。迁入的虫源在田间抗性品种上明显表现虫量少。因此,迁入江淮稻区虫源仍是种群生物型I。人工在Mudgo上诱导产生的生物型1再回到感性品种上连续饲养8代,其对Mudgo的致害性降为1.O级,表明了褐稻虱生物型的不稳定性。     

The complete structure of the chloroplast 70S ribosome in complex with translation factor pY

Chloroplasts are cellular organelles of plants and algae that are responsible for energy conversion and carbon fixation by the photosynthetic reaction. As a consequence of their endosymbiotic origin, they still contain their own genome and the machinery for protein biosynthesis. Here, we present the atomic structure of the chloroplast 70S ribosome prepared from spinach leaves and resolved by cryo‐EM at 3.4 Å resolution. The complete structure reveals the features of the 4.5S rRNA, which probably evolved by the fragmentation of the 23S rRNA, and all five plastid‐specific ribosomal proteins. These proteins, required for proper assembly and function of the chloroplast translation machinery, bind and stabilize rRNA including regions that only exist in the chloroplast ribosome. Furthermore, the structure reveals plastid‐specific extensions of ribosomal proteins that extensively remodel the mRNA entry and exit site on the small subunit as well as the polypeptide tunnel exit and the putative binding site of the signal recognition particle on the large subunit. The translation factor pY, involved in light‐ and temperature‐dependent control of protein synthesis, is bound to the mRNA channel of the small subunit and interacts with 16S rRNA nucleotides at the A‐site and P‐site, where it protects the decoding centre and inhibits translation by preventing tRNA binding. The small subunit is locked by pY in a non‐rotated state, in which the intersubunit bridges to the large subunit are stabilized.     

Effect of Carotid Artery Stenting on Cognitive Function in Patients with Internal Carotid Artery Stenosis and Cerebral Lacunar Infarction: A 3-Year Follow-Up Study in China

Background and Objectives

Carotid artery stenting (CAS) is an important therapeutic strategy for patients with carotid artery stenosis. However, the potential influence of CAS on cognitive function in patients with carotid artery stenosis and cerebral lacunar infarction has not been determined. This study investigated changes in cognitive function associated with CAS and the factors related to these changes.

Methods

This prospective cohort study comprised 579 Chinese patients with cerebral lacunar infarction and carotid artery stenosis for whom CAS was indicated, and a matched control group of 552 healthy individuals. Cognitive function before CAS and at scheduled intervals from 6 months to 3 years was assessed with instruments that included the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scale. Potential factors that might affect cognitive function were analyzed via logistic regression.

Results

The MMSE and MoCA scores of the patients before CAS were significantly lower than that of the control subjects. These scores were significantly higher 6 months after CAS and sustained or increased throughout the 3-year follow-up. Also significantly improved after CAS from baseline were scores for an alternating trail test, cube copying, clock-drawing, attention, and delayed recall in an auditory-verbal learning test. Logistic regression analyses showed that age greater than 65 y, little education, diabetes, and hypertension were independent risk factors for deteriorated MoCA scores 3 years after CAS.

Conclusion

CAS was associated with significantly improved cognitive function in cerebral lacunar infarction patients with severe stenosis.     

HAC stability in murine cells is influenced by nuclear localization and chromatin organization

Background  

Human artificial chromosomes (HAC) are small functional extrachromosomal elements, which segregate correctly during each cell division. In human cells, they are mitotically stable, however when the HAC are transferred to murine cells they show an increased and variable rate of loss. In some cell lines the HAC are lost over a short period of time, while in others the HAC become stable without acquiring murine DNA.