树鼩的骨元和骨细胞穴微观结构超微影像的定性比较

近年来,由于树鼩与灵长类动物的亲缘关系,它们引起了人类发展和疾病研究的兴趣。在这项对树鼩,鼠,狗,狒狒和人类的骨骼超微形态的比较研究中,我们定性分析了骨骼的微观结构和形态,以评估树鼩对人类的亲近程度。在3只成年雄性树鼩 (滇西亚种) (Tupaia belangeri chinensis）的股骨中,使用荧光素异硫氰酸盐样品制备和染色共聚焦成像研究了皮质骨的骨元结构,并使用酸蚀刻SEM观察了骨细胞穴的形态。总体而言,树鼩中骨样形成物的密度和结构以及骨细胞穴的形态更像鼠, 与人类,狗和狒狒都明显不同。这些发现表明,尽管树鼩在系统发育上比鼠更接近人类,但它们的骨骼超微形态仍与鼠接近。这是除狗和狒狒之外,第一次对树鼩的骨元和骨细胞穴进行超微影像的研究。这个比较研究的结果丰富了我们对早期灵长类动物骨骼发育,适应性和进化的理解。未来有必要进行进一步的定量比较研究来表征树鼩骨骼的微观形态。     

Inhibition of insulin amyloid formation by small stress molecules

Amyloidogenic proteins undergo an alternative folding pathway under stressful conditions leading to formation of fibrils having cross beta-sheet structure, which is the hallmark of many neurodegenerative diseases. As a means of surviving against external stress, on the other hand, many microorganisms accumulate small stress molecules to prevent abnormal protein folding and to contribute to protein stability, which hints at the efficacy of the solutes against amyloid formation. The current work demonstrates the effectiveness of small stress molecules such as ectoine, betaine, trehalose, and citrulline on inhibition of insulin amyloid formation in vitro. The inhibitory effects were analyzed by thioflavin T-induced fluorescence, circular dichroism, and atomic force microscopy. This report suggests that naturally occurring small molecules may serve a function that is typically fulfilled by protein chaperones, and it provides a hint for designing inhibitors against amyloid formation associated with neurodegenerative disorders.     

The search for new fragrance ingredients for functional perfumery

Functional perfumery is an integral part of the fragrance business. It demands that the ingredients chosen for compounding withstand the aggressive nature of some of the bases used for soaps, detergents, softeners, bleach, and personal-care products. The synthetic efforts in this area reported in this short personal account, presented in a talk at the RSC/SCI conference Flavours & Fragrances 2004 (Manchester), have resulted in the discovery of the two new proprietary molecules Fleuranil (5/6) and Khusinil (7), which fulfill the criteria of functional perfumery. The structure-odor relationships of several analogs of Fleuranil and Khusinil prepared in the course of these investigations are also presented.     

Simultaneously estimating food web connectance and structure with uncertainty

1. Food web models explain and predict the trophic interactions in a food web, and they can infer missing interactions among the organisms. The allometric diet breadth model (ADBM) is a food web model based on the foraging theory. In the ADBM, the foraging parameters are allometrically scaled to body sizes of predators and prey. In Petchey et al. (Proceedings of the National Academy of Sciences, 2008; 105: 4191), the parameterization of the ADBM had two limitations: (a) the model parameters were point estimates and (b) food web connectance was not estimated.
2. The novelty of our current approach is: (a) We consider multiple predictions from the ADBM by parameterizing it with approximate Bayesian computation, to estimate parameter distributions and not point estimates. (b) Connectance emerges from the parameterization, by measuring model fit using the true skill statistic, which takes into account prediction of both the presences and absences of links.
3. We fit the ADBM using approximate Bayesian computation to 12 observed food webs from a wide variety of ecosystems. Estimated connectance was consistently greater than previously found. In some of the food webs, considerable variation in estimated parameter distributions occurred and resulted in considerable variation (i.e., uncertainty) in predicted food web structure.
4. These results lend weight to the possibility that the observed food web data is missing some trophic links that do actually occur. It also seems likely that the ADBM likely predicts some links that do not exist. The latter could be addressed by accounting in the ADBM for additional traits other than body size. Further work could also address the significance of uncertainty in parameter estimates for predicted food web responses to environmental change.

     

Biocompatible nanoparticles trigger rapid bacteria clustering

This study reveals an exciting phenomenon of stimulated bacteria clustering. Rapid aggregation and microbial arrest are shown to occur in Escherichia coli solutions of neutral pH when chitosan nanoparticles with positive zeta potential are added. Because chitosan nanoparticles can easily be dispersed in aqueous buffers, the rapid clustering phenomenon requires only minuscule nanoparticle concentrations and will be critical in developing new methods for extricating bacterial pathogens. This work establishes the dominant role of electrostatic attraction in bacteria‐nanoparticle interactions by varying the nanoparticle zeta potential from highly positive to strongly negative values, and by exploring concentration effects. For strongly negative nanoparticles, no clusters form, while aggregates are small and loose at intermediate conditions. In addition, optical density measurements indicate that over 90% of the suspended bacteria flocculate within seconds of being mixed with chitosan nanoparticles of a highly positive surface charge. Finally, the nanoparticles are significantly more efficient as a clustering agent compared to an equal mass of molecular chitosan in solution, as the bacteria‐nanoparticle clusters formed are substantially larger. The bacteria‐nanoparticle aggregation effect demonstrated here promises a rapid separation method for aiding pathogen detection and for flocculation of bacteria in fermentation processes. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Isolating Influenza RNA from Clinical Samples Using Microfluidic Oil-Water Interfaces

The effective and robust separation of biomolecules of interest from patient samples is an essential step in diagnostic applications. We present a platform for the fast extraction of nucleic acids from clinical specimens utilizing paramagnetic PMPs, an oil-water interface, a small permanent magnet and a microfluidic channel to separate and purify captured nucleic acids from lysate in less than one minute, circumventing the need for multiple washing steps and greatly simplifying and expediting the purification procedure. Our device was able to isolate influenza RNA from clinical nasopharyngeal swab samples with high efficiency when compared to the Ambion® MagMAX^TM Viral RNA Isolation Kit, sufficiently separating nucleic acid analytes from PCR-inhibiting contaminants within the lysate while also critically maintaining high integrity of the viral genome. We find that this design has great potential for rapid, efficient and sensitive nucleic acid separation from patient sample.