Protein evolution: intrinsic preferences in peptide bond formation: a computational and experimental analysis

Two possibilities exist for the evolution of individual enzymes/proteins from a milieu of amino acids, one based on preference and selectivity and the other on the basis of random events. Logic is overwhelmingly in favour of the former. By protein data base analysis and experiments, we have provided data to show the manifestation of two types of preferences, namely, the choice of the neighbour and its acceptance from the amino end (left) or the carboxyl end (right). The study tends to show that if the 20 proteinous amino acids were made to combine in water, the resulting profile would be nonrandom. Such selectivity could be a factor in protein evolution. Dedicated to the memory of Darshan Ranganathan.     

A bioresorbable, polylactide reservoir for diffusional and osmotically controlled drug delivery

The purpose of this study was to design and characterize a zero-order bioresorbable reservoir delivery system (BRDS) for diffusional or osmotically controlled delivery of model drugs including macromolecules. The BRDS was manufactured by casting hollow cylindrical poly (lactic acid) (PLA): polyethylene glycol (PEG) membranes (10 x 1.6 mm) on a stainless steel mold. Physical properties of the PLA:PEG membranes were characterized by solid-state thermal analysis. After filling with drug (5 fluorouracil [5FU] or fluorescein isothiocyanate [FITC]-dextran:mannitol, 5:95 wt/wt mixture) and sealing with viscous PLA solution, cumulative in vitro dissolution studies were performed and drug release monitored by ultraviolet (UV) or florescence spectroscopy. Statistical analysis was performed using Minitab (Version 12). Differential scanning calorimetry thermograms of PLA:PEG membranes dried at 25 degrees C lacked the crystallization exotherms, dual endothermal melting peaks, and endothermal glass transition observed in PLA membranes dried at -25 degrees C. In vitro release studies demonstrated zero-order release of 5FU for up to 6 weeks from BRDS manufactured with 50% wt/wt PEG (drying temperature, 25 degrees C). The release of FITC dextrans of molecular weights 4400, 42 000, 148 000, and 464 000 followed zero-order kinetics that were independent of the dextran molecular weight. When monitored under different concentrations of urea in the dissolution medium, the release rate of FITC dextran 42 000 showed a linear correlation with the calculated osmotic gradient(DeltaPi). This study concludes that PEG inclusion at 25 degrees C enables manufacture of uniform, cylindrical PLA membranes of controlled permeability. The absence of molecular weight effects and a linear dependence of FITC-dextran release rate on DeltaPi confirm that the BRDS can be modified to release model macromolecules by an osmotically controlled mechanism.     

不同条件下荔枝多酚氧化酶活性的分析(英)

经硫酸铵盐析和ＳｅｐｈａｄｅｓＧ－１００,Ｑ－Ｓｅｐｈａｒｏｓｅ和ＰｈｅｎｙｌＳｅｐｈａｒｏｓｅ柱层析分别纯化后,得到了电泳均一的荔枝多酚氧化酶,荔枝多酚氧化酶在ＳＤＳ和ＣＡＴＢ存在下测得的酶活性略有降低,但在ＴｒｉｔｏｎＸ－１００下活性有所增加,丁酸等短链的脂肪酸对酶活性起抑制作用,而亚油酸等长链的不饱和脂肪酸则起促进作用,另外,荔枝多酚氧化酶活性还明显受ＦｅＳＯ４和ＳｎＣｌ２所抑制,但能补Ｃａ     

High-Andean vegetation and environmental gradients in northwestern Patagonia,Argentina

Abstract. We analysed the heterogeneity of high-elevation vegetation on three mountains along a west-east transect at 41 °S lat. in the Andes of northwestern Patagonia, Argentina. In this area, high-Andean vegetation occurs as islands on mountain tops above Nothofagus pumilio forests ? with the timberline at ca. 1700 m a.s.l. We recorded floristic, topographic and substrate data in 166 sites stratified according to longitude, altitude, slope and aspect. Vegetation data were classified with TWINSPAN and ordinated with Detrended Correspondence Analysis. The relationship between environmental and floristic variation was analysed using Canonical Correspondence Analysis. In order of importance, geographical longitude, altitude and aspect were the major determinants of vegetation variation, whereas substrate texture and slope appeared less important. The combination of these factors resulted in two main vegetation gradients. The first gradient is related to a moisture availability gradient, primarily determined by longitude and secondarily to variation in wind exposure (east vs. west aspect). The second vegetation gradient is related to variation in temperature, primarily determined by altitude, and secondarily by variation in insolation related to the contrast between north and south aspects. The four communities obtained with TWINSPAN are therefore associated with four characteristic habitat types: moist-cold, moist-warm, dry-cold and dry-warm. The community of warm and dry environments is the richest and has elements in common with dry steppe communities situated at lower elevations to the east, while the vegetation of the cold-moist habitat type has unique elements that are typical of the southern Andes. Although current climatic factors appear to be the major determinants of high-Andean vegetation gradients, historical events of Pleistocene times probably also affected the vegetation patterns we see today.     

A morphometric approach to the geographic variation of the terrestrial isopod species Armadillo tuberculatus (Isopoda: Oniscidea)

The terrestrial isopod species Armadillo tuberculatus Vogl, 1876 (Crustacea, Isopoda, Oniscidea) is a widely polymorphic species distributed in the south-central Aegean region (Greece) with a different morph on each island. Variation consists in coloration, size of cuticular tubercules, shape of telson and the shape of the male first pleopod exopodite (secondary sexual character of taxonomic importance). We studied the allometric growth of a cuticular tubercule in 17 populations (for both male and female individuals) and the shape variation of the first male pleopod exopodite in 10 populations using Elliptic Fourier Analysis, in order to test for patterns of intraspecific variation and possible relationships between morphs. In addition, Thin Plate Spline analysis was used for the calculation of the minimum bending energy between different exopodite shapes, which was then used for estimating the minimum spanning network (MSN) connecting them. The different allometric growth rates of the tubercule among island groups were significantly related to island latitude and climatic factors. On the other hand, the clustering of islands and the MSN based on male exopodite shape differences were not related to the palaeogeography of the Aegean region or to the present geographic distances of islands. These results are interpreted as evidence for non-adaptive radiation of the morphs.     

Chemical Composition and Antipathogenic Activity of Artemisia annua Essential Oil from Romania

The essential oil extracted by hydrodistillation from Romanian Artemisia annua aerial parts was characterized by GC/MS analysis, which allowed the identification of 94.64% of the total oil composition. The main components were camphor (17.74%), α‐pinene (9.66%), germacrene D (7.55%), 1,8‐cineole (7.24%), trans‐β‐caryophyllene (7.02%), and artemisia ketone (6.26%). The antimicrobial activity of this essential oil was evaluated by determining the following parameters: minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), minimal fungicidal concentration (MFC), and minimal biofilm eradication concentration (MBEC). Moreover, the soluble virulence factors were quantified with different biochemical substrates incorporated in the culture media. The reference and resistant, clinical strains proved to be susceptible to the A. annua oil, with MICs ranging from 0.51 to 16.33 mg/ml. The tested essential oil also showed good antibiofilm activity, inhibiting both the initial stage of the microbial cell adhesion to the inert substratum and the preformed mature biofilm. When used at subinhibitory concentrations, the essential oil proved to inhibit the phenotypic expression of five soluble virulence factors (hemolysins, gelatinase, DNase, lipases, and lecithinases). Briefly, the present results showed that the A. annua essential oil contained antimicrobial compounds with selective activity on Gram‐positive and Gram‐negative bacterial strains as well as on yeast strains and which also interfere with the expression of cell‐associated and soluble virulence factors.     

Wild Sicilian Rosemary: Phytochemical and Morphological Screening and Antioxidant Activity Evaluation of Extracts and Essential Oils

To identify the best biotypes, an extensive survey of Sicilian wild rosemary was carried out by collecting 57 samples from various sites, followed by taxonomic characterization from an agronomic perspective. All the biotypes collected were classified as Rosmarinus officinalis L. A cluster analysis based on the morphological characteristics of the plants allowed the division of the biotypes into seven main groups, although the characteristics examined were found to be highly similar and not area‐dependent. Moreover, all samples were analyzed for their phytochemical content, applying an extraction protocol to obtain the nonvolatile components and hydrodistillation to collect the essential oils for the volatile components. The extracts were characterized by LC‐UV‐DAD/ESI‐MS, and the essential oils by GC‐FID and GC/MS analyses. In the nonvolatile fractions, 18 components were identified, namely, 13 flavones, two organic acids, and three diterpenes. In the volatile fractions, a total of 82 components were found, with as predominant components α‐pinene and camphene among the monoterpene hydrocarbons and 1,8‐cineole, camphor, borneol, and verbenone among the oxygenated monoterpenes. Cluster analyses were carried out on both phytochemical profiles, allowing the separation of the rosemary samples into different chemical groups. Finally, the total phenol content and the antioxidant activity of the essential oils and extracts were determined with the Folin–Ciocalteu (FC) colorimetric assay, the UV radiation‐induced peroxidation in liposomal membranes (UV‐IP test), and the scavenging activity of the superoxide radical (O$\rm{{_{2}^{{^\cdot} -}}}$ ). The present study confirmed that the essential oils and organic extracts of the Sicilian rosemary samples analyzed showed a considerable antioxidant/free radical‐scavenging activity.     

基于SSR标记的越橘亲缘关系分析及品种鉴定

利用SSR标记对22个越橘栽培品种进行遗传差异及亲缘关系分析,并建立一套稳定的越橘品种鉴定体系,以期为越橘种质资源评价、鉴定、管理及越橘新品种培育奠定基础。本试验优化了一套越橘SSR-PCR反应体系,筛选出15个条带清晰、重复性好、多态性高的SSR标记,对22个越橘栽培品种进行亲缘关系分析,聚类结果与各品种的遗传背景以及表型呈现高度的一致性。从以上15个SSR标记中筛选出可用于越橘品种鉴定的SSR核心引物NA961和NA1040,核心引物组合能够完全区分22个越橘品种。用核心引物制作了参照分子量标记,构建了22个越橘品种的指纹图谱,建立了一套完整的越橘品种鉴定体系。实践验证SSR标记用于越橘品种鉴别的方法可行、结果可靠。     

Developments from analysis of variance through to generalized linear models and beyond

The collaborations between statisticians and biologists during the 100 years since AAB was founded have led to a very impressive list of statistical techniques, whose use now goes well beyond agriculture and biology. One example is the maximum likelihood methodology for probit analysis, arising from the collaboration between Sir Ronald Fisher and Chester Bliss. Others include analysis of variance, design of experiments, generalized linear models and the residual, or restricted, maximum likelihood (REML) algorithm for fitting unbalanced linear mixed models.