Biophysical characterization and vector-specific antagonist activity of domain III of the tick-borne flavivirus envelope protein

The molecular determinants responsible for flavivirus host cell binding and tissue tropism are largely unknown, although domain III of the envelope protein has been implicated in these functions. We examined the solution properties and antagonist activity of Langat virus domain III. Our results suggest that domain III adopts a stably folded structure that can mediate binding of tick-borne flaviviruses but not mosquito-borne flaviviruses to their target cells. Three clusters of phylogenetically conserved residues are identified that may be responsible for the vector-specific antagonist activity of domain III.     

Sixty simple sequence repeat markers for use in the Festuca–Lolium complex of grasses

So far only very few simple sequence repeat (SSR) markers developed from grass species have had their primer sequences published. To make more markers available to the scientific community, we isolated and sequenced 256 microsatellite‐containing clones from four genome libraries of a Lolium multiflorum×Festuca glaucescens F₁ hybrid following enrichment in (TC)_n, (TG)_n, or both repeats. In this work, we report the primer sequences of 60 SSRs including preliminary results of polymorphism for mapping.     

悬钩子属植物化学成分及药理活性研究进展

本文对近10年来悬钩子属植物的化学成分和药理活性研究进行了综述,为该属植物的进一步开发利用提供参考。悬钩子属植物的化学成分主要包括黄酮、萜、鞣质、甾等。药理活性主要包括抗菌、抗炎、抗肿瘤、抗氧化、抗过敏、保肝、镇痛等。     

Microbial Community Structure and Metabolic Potential of the Hyporheic Zone of a Large Mid-Stream Channel Bar

Abstract

To develop a greater understanding of hyporheic zone microbial biogeochemistry, we sampled pore fluids from a piezometer array associated with the McCarran Ranch channel bar (MRCB); a partially submerged cobble island in the Truckee River, NV, USA. Flowing surface water and pumped pore fluids were characterized by prokaryotic community structure, metabolic potential, and aqueous physicochemistry. Concentrations of potential respiratory electron acceptors were highest in surface water and riverbed porewater and sequentially depleted in porewaters along the inferred flowpath (O₂, then NO₃^?, then SO₄^2?). Correspondingly, cultivable nitrate reducers/denitrifiers were most abundant in surface water and riverbed porewater, despite oxic conditions. Cultivable sulfate reducers were overall most abundant in surface water. Prokaryotic community reconstruction from 16S rRNA gene sequences indicates that the surface water community was less diverse than that of porewater and supports a shift in metabolic strategy, from aerobic heterotrophy in surface water (e.g., Comamonadaceae and Sporichthyaceae) to chemolithotrophy and anaerobic metabolisms (e.g., Hydrogenophaga spp., Ferribacterium spp., Methanobacterium spp.) along the hyporheic flow path. These data indicate that prokaryotic communities within the MRCB are phylogenetically and metabolically diverse and contribute to biogeochemical cycling in this common yet relatively understudied habitat.     

Survival and Body Condition of Raccoons at the Edge of the Range

ABSTRACT We investigated the influence of intrinsic and extrinsic variables on overwinter survival of raccoons (Procyon lotor; n = 114) at the northern edge of their distribution. A Cox proportional hazard model identified winter severity as the variable with the greatest influence on raccoon survival (β = 1.08). Autumn body condition estimates (20.5 ± 0.46% total body fat) were relatively stable across years even though we observed large differences in autumn food indices. Variations in autumn body condition did not explain heterogeneity observed in overwinter survival nor the spring condition in which raccoons emerged. Relatively constant autumn body condition suggests reliable availability of anthropogenic food resources may negate variations observed in natural food items on which raccoons rely during hyperphagia. Conversely, spring body condition did vary among years and was highly correlated with winter severity. Accordingly, we also observed a strong inverse relationship with overwinter survival and winter severity. Our findings indicate winter climatic constraints are important factors governing the northern limit of raccoon distribution and changes in winter severity could have important implications in further range expansion of this species.     

A monoclonal antibody to visualize PtdIns(3,4,5)P(3) in cells.

Phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P(3)] is a second messenger produced in response to agonist stimulation. Traditionally, visualization of phosphoinositide polyphosphates (PtdInsP(n)) in living cells is accomplished using chimeric green fluorescent protein (GFP)-pleckstrin homology (PH) domain proteins, while PtdInsP(n) quantitation is accomplished by extraction and separation of radiolabeled cellular PtdInsP(n)s. Here we describe preparation of a covalent protein-PtdIns(3,4,5)P(3) immunogen, characterization of binding selectivity of an anti-PtdIns(3,4,5)P(3) IgM, and immunodetection of PtdIns(3,4,5)P(3) in stimulated mammalian cells. This antibody has greater than three orders of magnitude selectivity for binding PtdIns(3,4,5)P(3) relative to its precursor, phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)), and is therefore optimal for studies of cell function. The immunodetection in platelet-derived growth factor (PDGF)-stimulated NIH 3T3 cells was benchmarked against HPLC analysis of [3H]-myo-inositol-labeled cellular PtdInsP(n)s. In addition, the changes in subcellular amounts and localizations of both PtdIns(3,4,5)P(3) and PtdIns(4,5)P(2) in stimulated NIH 3T3 fibroblasts and human neutrophils were observed by immunofluorescence. In insulin- or PDGF-stimulated fibroblasts, PtdIns(3,4,5)P(3) levels increased in the cytoplasm, peaking at 10 min. In contrast, increases in the PtdIns(4,5)P(2) levels were detected in nuclei, corresponding to the production of new substrate following depletion by phosphoinositide (PI) 3-kinase.     

INSULIN PRODUCES A BIPHASIC RESPONSE INTETRAHYMENA THERMOPHILABY STIMULATING CELL SURVIVAL AND ACTIVATING PROLIFERATION IN TWO SEPARATE CONCENTRATION INTERVALS

Cells ofTetrahymenamay produce autocrine signal molecules with effects on survival and proliferation. Here we have tested the effects of human recombinant and bovine insulin, and the B22–B30 fragment of bovine insulin over a wide range of concentrations (10^?5–10^?18m ) on cell survival and proliferation in a synthetic nutrient medium. The cells were grown in conical flasks at low initial cell densities (40 and 400cells/ml). Insulin prevented rapid cell death and/or promoted cell proliferation over two separate concentration ranges: down to nanomolar levels and again in the low pico- and femtomolar range. At an initial population density of 400cells/ml the cells multiplied at both concentration intervals. At 40 or fewer organisms/ml the cells multiplied in the high concentration interval, whereas in the low interval they survived for about four times longer than those in the control cultures. B22–B30 added to cultures of 40 initial cells/ml produced a stimulation of cell survival in the low pico- and high femtomolar range. In the presence of hemin (50nm ) cells at 400 initial organisms/ml multiplied at insulin concentrations down to about 3nm and again from 300am to 10pm . In some cases, hemin plus insulin activated cell proliferation between the two concentration intervals as well. At 40cells/ml the cells not only survived but proliferated in the femtomolar range. Cells in cultures supplemented with both hemin and B22–B30 multiplied at the low concentration interval (from about 100fm to 10pm ).     

Specific localization of scallop gill epithelial calmodulin in cilia

Calmodulin has been isolated and characterized from the gill of the bay scallop aequipecten irradians. Quantitative electrophoretic analysis of epithelial cell fractions show most of the calmodulin to be localized in the cilia, specifically in the detergent- solubilized membrane-matrix fraction. Calmodulin represents 2.2 +/- 0.3 percent of the membrane-matrix protein or 0.41 +/- 0.5 percent of the total ciliary protein. Its concentration is at least 10(-4) M if distributed uniformly within the matrix. Extraction in the presence of calcium suggests that the calmodulin is not bound to the axoneme proper. The ciliary protein is identified as a calmodulin on the basis of its calcium- dependent binding to a fluphenazine-sepharose affinity column and its comigration with bovine brain calmodulin on alkaline-urea and SDS polyacrylamide gels in both the presence and absence of calcium. Scallop ciliary calmodulin activates bovine brain phosphodiesterase to the same extent as bovine brain and chicken gizzard calmodulins. Containing trimethyllysine and lacking cysteine and tryptophan, the amino acid composition of gill calmodulin is typical of known calmodulins, except that it is relatively high in serine and low in methionine. Its composition is less acidic than other calmodulins, in agreement with an observed isoelectric point approximately 0.2 units higher than that of bovine brain. Comparative tryptic peptide mapping of scallop gill ciliary and bovine brain calmodulins indicates coincidence of over 75 percent of the major peptides, but at least two major peptides in each show no near-equivalency. Preliminary results using ATP-reactivated gill cell models show no effect of calcium at micromolar levels on ciliary beat or directionality of the lateral cilia, the cilia which constitute the vast majority of those isolated. However, ciliary arrest will occur at calcium levels more than 150 muM. Because calmodulin usually functions in the micromolar range, its role in this system is unclear. Scallop gill ciliary calmodulin may be involved in the direct regulation of dyneintubule sliding, or it may serve some coupled calcium transport function. At the concentration in which it is found, it must also at least act as a calcium buffer.     

Relation entre réaction géotropique et évolution du statenchyme dans la racine d'Asperge

Relationship between the Geotropic Response and the Evolution of the Statenchyma in Roots of Asparagus officinalis. The evolution of the statenchyma in roots of Asparagus of ficinalis seedlings, grown in obscurity, was followed during the first 17 days. After 7 days of etiolation, a decrease of both the average diameter of the amyloplasts and the average number of these organelles was observed in the central root cap cells. If the seedlings were illuminated (with white light) from the 7th day, the average number of statoliths increased rapidly in the statocytes. The volume of these organelles undergoes the same variation in etiolated and in illuminated plants. The initial rate of curvature (V_i) of the roots (stimulated in a horizontal position) and the volume of amyloplasts (V_ac) in their caps were analysed as a function of the time of germination in obscurity (from the 8th to the 17th day). It was found that V_i increased as a linear function of the logarithm of V_ac, which confirms that the weight of the amyloplasts of the statocytes may play a role in the geotropic stimulation of the roots.