Mass spectrometry-based quantitative proteomic analysis of <Emphasis Type="Italic">Salmonella enterica</Emphasis> serovar Enteritidis protein expression upon exposure to hydrogen peroxide

Background  

Salmonella enterica, a common food-borne bacterial pathogen, is believed to change its protein expression profile in the presence of different environmental stress such as that caused by the exposure to hydrogen peroxide (H₂O₂), which can be generated by phagocytes during infection and represents an important antibacterial mechanism of host cells. Among Salmonella proteins, the effectors of Salmonella pathogenicity island 1 and 2 (SPI-1 and SPI-2) are of particular interest since they are expressed during host infection in vivo and are important for invasion of epithelial cells and for replication in organs during systemic infection, respectively. However, the expression profiles of these proteins upon exposure to H₂O₂ or to host cells in vivo during the established phase of systemic infection have not been extensively studied.     

Molecular genetic analysis of virus isolates from wild and cultivated plants demonstrates that East Africa is a hotspot for the evolution and diversification of Sweet potato feathery mottle virus

Sweet potato feathery mottle virus (SPFMV, genus Potyvirus) is globally the most common pathogen of cultivated sweet potatoes (Ipomoea batatas; Convolvulaceae). Although more than 150 SPFMV isolates have been sequence‐characterized from cultivated sweet potatos across the world, little is known about SPFMV isolates from wild hosts and the evolutionary forces shaping SPFMV population structures. In this study, 46 SPFMV isolates from 14 wild species of genera Ipomoea, Hewittia and Lepistemon (barcoded for the matK gene in this study) and 13 isolates from cultivated sweet potatoes were partially sequenced. Wild plants were infected with the EA, C or O strain, or co‐infected with the EA and C strains of SPFMV. In East Africa, SPFMV populations in wild species and sweet potato were genetically undifferentiated, suggesting inter‐host transmission of SPFMV. Globally, spatial diversification of the 178 isolates analysed was observed, strain EA being largely geographically restricted to East Africa. Recombination was frequently detected in the 6K2‐VPg‐NIaPro region of the EA strain, demonstrating a recombination ‘hotspot’. Recombination between strains EA and C was rare, despite their frequent co‐infections in wild plants, suggesting purifying selection against strain EA/C recombinants. Positive selection was predicted on 17 amino acids distributed over the entire coat protein in the globally distributed strain C, as compared to only four amino acids in the coat protein N‐terminus of the EA strain. This selection implies a more recent introduction of the C strain and a higher adaptation of the EA strain to the local ecosystem. Thus, East Africa appears as a hotspot for evolution and diversification of SPFMV.     

Sesquiterpene lactones from the aerial parts of Anthemis arvensis L.

Two known sesquiterpene lactones, antheindurolides A and B, together with five new related lactones with the same unusual skeleton were isolated from the aerial parts of Anthemis arvensis growing in Serbia. The originally proposed structure of antheindurolide B was revised. This (antheindurolide) type of lactones, detected so far only in the genus Anthemis (Anthemis indurata, Anthemis pseudocotula and Anthemis cotula) could be of chemotaxonomic significance.     

K+ channel KV3.1 associates with OSP/claudin-11 and regulates oligodendrocyte development

K⁺ channels are differentially expressed throughout oligodendrocyte (Olg) development. K_V1 family voltage-sensitive K⁺ channels have been implicated in proliferation and migration of Olg progenitor cell (OPC) stage, and inward rectifier K+ channels (K_IR)4.1 are required for OPC differentiation to myelin-forming Olg. In this report we have identified a Shaw family K⁺ channel, K_V3.1, that is involved in proliferation and migration of OPC and axon myelination. Application of anti-K_V3.1 antibody or knockout of Kv3.1 gene decreased the sustained K⁺ current component of OPC by 50% and 75%, respectively. In functional assays block of K_V3.1-specific currents or knockout of Kv3.1 gene inhibited proliferation and migration of OPC. Adult Kv3.1 gene-knockout mice had decreased diameter of axons and decreased thickness of myelin in optic nerves compared with age-matched wild-type littermates. Additionally, K_V3.1 was identified as an associated protein of Olg-specific protein (OSP)/claudin-11 via yeast two-hybrid analysis, which was confirmed by coimmunoprecipitation and coimmunohistochemistry. In summary, the K_V3.1 K⁺ current accounts for a significant component of the total K⁺ current in cells of the Olg lineage and, in association with OSP/claudin-11, plays a significant role in OPC proliferation and migration and myelination of axons. membrane potential; tight junction; myelin; progenitor cell     

Angucyclines Sch 47554 and Sch 47555 from Streptomyces sp. SCC-2136: cloning, sequencing, and characterization

The entire gene cluster involved in the biosynthesis of angucyclines Sch 47554 and Sch 47555 was cloned, sequenced, and characterized. Analysis of the nucleotide sequence of genomic DNA spanning 77.5-kb revealed a total of 55 open reading frames, and the deduced products exhibited strong sequence similarities to type II polyketide synthases, deoxysugar biosynthetic enzymes, and a variety of accessory enzymes. The involvement of this gene cluster in the pathway of Sch 47554 and Sch 47555 was confirmed by genetic inactivation of the aromatase, including a portion of the ketoreductase, which was disrupted by inserting the thiostrepton gene.     

Examination of halogen substituent effects on HIV-1 integrase inhibitors derived from 2,3-dihydro-6,7-dihydroxy-1H-isoindol-1-ones and 4,5-dihydroxy-1H-isoindole-1,3(2H)-diones

Using 2,3-dihydro-6,7-dihydroxy-1H-isoindol-1-one and 4,5-dihydroxy-1H-isoindole-1,3(2H)-dione based HIV-1 integrase inhibitors as display platforms, we undertook a thorough examination of the effects of modifying the halogen substituents on a key benzyl ring that is hypothesized to bind in a hydrophobic pocket of the integrase·DNA complex. Data from this study suggest that in general dihalo-substituted analogues have higher potency than monohalo-substituted compounds, but that further addition of halogens is not beneficial.     

Rapid and Effective Method of RNA Isolation from Green Microalga <Emphasis Type="Italic">Ankistrodesmus convolutus</Emphasis>

The rapid and effective method for the isolation of RNA from green microalga Ankistrodesmus convolutus based on homogenization in a simple CTAB buffer and selective precipitation of RNA with lithium chloride is developed. This procedure avoids the use of toxic chaotropic agents and phenol while high concentration of dithiothreitol is used to inhibit RNase activity and prevent oxidative cross-linking of nucleic acids by phenolics. The extraction procedure was able to produce high quality and intact RNA from A. convolutus. The yield of total RNA was 0.69–0.73 mg/g of fresh weight, with A₂₆₀/A₂₈₀ ratio of 1.79–1.86. The obtained RNA was of sufficient quality and suitable for downstream application such as RT-PCR and cDNA library construction. The procedure may also have wider applicability for total RNA isolation from other green microalgae species.     

Manglietia sapaensis N. H. Xia & Q. N. Vu sp. nov. (Magnoliaceae) from Vietnam

A new species of the family Magnoliaceae, Manglietia sapaensis N. H. Xia & Q. N. Vu from Lao Cai Province, northern Vietnam, is described and illustrated. The well marked species appears to be most closely related to M. garrettii Craib, but differs in being a smaller tree, with shorter petioles not pulvinate at base, leaf‐lamina oblong to oblong‐elliptic, white flowers, and pubescent gynoecium.