Somatic antigens of pseudomonads: structure of the O-specific polysaccharide of Pseudomonas fluorescens IMV 2366 (biovar C)

The O-specific polysaccharide of P. fluorescens IMV 2366 was studied by sugar and methylation analyses along with 1H and 13C NMR spectroscopy, including 2D gsCOSY, TOCSY, gsNOESY, H-detected 1H,(13)C gsHSQC, HMQC-TOCSY, and gsHMBC experiments. The polysaccharide contains L-rhamnose, 2-acetamido-2,6-dideoxy-D-galactose (D-FucNAc) and 3-acylamido-3,6-dideoxy-D-glucose (D-Qui3NAcyl, where Acyl is 3-hydroxy-2,3-dimethyl-5-oxoprolyl). The structure 1 of the polysaccharide was found to be similar to the structure 2 of a 6-deoxy-L-talose (L-6dTal)-containing O-specific polysaccharide of a non-classified P. fluorescens strain, 361, studied earlier [Khomenko, V. A.; Naberezhnykh, G. A.; Isakov, V. V.; Solov'eva, T. F.; Ovodov, Y. S.; Knirel, Y. A.; Vinogradov, E. V. Bioorg. Khim. 1986, 12, 1641-1648; Naberezhnykh, G. A.; Khomenko, V. A.; Isakov, V. V., El'kin, Y. N.; Solov'eva, T. F.; Ovodov, Y. S. Bioorg. Khim. 1987, 13, 1428-1429]. --> 2)-beta-D-Quip3NAcyl-(1 --> 3)-alpha-L-Rhap-(1 --> 3)-alpha-D-FucpNAc-(1 --> 1. --> 4)-beta-D-Quip3NAcyl-(1 --> 3)-alpha-L-6dTalp4Ac-(1 --> 3)-alpha-D-FucpNAc-(1 -->2.     

SNAP-23 functions in docking/fusion of granules at low Ca2+

Ca(2+)-triggered exocytosis of secretory granules mediates the release of hormones from endocrine cells and neurons. The plasma membrane protein synaptosome-associated protein of 25 kDa (SNAP-25) is thought to be a key component of the membrane fusion apparatus that mediates exocytosis in neurons. Recently, homologues of SNAP-25 have been identified, including SNAP-23, which is expressed in many tissues, albeit at different levels. At present, little is known concerning functional differences among members of this family of proteins. Using an in vitro assay, we show here that SNAP-25 and SNAP-23 mediate the docking of secretory granules with the plasma membrane at high (1 microM) and low (100 nM) Ca(2+) levels, respectively, by interacting with different members of the synaptotagmin family. In intact endocrine cells, expression of exogenous SNAP-23 leads to high levels of hormone secretion under basal conditions. Thus, the relative expression levels of SNAP-25 and SNAP-23 might control the mode (regulated vs. basal) of granule release by forming docking complexes at different Ca(2+) thresholds.     

Plant performance in stressful environments: interpreting new and established knowledge of the roles of arbuscular mycorrhizas

Arbuscular mycorrhizal (AM) symbioses are formed by approximately 80% of vascular plant species in all major terrestrial biomes. In consequence an understanding of their functions is critical in any study of sustainable agricultural or natural ecosystems. Here we discuss the implications of recent results and ideas on AM symbioses that are likely to be of particular significance for plants dealing with abiotic stresses such as nutrient deficiency and especially water stress. In order to ensure balanced coverage, we also include brief consideration of the ways in which AM fungi may influence soil structure, carbon deposition in soil and interactions with the soil microbial and animal populations, as well as plant-plant competition. These interlinked outcomes of AM symbioses go well beyond effects in increasing nutrient uptake that are commonly discussed and all require to be taken into consideration in future work designed to understand the complex and multifaceted responses of plants to abiotic and biotic stresses in agricultural and natural environments.     

Immunochemical Characterization of the Capsular Polysaccharide of Azospirillum irakense KBC1

The repeating unit structure of Azospirillum irakense KBC1 capsular polysaccharide (CPS) was established and was found to be identical to that of the O polysaccharide of A. irakense KBC1 lipopolysaccharide (LPS). The antigenic heterogeneity of the LPS and the CPS was shown to be related to differences in the macromolecular organization of these glycopolymers. After an immune response activation, R-form CPS molecules were found to be predominant.     

Evidence for Shared Cognitive Processing of Pitch in Music and Language

Language and music epitomize the complex representational and computational capacities of the human mind. Strikingly similar in their structural and expressive features, a longstanding question is whether the perceptual and cognitive mechanisms underlying these abilities are shared or distinct – either from each other or from other mental processes. One prominent feature shared between language and music is signal encoding using pitch, conveying pragmatics and semantics in language and melody in music. We investigated how pitch processing is shared between language and music by measuring consistency in individual differences in pitch perception across language, music, and three control conditions intended to assess basic sensory and domain-general cognitive processes. Individuals’ pitch perception abilities in language and music were most strongly related, even after accounting for performance in all control conditions. These results provide behavioral evidence, based on patterns of individual differences, that is consistent with the hypothesis that cognitive mechanisms for pitch processing may be shared between language and music.     

The role of the permanent soil seed bank in early stages of a post-agricultural succession in the Inland Pampa,Argentina

We studied the soil seed bank composition in four old fields of different ages, after abandonment from agriculture. Complete seed bank composition was assessed by direct seed separation from soil samples and identification to species. Most species found in the seed bank were not important in the present seral communities. Seed of the species that dominated the early succession were generally not found. Additionally, there were very few propagules rather than on the germination of in situ propagules. We suggest that pampean grasses evolved under that the course of post-agricultural succession will depend strongly on the pattern of arrival of exogenous propagules rather than the germination of in situ propagules. We suggest that pampean grasses evolved under disturbances of low intensity and/or a disturbance regime dominated by small gaps, in which open areas could be rapidly colonized from the edges and/or by remnant vegetative propagules. The changes produced by the introduction of agriculture triggered the invasion by exotic species adapted to the new disturbance regime.     

Immunization with Pre-Erythrocytic Antigen CelTOS from Plasmodium falciparum Elicits Cross-Species Protection against Heterologous Challenge with Plasmodium berghei

Background

The Plasmodium protein Cell-traversal protein for ookinetes and sporozoites (CelTOS) plays an important role in cell traversal of host cells in both, mosquito and vertebrates, and is required for successful malaria infections. CelTOS is highly conserved among the Plasmodium species, suggesting an important functional role across all species. Therefore, targeting the immune response to this highly conserved protein and thus potentially interfering with its biological function may result in protection against infection even by heterologous species of Plasmodium.

Methodology/Principal Findings

To test this hypothesis, we developed a recombinant codon-harmonized P. falciparum CelTOS protein that can be produced to high yields in the E. coli expression system. Inbred Balb/c and outbred CD-1 mice were immunized with various doses of the recombinant protein adjuvanted with Montanide ISA 720 and characterized using in vitro and in vivo analyses.

Conclusions/Significance

Immunization with PfCelTOS resulted in potent humoral and cellular immune responses and most importantly induced sterile protection against a heterologous challenge with P. berghei sporozoites in a proportion of both inbred and outbred mice. The biological activity of CelTOS-specific antibodies against the malaria parasite is likely linked to the impairment of sporozoite motility and hepatocyte infectivity. The results underscore the potential of this antigen as a pre-erythrocytic vaccine candidate and demonstrate for the first time a malaria vaccine that is cross-protective between species.     

Structure of the O-polysaccharide of the lipopolysaccharide of Pragia fontium 97U116

The O-polysaccharide of Pragia fontium 97U116 was obtained by mild acid degradation of the lipopolysaccharide and studied by sugar analysis along with 1D and 2D ¹H and ¹³C NMR spectroscopy. The following structure of the pentasaccharide-repeating unit was established: →2)-α-d-Galf-(1→3)-α-l-Rhap2Ac^I-(1→4)-α-d-GlcpNAc^I-(1→2)-α-l-Rhap^II-(1→3)-β-d-GlcpNAc^II-(1→     

Antioxidant effects of the VO(IV) hesperidin complex and its role in cancer chemoprevention

Vanadium compounds are known for a variety of pharmacological properties. Many of them display antitumoral and osteogenic effects in several cell lines. Free radicals induce the development of tumoral processes. Natural polyphenols such as flavonoids have antioxidant properties since they scavenge different free radicals. For these reasons it is interesting to investigate the effects of a new complex generated between the vanadyl(IV) cation and the flavonoid hesperidin. The complex has been synthesized and characterized by physicochemical methods. Spectroscopic analysis revealed a 1:1 stoichiometry of ligand:VO and coordination by deprotonated cis-hydroxyl groups to the disaccharide moiety of the ligand. The complex improves the superoxide dismutase (SOD)-like activity of the ligand, but the scavenging of other radicals tested does not change upon complexation. When tested on two tumoral cell lines in culture (one of them derived from a rat osteosarcoma UMR106 and the other from human colon adenocarcinoma Caco-2), the complex enhanced the antiproliferative effects of the free ligand, and this effect correlated with the morphological alterations toward apoptosis. Also, on the osteoblastic cell line the complex stimulated cell proliferation and collagen type I production at low concentrations. At higher doses the complex behaved as a cytotoxic compound for the osteoblasts.