Relationship between Tobacco,cagA and vacA i1 Virulence Factors and Bacterial Load in Patients Infected by Helicobacter pylori

MethodsBiopsies of the gastric corpus and antrum from 155 consecutive patients in whom there was clinical suspicion of infection by H. pylori were processed. In 106 patients H. pylori infection was detected. Molecular methods were used to quantify the number of microorganisms and presence of cagA and vacA i1 genes. A standardized questionnaire was used to obtain patients’ clinical data and lifestyle variables, including tobacco and alcohol consumption. Adjusted Odds Ratios (OR_adjusted) were estimated by unconditional logistic regression.ResultscagA was significantly associated with active-smoking at endoscope: OR_adjusted 4.52. Evidence of association was found for vacA i1 (OR_adjusted 3.15). Bacterial load was higher in active-smokers, although these differences did not yield statistical significance (median of 262.2 versus 79.4 copies of H. pylori per cell).ConclusionsThe association between smoking and a higher risk of being infected by a virulent bacterial population and with higher bacterial load, support a complex interaction between H. pylori infection and environmental factors.     

Biogeography of sponge chemical ecology: comparisons of tropical and temperate defenses

Examples from both marine and terrestrial systems have supported the hypothesis that predation is higher in tropical than in temperate habitats and that, as a consequence, tropical species have evolved more effective defenses to deter predators. Although this hypothesis was first proposed for marine sponges over 25 years ago, our study provides the first experimental test of latitudinal differences in the effectiveness of sponge chemical defenses. We collected 20 common sponge species belonging to 14 genera from tropical Guam and temperate Northeast Spanish coasts (Indo-Pacific and Mediterranean biogeographic areas) and conducted field-based feeding experiments with large and small fish predators in both geographic areas. We use the term global deterrence to describe the deterrent activity of a sponge extract against all of the predators used in our experiments and to test the hypothesis that sponges from Guam are chemically better defended than their Mediterranean counterparts. Sympatric and allopatric deterrence refer to the average deterrent activity of a sponge against sympatric or allopatric predators. All of the sponges investigated in this study showed deterrent properties against some predators. However, 35% of the sponge species were deterrent in at least one but not in all the experiments, supporting the idea that predators can respond to chemical defenses in a species-specific manner. Tropical and temperate sponges have comparable global, sympatric, and allopatric deterrence, suggesting not only that chemical defenses from tropical and temperate sponges are equally strong but also that they are equally effective against sympatric and allopatric predators. Rather than supporting geographic trends in the production of chemical defenses, our data suggest a recurrent selection for chemical defenses in sponges as a general life-history strategy.     

Morphological characterization of extrafloral nectaries and associated ants in tropical vegetation of Los Tuxtlas,Mexico

Extrafloral nectaries (EFNs) are glands that produce sugary exudates and can be located in any vegetative or reproductive structure of the plant. The EFNs occur in different locations on the leaves, stems, inflorescences and flowers (but are not directly involved with pollination). Occurrence of EFNs on plants of coastal vegetation, tropical rain forest and cloud forest in southern Mexico was studied within Los Tuxtlas Biosphere Reserve, Veracruz. We focused on determining the identity and species richness of plants with EFNs, and describing EFNs morphologies. We found 50 species of plants with EFNs (16 families, 31 genera), which corresponds to approximately 5% of the flora reported for the field site (943 species). Trees were the life form with the greatest representation of EFNs while shrubs and epiphytes had the least representation. EFN-bearing plants were particularly well represented in the families Fabaceae, Euphorbiaceae, Convolvulaceae, Bignoniaceae, Malpighiaceae, Passifloraceae, Costaceae, Tiliaceae, while eight other families had only one species. We found six different types of EFNs according to their morphological structure. Dissimilarity analyses between plants and ant species showed that the forest in the Los Tuxtlas region has a rich array of ant species associated with EFNs, with a low niche overlap of ant species. This diversification in ant use of EFNs is of particular interest from an ecological and evolutionary perspective (potential mutualisms with adaptative value), but this deserves still further studies in detail. The present study shall provide basic information for future research in these fields of plant–animal interactions in neotropical vegetation.     

Dynamics of EF-G interaction with the ribosome explored by classification of a heterogeneous cryo-EM dataset

A method of supervised classification using two available structure templates was applied to investigate the possible heterogeneity existing in a large cryo-EM dataset of an Escherichia coli 70S ribosome-EF-G complex. Two subpopulations showing the ribosome in distinct conformational states, related by a ratchet-like rotation of the 30S subunit with respect to the 50S subunit, were extracted from the original dataset. The possible presence of additional intermediate states is discussed.     

Latitudinal and altitudinal patterns of plant community diversity on mountain summits across the tropical Andes

The high tropical Andes host one of the richest alpine floras of the world, with exceptionally high levels of endemism and turnover rates. Yet, little is known about the patterns and processes that structure altitudinal and latitudinal variation in plant community diversity. Herein we present the first continental‐scale comparative study of plant community diversity on summits of the tropical Andes. Data were obtained from 792 permanent vegetation plots (1 m²) within 50 summits, distributed along a 4200 km transect; summit elevations ranged between 3220 and 5498 m a.s.l. We analyzed the plant community data to assess: 1) differences in species abundance patterns in summits across the region, 2) the role of geographic distance in explaining floristic similarity and 3) the importance of altitudinal and latitudinal environmental gradients in explaining plant community composition and richness. On the basis of species abundance patterns, our summit communities were separated into two major groups: Puna and Páramo. Floristic similarity declined with increasing geographic distance between study‐sites, the correlation being stronger in the more insular Páramo than in the Puna (corresponding to higher species turnover rates within the Páramo). Ordination analysis (CCA) showed that precipitation, maximum temperature and rock cover were the strongest predictors of community similarity across all summits. Generalized linear model (GLM) quasi‐Poisson regression indicated that across all summits species richness increased with maximum air temperature and above‐ground necromass and decreased on summits where scree was the dominant substrate. Our results point to different environmental variables as key factors for explaining vertical and latitudinal species turnover and species richness patterns on high Andean summits, offering a powerful tool to detect contrasting latitudinal and altitudinal effects of climate change across the tropical Andes.     

A synthetic peptide homologous to functional domain of human IL-10 down-regulates expression of MHC class I and Transporter associated with Antigen Processing 1/2 in human melanoma cells

Tumor cells treated with IL-10 were shown to have decreased, but peptide-inducible expression of MHC class I, decreased sensitivity to MHC class I-restricted CTL, and increased NK sensitivity. These findings could be explained, at least partially, by a down-regulation of TAP1/TAP2 expression. In this study, IT9302, a nanomeric peptide (AYMTMKIRN), homologous to the C-terminal of the human IL-10 sequence, was demonstrated to mimic these previously described IL-10 effects on MHC class I-related molecules and functions. We observed a dose-dependent down-regulation of MHC class I at the cell surface of melanoma cells after 24-h treatment with IT9302. The IL-10 homologue peptide also caused a dose-dependent inhibition of the IFN-gamma-mediated surface induction of MHC class I in a melanoma cell line. We demonstrated, using Western blot and flow cytometry, that IT9302 inhibits the expression of TAP1 and TAP2 proteins, but not MHC class I H chain or low molecular protein molecules. Finally, peptide-treated melanoma cells were shown to be more sensitive to lysis by NK cells in a dose-dependent way. Taken together, these results demonstrate that a small synthetic peptide derived from IL-10 can mimic the Ag presentation-related effects mediated by this cytokine in human melanomas and increase tumor sensitivity to NK cells, which can be relevant in the designing of future strategies for cancer immune therapy.     

Isolation and characterization of microsatellite loci from the endangered Mediterranean sponge Spongia agaricina (Demospongiae: Dictyoceratida)

The abundance of the bath sponge Spongia agaricina has decreased drastically in recent years and it is now considered an endangered species under Annex 3 of Bern and Barcelona conventions. We describe eight microsatellite markers and present data on their allelic variation and utility as high resolution genetic markers. We analyzed 36 individuals from two populations and found that the number of alleles per locus ranged between 1 and 7. Observed heterozygosity ranged from 0 to 0.72. We found deviations from Hardy–Weinberg expectations for some loci. We exclusively detected null alleles for those loci that deviated from Hardy–Weinberg expectations. Also, distributions of allele frequencies differed significantly between the two populations, making them suitable for population genetic analyses.     

Coralline algae indicate Pleistocene evolution from deep,open platform to outer barrier reef environments in the northern Great Barrier Reef margin

Coralline algae from a drill core in Ribbon Reef 5 have been used to interpret changes in the depositional palaeoenvironments in the northern Australian Great Barrier Reef over the last 790 ka. Three main coralline algal assemblages, each dominated by members of a particular subfamily, have been distinguished by quantitative analysis: (1) mastophoroid assemblages, usually occurring as crusts on corals, are typical of the shallowest reef settings; (2) lithophylloid assemblages within algal nodules may represent shallow-water, cooler environments or deeper reef subenvironments; and (3) melobesioid assemblages are characteristic of deeper-water platform areas. The algal assemblages between 96 and 210 m b.s.f. (metre below sea floor) record a fluctuating but progressive shallowing-upwards from deep, outer-platform to shallower, non-reefal depositional environments. Two intervening episodes dominated by mastophoroids represent two phases of reef growth. The section above 96 m b.s.f. comprises several stacked reefs in which mastophoroid crusts similar to the present-day shallow-water assemblages predominate.Electronic Supplementary Material Supplementary material is available for this article at .Communicated by: Geological Editor P.K. Swart