Comparative Composition, Diversity and Trophic Ecology of Sediment Macrofauna at Vents, Seeps and Organic Falls

Sediments associated with hydrothermal venting, methane seepage and large organic falls such as whale, wood and plant detritus create deep-sea networks of soft-sediment habitats fueled, at least in part, by the oxidation of reduced chemicals. Biological studies at deep-sea vents, seeps and organic falls have looked at macrofaunal taxa, but there has yet to be a systematic comparison of the community-level attributes of sediment macrobenthos in various reducing ecosystems. Here we review key similarities and differences in the sediment-dwelling assemblages of each system with the goals of (1) generating a predictive framework for the exploration and study of newly identified reducing habitats, and (2) identifying taxa and communities that overlap across ecosystems. We show that deep-sea seep, vent and organic-fall sediments are highly heterogeneous. They sustain different geochemical and microbial processes that are reflected in a complex mosaic of habitats inhabited by a mixture of specialist (heterotrophic and symbiont-associated) and background fauna. Community-level comparisons reveal that vent, seep and organic-fall macrofauna are very distinct in terms of composition at the family level, although they share many dominant taxa among these highly sulphidic habitats. Stress gradients are good predictors of macrofaunal diversity at some sites, but habitat heterogeneity and facilitation often modify community structure. The biogeochemical differences across ecosystems and within habitats result in wide differences in organic utilization (i.e., food sources) and in the prevalence of chemosynthesis-derived nutrition. In the Pacific, vents, seeps and organic-falls exhibit distinct macrofaunal assemblages at broad-scales contributing to ß diversity. This has important implications for the conservation of reducing ecosystems, which face growing threats from human activities

Prevention of methamphetamine-induced microglial cell death by TNF-α and IL-6 through activation of the JAK-STAT pathway

<p><b>Abstract</b></p> <p><b>Background</b></p> <p>It is well known that methamphetamine (METH) is neurotoxic and recent studies have suggested the involvement of neuroinflammatory processes in brain dysfunction induced by misuse of this drug. Indeed, glial cells seem to be activated in response to METH, but its effects on microglial cells are not fully understood. Moreover, it has been shown that cytokines, which are normally released by activated microglia, may have a dual role in response to brain injury. This led us to study the toxic effect of METH on microglial cells by looking to cell death and alterations of tumor necrosis factor-alpha (TNF-α) and interleukine-6 (IL-6) systems, as well as the role played by these cytokines.</p> <p><b>Methods</b></p> <p>We used the N9 microglial cell line, and cell death and proliferation were evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling assay and incorporation of bromodeoxyuridine, respectively. The TNF-α and IL-6 content was quantified by enzyme-linked immunosorbent assay, and changes in TNF receptor 1, IL-6 receptor-alpha, Bax and Bcl-2 protein levels by western blotting. Immunocytochemistry analysis was also performed to evaluate alterations in microglial morphology and in the protein expression of phospho-signal transducer and activator of transcription 3 (pSTAT3).</p> <p><b>Results</b></p> <p>METH induced microglial cell death in a concentration-dependent manner (EC₅₀ = 1 mM), and also led to significant morphological changes and decreased cell proliferation. Additionally, this drug increased TNF-α extracellular and intracellular levels, as well as its receptor protein levels at 1 h, whereas IL-6 and its receptor levels were increased at 24 h post-exposure. However, the endogenous proinflammatory cytokines did not contribute to METH-induced microglial cell death. On the other hand, exogenous low concentrations of TNF-α or IL-6 had a protective effect. Interestingly, we also verified that the anti-apoptotic role of TNF-α was mediated by activation of IL-6 signaling, specifically the janus kinase (JAK)-STAT3 pathway, which in turn induced down-regulation of the Bax/Bcl-2 ratio.</p> <p><b>Conclusions</b></p> <p>These findings show that TNF-α and IL-6 have a protective role against METH-induced microglial cell death via the IL-6 receptor, specifically through activation of the JAK-STAT3 pathway, with consequent changes in pro- and anti-apoptotic proteins.</p

Methyl-β-Cyclodextrins Preferentially Remove Cholesterol from the Liquid Disordered Phase in Giant Unilamellar Vesicles

Methyl-β-cyclodextrins (MβCDs) are molecules that are extensively used to remove and to load cholesterol (Chol) from artificial and natural membranes; however, the mechanism of Chol extraction by MβCD from pure lipids or from complex mixtures is not fully understood. One of the outstanding questions in this field is the capability of MβCD to remove Chol from lipid domains having different packing. Here, we investigated the specificity of MβCD to remove Chol from coexisting macrodomains with different lipid packing. We used giant unilamellar vesicles (GUVs) made of 1,2-dioleoylphosphatidylcholine:1,2-dipalmitoylphatidylcholine:free cholesterol, 1:1:1 molar ratio at 27°C. Under these conditions, individual GUVs present Chol distributed into lo and ld phases. The two phases can be distinguished and visualized using Laurdan generalized polarization and two-photon excitation fluorescence microscopy. Our data indicate that MβCD removes Chol preferentially from the more disordered phase. The process of selective Chol removal is dependent on the MβCD concentration. At high concentrations, MβCD also removes phospholipids

Factors Associated with Tuberculosis Treatment Default in an Endemic Area of the Brazilian Amazon: A Case Control-Study

SETTING: Treatment default is a serious problem in tuberculosis control because it implies persistence of infection source, increased mortality, increased relapse rates and facilitates the development of resistant strains. OBJECTIVE: This study analyzed tuberculosis treatment default determinants in the Amazonas State to contribute in planning appropriate control interventions. DESIGN: Observational study with a retrospective cohort using Brazilian Disease Notification System data from 2005 to 2010. A nested case control study design was used. Patients defaulting from treatment were considered as 'cases' and those completing treatment as 'controls'. In the analysis, 11,312 tuberculosis patients were included, 1,584 cases and 9,728 controls. RESULTS: Treatment default was observed to be associated to previous default (aOR 3.20; p<0.001), HIV positivity (aOR 1.62; p<0.001), alcoholism (aOR 1.51; p<0.001), low education level (aOR 1.35; p<0.001) and other co-morbidities (aOR 1.31; p = 0.05). Older patients (aOR 0.98; p = 0.001) and DOT (aOR 0,72; p<0.01) were considered as protective factor for default. CONCLUSIONS: Associated factors should be considered in addressing care and policy actions to tuberculosis control. Information on disease and treatment should be intensified and appropriate to the level of education of the population, in order to promote adherence to treatment and counter the spread of multidrug resistance to anti-TB drugs

Microglia Are Mediators of Borrelia burgdorferi–Induced Apoptosis in SH-SY5Y Neuronal Cells

Inflammation has long been implicated as a contributor to pathogenesis in many CNS illnesses, including Lyme neuroborreliosis. Borrelia burgdorferi is the spirochete that causes Lyme disease and it is known to potently induce the production of inflammatory mediators in a variety of cells. In experiments where B. burgdorferi was co-cultured in vitro with primary microglia, we observed robust expression and release of IL-6 and IL-8, CCL2 (MCP-1), CCL3 (MIP-1α), CCL4 (MIP-1β) and CCL5 (RANTES), but we detected no induction of microglial apoptosis. In contrast, SH-SY5Y (SY) neuroblastoma cells co-cultured with B. burgdorferi expressed negligible amounts of inflammatory mediators and also remained resistant to apoptosis. When SY cells were co-cultured with microglia and B. burgdorferi, significant neuronal apoptosis consistently occurred. Confocal microscopy imaging of these cell cultures stained for apoptosis and with cell type-specific markers confirmed that it was predominantly the SY cells that were dying. Microarray analysis demonstrated an intense microglia-mediated inflammatory response to B. burgdorferi including up-regulation in gene transcripts for TLR-2 and NFκβ. Surprisingly, a pathway that exhibited profound changes in regard to inflammatory signaling was triggering receptor expressed on myeloid cells-1 (TREM1). Significant transcript alterations in essential p53 pathway genes also occurred in SY cells cultured in the presence of microglia and B. burgdorferi, which indicated a shift from cell survival to preparation for apoptosis when compared to SY cells cultured in the presence of B. burgdorferi alone. Taken together, these findings indicate that B. burgdorferi is not directly toxic to SY cells; rather, these cells become distressed and die in the inflammatory surroundings generated by microglia through a bystander effect. If, as we hypothesized, neuronal apoptosis is the key pathogenic event in Lyme neuroborreliosis, then targeting microglial responses may be a significant therapeutic approach for the treatment of this form of Lyme disease

Do Larval Supply and Recruitment Vary among Chemosynthetic Environments of the Deep Sea?

BACKGROUND: The biological communities that inhabit chemosynthetic environments exist in an ephemeral and patchily distributed habitat with unique physicochemical properties that lead to high endemicity. Consequently, the maintenance and recovery from perturbation of the populations in these habitats is, arguably, mainly regulated by larval supply and recruitment. METHODOLOGY/PRINCIPAL FINDINGS: WE USE DATA FROM THE PUBLISHED SCIENTIFIC LITERATURE TO: (1) compare the magnitudes of and variability in larval supply and settlement and recruitment at hydrothermal vents, seeps, and whale, wood and kelp falls; (2) explore factors that affect these life history processes, when information is available; and (3) explore taxonomic affinities in the recruit assemblages of the different chemosynthetic habitats, using multivariate statistical techniques. Larval supply at vents can vary across segments by several orders of magnitude for gastropods; for bivalves, supply is similar at vents on different segments, and at cold seeps. The limited information on larval development suggests that dispersal potential may be highest for molluscs from cold seeps, intermediate for siboglinids at vents and lowest for the whale-bone siboglinid Osedax. Settlement is poorly studied and only at vents and seeps, but tends to be highest near an active source of emanating fluid in both habitats. Rate of recruitment at vents is more variable among studies within a segment than among segments. Across different chemosynthetic habitats, recruitment rate of bivalves is much more variable than that of gastropods and polychaetes. Total recruitment rate ranges only between 0.1 and 1 ind dm(-2) d(-1) across all chemosynthetic habitats, falling above rates in the non-reducing deep sea. The recruit assemblages at vents, seeps and kelp falls have lower taxonomic breadth, and include more families and genera that have many species more closely related to each other than those at whale and wood falls. Vents also have the most uneven taxonomic structure, with fewer recruits represented by higher taxonomic levels (phyla, orders, classes) compared to seeps and wood and kelp falls, whereas the opposite is true at whale falls. CONCLUSIONS/SIGNIFICANCE: Based on our evaluation of the literature, the patterns and regulatory factors of the early history processes in chemosynthetic environments in the deep sea remain poorly understood. More research focused on these early life history stages will allow us to make inferences about the ecological and biogeographic linkages among the reducing habitats in the deep sea

Hydrothermal activity, functional diversity and chemoautotrophy are major drivers of seafloor carbon cycling

Hydrothermal vents are highly dynamic ecosystems and are unusually energy rich in the deep-sea. In situ hydrothermal-based productivity combined with sinking photosynthetic organic matter in a soft-sediment setting creates geochemically diverse environments, which remain poorly studied. Here, we use comprehensive set of new and existing field observations to develop a quantitative ecosystem model of a deep-sea chemosynthetic ecosystem from the most southerly hydrothermal vent system known. We find evidence of chemosynthetic production supplementing the metazoan food web both at vent sites and elsewhere in the Bransfield Strait. Endosymbiont-bearing fauna were very important in supporting the transfer of chemosynthetic carbon into the food web, particularly to higher trophic levels. Chemosynthetic production occurred at all sites to varying degrees but was generally only a small component of the total organic matter inputs to the food web, even in the most hydrothermally active areas, owing in part to a low and patchy density of vent-endemic fauna. Differences between relative abundance of faunal functional groups, resulting from environmental variability, were clear drivers of differences in biogeochemical cycling and resulted in substantially different carbon processing patterns between habitats

Methane-carbon flow into the benthic food web at cold seeps – a case study from the Costa Rica subduction zone

Cold seep ecosystems can support enormous biomasses of free-living and symbiotic chemoautotrophic organisms that get their energy from the oxidation of methane or sulfide. Most of this biomass derives from animals that are associated with bacterial symbionts, which are able to metabolize the chemical resources provided by the seeping fluids. Often these systems also harbor dense accumulations of non-symbiotic megafauna, which can be relevant in exporting chemosynthetically fixed carbon from seeps to the surrounding deep sea. Here we investigated the carbon sources of lithodid crabs (Paralomis sp.) feeding on thiotrophic bacterial mats at an active mud volcano at the Costa Rica subduction zone. To evaluate the dietary carbon source of the crabs, we compared the microbial community in stomach contents with surface sediments covered by microbial mats. The stomach content analyses revealed a dominance of epsilonproteobacterial 16S rRNA gene sequences related to the free-living and epibiotic sulfur oxidiser Sulfurovum sp. We also found Sulfurovum sp. as well as members of the genera Arcobacter and Sulfurimonas in mat-covered surface sediments where Epsilonproteobacteria were highly abundant constituting 10% of total cells. Furthermore, we detected substantial amounts of bacterial fatty acids such as i-C15:0 and C17:1ω6c with stable carbon isotope compositions as low as −53‰ in the stomach and muscle tissue. These results indicate that the white microbial mats at Mound 12 are comprised of Epsilonproteobacteria and that microbial mat-derived carbon provides an important contribution to the crab's nutrition. In addition, our lipid analyses also suggest that the crabs feed on other 13C-depleted organic matter sources, possibly symbiotic megafauna as well as on photosynthetic carbon sources such as sedimentary detritus

Changes in grassland management and linear infrastructures associated to the decline of an endangered bird population

European grassland birds are experiencing major population declines, mainly due to changes in farmland management. We analyzed the role of habitat availability, grazing management and linear infrastructures (roads and power lines) in explaining spatial and temporal variation in the population density of little bustards (Tetrax tetrax) in Portugal, during a decade in which the species population size halved. We used data from 51 areas (totaling ca. 1,50,000 ha) that were sampled in two different periods (2003–2006 and 2016). In 2003–2006, when the species occurred at high densities, habitat availability was the only factor affecting spatial variation in bustard density. In the 2016 survey, variation in density was explained by habitat availability and livestock management, with reduced bird numbers in areas with higher proportions of cattle. Population declines across the study period were steeper in areas that initially held higher densities of bustards and in areas with a higher proportion of cattle in the total stocking rate. Areas with higher densities of power lines also registered greater density declines, probably due to avoidance behavior and to increased mortality. Overall, our results show little bustards are currently lacking high quality grassland habitat, whose persistence depends on extensive grazing regimes and low linear infrastructure densitiesinfo:eu-repo/semantics/publishedVersio

Activation of Human Monocytes by Live Borrelia burgdorferi Generates TLR2-Dependent and -Independent Responses Which Include Induction of IFN-β

It is widely believed that innate immune responses to Borrelia burgdorferi (Bb) are primarily triggered by the spirochete's outer membrane lipoproteins signaling through cell surface TLR1/2. We recently challenged this notion by demonstrating that phagocytosis of live Bb by peripheral blood mononuclear cells (PBMCs) elicited greater production of proinflammatory cytokines than did equivalent bacterial lysates. Using whole genome microarrays, we show herein that, compared to lysates, live spirochetes elicited a more intense and much broader transcriptional response involving genes associated with diverse cellular processes; among these were IFN-β and a number of interferon-stimulated genes (ISGs), which are not known to result from TLR2 signaling. Using isolated monocytes, we demonstrated that cell activation signals elicited by live Bb result from cell surface interactions and uptake and degradation of organisms within phagosomes. As with PBCMs, live Bb induced markedly greater transcription and secretion of TNF-α, IL-6, IL-10 and IL-1β in monocytes than did lysates. Secreted IL-18, which, like IL-1β, also requires cleavage by activated caspase-1, was generated only in response to live Bb. Pro-inflammatory cytokine production by TLR2-deficient murine macrophages was only moderately diminished in response to live Bb but was drastically impaired against lysates; TLR2 deficiency had no significant effect on uptake and degradation of spirochetes. As with PBMCs, live Bb was a much more potent inducer of IFN-β and ISGs in isolated monocytes than were lysates or a synthetic TLR2 agonist. Collectively, our results indicate that the enhanced innate immune responses of monocytes following phagocytosis of live Bb have both TLR2-dependent and -independent components and that the latter induce transcription of type I IFNs and ISGs