1,721,034 research outputs found
Coupling metabolite flux to transcriptomics: insights into the molecular mechanisms underlying primary productivity by the hydrothermal vent tubeworm Ridgeia piscesae
No full textDeep-sea hydrothermal vents host highly productive ecosystems. Many of these communities are dominated by vestimentiferan tubeworms that house endosymbiotic chemoautotrophic bacteria that provide the hosts with their primary nutritional needs. Rates of carbon fixation by these symbioses are also among the highest recorded. Despite the breadth of physiological and biochemical research on these associations, the underlying molecular mechanisms that regulate host and symbiont metabolite flux and carbon fixation are largely unknown. Here we present metabolite flux and transcriptomics data from shipboard high-pressure respirometry experiments in which we maintained Ridgeia piscesae tubeworms at conditions comparable to those in situ. Host trophosome was used for cDNA library construction and sequencing. Of the 19,132 clones sequenced, 10,684 represented unique expressed sequence tags (ESTs). The highest proportions of genes are involved with translation, ribosomal structure and biogenesis, cellular processing, and signal transduction. There was moderate representation of genes involved in metabolite exchange and acid-base regulation. These data represent the first concomitant surveys of metabolite flux rates and gene expression for a chemoautotrophic symbiosis during net autotrophy, and they suggest that-in the case of Ridgeia piscesae-host-symbiont interactions such as cell cycle regulation may play a significant role in maintaining physiological poise during high productivity
Linking Hydrothermal Geochemistry to Organismal Physiology: Physiological Versatility in Riftia pachyptila from Sedimented and Basalt-hosted Vents
Full text linkMuch of what is known regarding Riftia pachyptila physiology is based on the wealth of studies of tubeworms living at diffuse flows along the fast-spreading, basalt-hosted East Pacific Rise (EPR). These studies have collectively suggested that Riftia pachyptila and its chemoautotrophic symbionts are physiologically specialized, highly productive associations relying on hydrogen sulfide and oxygen to generate energy for carbon fixation, and the symbiont's nitrate reduction to ammonia for energy and biosynthesis. However, Riftia also flourish in sediment-hosted vents, which are markedly different in geochemistry than basalt-hosted systems. Here we present data from shipboard physiological studies and global quantitative proteomic analyses of Riftia pachyptila trophosome tissue recovered from tubeworms residing in the EPR and the Guaymas basin, a sedimented, hydrothermal vent field. We observed marked differences in symbiont nitrogen metabolism in both the respirometric and proteomic data. The proteomic data further suggest that Riftia associations in Guaymas may utilize different sulfur compounds for energy generation, may have an increased capacity for energy storage, and may play a role in degrading exogenous organic carbon. Together these data reveal that Riftia symbionts are far more physiologically plastic than previously considered, and that -contrary to previous assertions- Riftia do assimilate reduced nitrogen in some habitats. These observations raise new hypotheses regarding adaptations to the geochemical diversity of habitats occupied by Riftia, and the degree to which the environment influences symbiont physiology and evolution.Organismic and Evolutionary BiologyVersion of Recor
Characterizing microbial community and geochemical dynamics at hydrothermal vents using osmotically-driven continuous fluid samplers
No full textMicrobes play a key role in mediating aquatic biogeochemical cycles. However, our understanding of the relationships between microbial phylogenetic/physiological diversity and habitat physicochemical characteristics is restrained by our limited capacity to concurrently collect microbial and geochemical samples at appropriate spatial and temporal scales. Accordingly, we have developed a low-cost, continuous fluid sampling system (the Biological OsmoSampling System, or BOSS) to address this limitation. The BOSS does not use electricity, can be deployed in harsh/remote environments, and collects/preserves samples with daily resolution for >1 year. Here, we present data on the efficacy of DNA and protein preservation during a 1.5 year laboratory study as well as the results of two field deployments at deep-sea hydrothermal vents, wherein we examined changes in microbial diversity, protein expression, and geochemistry over time. Our data reveal marked changes in microbial composition co-occurring with changes in hydrothermal fluid composition as well as the temporal dynamics of an enigmatic sulfide-oxidizing symbiont in its free-living state. We also present the first data on in situ protein preservation and expression dynamics highlighting the BOSS’s potential utility in meta-proteomic studies. These data illustrate the value of using BOSS to study relationships among microbial and geochemical phenomena and environmental conditions
Environmental parameters of deep-sea hydrothermal vents from the Manus Basin
No full textThirtythree diffuse fluid and water column samples and 23 samples from surfaces of chimneys, rocks and fauna were subjected to a combined analyses of 16S rRNA gene sequences, metagenomes and real-time in situ measured geochemical parameters to study distribution and niche-partitioning of sulfur-oxidizing bacteria (SOB) in deep-sea hydrothermal environments of the Manus Basin, a back-arc fast-spreading center located between New Britain and New Ireland in the Bismarck Sea.
High throughput 16S rRNA gene amplicon sequences obtained by Illumina paired-end sequencing using the primer combination Bakt_341F and Bakt_805R for all samples were analyzed as well as full-length 16S rRNA genes using a Pacific Biosciences RSII sequencer. Additionally, 5 metagenomes were sequenced (Illumina HiSeq 2500, paired-end shotgun), assembled, binned, and re-binned, resulting in 11 Sulfurovum-related, 5 Sulfurimonas-related and 12 SUP05-clade bins. These bins were analyzed with respect to genomic variability among hydrothermal vent SOB and especially with respect to the differentiation of their sulfur oxidation genes.
Correlating distribution patterns to real-time geochemical data, tentative niches could be assigned to key hydrothermal SOB clades: Sulfurovum Epsilonproteobacteria were mainly found attached to surfaces exposed to diffuse venting, while the SUP05-clade dominated the bacterioplankton in highly diluted mixtures of vent fluids and seawater. The high diversity within Sulfurimonas- and Sulfurovum-related Epsilonproteobacteria observed in this study was proposed to be derived from the high variation of environmental parameters such as oxygen and sulfide concentrations across small spatial and temporal scales
Sulfur bacteria promote dissolution of authigenic carbonates at marine methane seeps
No full textAssembled 16S rRNA gene iTag libraries of the microbial communities attached to a methane seep carbonate rock on the top surfaces vs. the bottom surface (in contact with sediments) subsampled 3 times.Carbonate rocks at marine methane seeps are commonly colonized by sulfur-oxidizing bacteria that co-occur with etch pits that suggest active dissolution. We show that sulfur-oxidizing bacteria are abundant on the surface of an exemplar seep carbonate collected from Del Mar East Methane Seep Field, USA. We then used bioreactors containing aragonite mineral coupons that simulate certain seep conditions to investigate plausible in situ rates of carbonate dissolution associated with sulfur-oxidizing bacteria. Bioreactors inoculated with a sulfur-oxidizing bacterial strain, Celeribacter baekdonensis LH4, growing on aragonite coupons induced dissolution rates in sulfidic, heterotrophic, and abiotic conditions of 1773.97 (±324.35), 152.81 (±123.27), and 272.99 (±249.96) Mol CaCO3 cm-2 yr-1, respectively. Steep gradients in pH were also measured within carbonate-attached biofilms using pH-sensitive fluorophores. Together, these results show that the production of acidic microenvironments in biofilms of sulfur-oxidizing bacteria are capable of dissolving carbonate rocks, even under well-buffered marine conditions. Our results support the hypothesis that authigenic carbonate rock dissolution driven by lithotrophic sulfur-oxidation constitutes a previously unknown carbon flux from the rock reservoir to the ocean and atmosphere.NASA Exobiology (NNX-14AK20G)NSF (OCE-0826254)NASA (80NSSC18K1140)NSF (1542506)Leprich, Dalton J.; Flood, Beverly E.; Schroedl, Peter R.; Ricci, Elizabeth; Marlow, Jeffery J.; Girguis, Peter R.; Bailey, Jake V.. (2021). Sulfur bacteria promote dissolution of authigenic carbonates at marine methane seeps. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/4j4t-e569
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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Physiological Investigations into Environmental Stress Response in the Hydrothermal Vent Polychaete Paralvinella sulfincola
Full text linkThe most universal abiotic influence is temperature, and thus, thermotolerance, adaptations and response to thermal variation, is a fundamental factor shaping evolution. Prokaryotic life may have an upper thermal limit near ; however, eukaryotic survival is limited to – the thermal maximum for sustained biosynthesis and homeostasis. My research focuses on understanding the physiological and biochemical factors that limit eukaryotic thermotolerance, by studying an organism near the upper limit of all eukaryotes: Paralvinella sulfincola. P. sulfincola, a hydrothermal vent polychaete, has the broadest known thermal range of any metazoan: . This species, along with the mesotolerant congener with Paralvinella palmiformis, is found at vents along the Juan de Fuca Ridge, Washington, USA. Making an ideal study system, both species are found in similar habitats, genetically comparable, and amenable to recovery and shipboard experimentation. Here, I present data from a series of high pressure in vivo experiments that investigate stress response to variations in temperature, pH, sulfide concentration, and duration. Field work was coupled with a suite of biomolecular techniques including pyrosequencing, comparative proteomics, enzyme assays, and quantitative PCR. From this research, the first to quantify global protein and antioxidant responses to temperature in an extremely thermotolerant eukaryote, three primary conclusions can be reached. 1) Pronounced thermal tolerance in P. sulfincola is likely enabled by its constitutive expression of heat shock proteins and limited by its ability to quickly and appropriately respond to the commensurate increase in oxidative stress. 2) Thermal tolerance limits are likely negatively affected by synergistic multistress effects. 3) Antioxidant gene expression response differs significantly between chronically and acutely stressed treatments, supporting the theory that oxidative stress is limiting in this system
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Microbe-electrode interactions: The chemico-physical environment and electron transfer
Full text linkThis thesis presents studies that examine microbial extracellular electron transfer that an emphasis characterizing how environmental conditions influence electron flux between microbes and a solid-phase electron donor or acceptor. I used bioelectrochemical systems (BESs), fluorescence and electron microscopy, chemical measurements, 16S rRNA analysis, and qRT-PCR to study these relationships among chemical, physical and biological parameters and processes.Engineering and Applied Science
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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