Sulfide acquisition by the vent worm Riftia pachyptila appears to be via uptake of HS-, rather than H2S.

1997 ◽  
Vol 200 (20) ◽  
pp. 2609-2616
Author(s):  
S K Goffredi ◽  
J J Childress ◽  
N T Desaulniers ◽  
F J Lallier
Keyword(s):  
Hydrothermal Vents ◽  
Carbon Fixation ◽  
Extracellular Fluid ◽  
High Growth ◽  
Riftia Pachyptila ◽  
Sulfide Toxicity ◽  
Sulfide Inhibition ◽  
Chemosynthetic Bacteria ◽  
Preferential Uptake ◽  
Very High

Deep-sea hydrothermal vents are home to a variety of invertebrate species, many of which host chemosynthetic bacteria in unusual symbiotic arrangements. The vent tubeworm Riftia pachyptila (Vestimentifera) relies upon internal chemolithoautotrophic bacterial symbionts to support its large size and high growth rates. Because of this, R. pachyptila must supply sulfide to the bacteria, which are far removed from the external medium. Internal H2S ([H2S+HS-+S2-]) can reach very high levels in R. pachyptila (2-12mmoll-1 in the vascular blood), most of which is bound to extracellular hemoglobins. The animal can potentially take up sulfide from the environment via H2S diffusion or via mediated uptake of HS-, or both. It was expected that H2S diffusion would be the primary sulfide acquisition mechanism, paralleling the previously demonstrated preferential uptake of CO2. Our data show, however, that the uptake of HS- is the primary mechanism used by R. pachyptila to obtain sulfide and that H2S diffusion into the worm apparently proceeds at a much slower rate than expected. This unusual mechanism may have evolved because HS- is less toxic than H2S and because HS- uptake decouples sulfide and inorganic carbon acquisition. The latter occurs via the diffusion of CO2 at very high rates due to the maintenance of an alkaline extracellular fluid pH. H2S accumulation is limited, however, to sulfide that can be bound by the hemoglobins, protecting the animal from sulfide toxicity and the symbionts from sulfide inhibition of carbon fixation.

scholarly journals Inorganic carbon acquisition by the hydrothermal vent tubeworm Riftia pachyptila depends upon high external PCO2 and upon proton-equivalent ion transport by the worm

1997 ◽  
Vol 200 (5) ◽  
pp. 883-896 ◽  
Author(s):  
S Goffredi ◽  
J Childress ◽  
N Desaulniers ◽  
R Lee ◽  
F Lallier ◽  
...  
Keyword(s):  
Ion Transport ◽  
Body Fluid ◽  
Hydrothermal Vents ◽  
Inorganic Carbon ◽  
Extracellular Fluid ◽  
High Growth ◽  
Extracellular Ph ◽  
Elevated Pco2 ◽  
Riftia Pachyptila ◽  
Atpase Inhibitor

Riftia pachyptila is the most conspicuous organism living at deep sea hydrothermal vents along the East Pacific Rise. To support its large size and high growth rates, this invertebrate relies exclusively upon internal chemosynthetic bacterial symbionts. The animal must supply inorganic carbon at high rates to the bacteria, which are far removed from the external medium. We found substantial differences in body fluid total inorganic carbon (CO2) both within and between vent sites when comparing freshly captured worms from a variety of places. However, the primary influence on body fluid CO2 was the chemical characteristics of the site from which the worms were collected. Studies on tubeworms, both freshly captured and maintained in captivity, demonstrate that the acquisition of inorganic carbon is apparently limited by the availability of CO2, as opposed to bicarbonate, and thus appears to be accomplished via diffusion of CO2 into the plume, rather than by mediated transport of bicarbonate. The greatly elevated PCO2 measured at the vent sites (up to 12.6 kPa around the tubeworms), which is a result of low environmental pH (as low as 5.6 around the tubeworms), and elevated CO2 (as high as 7.1 mmol l-1 around the tubes) speeds this diffusion. Moreover, despite large and variable amounts of internal CO2, these worms maintain their extracellular fluid pH stable, and alkaline, in comparison with the environment. The maintenance of this alkaline pH acts to concentrate inorganic carbon into extracellular fluids. Exposure to N-ethylmaleimide, a non-specific H+-ATPase inhibitor, appeared to stop this process, resulting in a decline in extracellular pH and CO2. We hypothesize that the worms maintain their extracellular pH by active proton-equivalent ion transport via high concentrations of H+-ATPases. Thus, Riftia pachyptila is able to support its symbionts' large demand for inorganic carbon owing to the elevated PCO2 in the vent environment and because of its ability to control its extracellular pH in the presence of large inward CO2 fluxes.

scholarly journals Host–Endosymbiont Genome Integration in a Deep-Sea Chemosymbiotic Clam

2020 ◽  
Author(s):  
Jack Chi-Ho Ip ◽  
Ting Xu ◽  
Jin Sun ◽  
Runsheng Li ◽  
Chong Chen ◽  
...  
Keyword(s):  
Deep Sea ◽  
Hydrothermal Vents ◽  
Carbon Fixation ◽  
Sulfur Oxidation ◽  
Gene Families ◽  
Cold Seeps ◽  
Cellular Processes ◽  
Metabolic Integration ◽  
Metabolite Exchange ◽  
Chemosynthetic Bacteria

Abstract Endosymbiosis with chemosynthetic bacteria has enabled many deep-sea invertebrates to thrive at hydrothermal vents and cold seeps, but most previous studies on this mutualism have focused on the bacteria only. Vesicomyid clams dominate global deep-sea chemosynthesis-based ecosystems. They differ from most deep-sea symbiotic animals in passing their symbionts from parent to offspring, enabling intricate coevolution between the host and the symbiont. Here, we sequenced the genomes of the clam Archivesica marissinica (Bivalvia: Vesicomyidae) and its bacterial symbiont to understand the genomic/metabolic integration behind this symbiosis. At 1.52 Gb, the clam genome encodes 28 genes horizontally transferred from bacteria, a large number of pseudogenes and transposable elements whose massive expansion corresponded to the timing of the rise and subsequent divergence of symbiont-bearing vesicomyids. The genome exhibits gene family expansion in cellular processes that likely facilitate chemoautotrophy, including gas delivery to support energy and carbon production, metabolite exchange with the symbiont, and regulation of the bacteriocyte population. Contraction in cellulase genes is likely adaptive to the shift from phytoplankton-derived to bacteria-based food. It also shows contraction in bacterial recognition gene families, indicative of suppressed immune response to the endosymbiont. The gammaproteobacterium endosymbiont has a reduced genome of 1.03 Mb but retains complete pathways for sulfur oxidation, carbon fixation, and biosynthesis of 20 common amino acids, indicating the host’s high dependence on the symbiont for nutrition. Overall, the host–symbiont genomes show not only tight metabolic complementarity but also distinct signatures of coevolution allowing the vesicomyids to thrive in chemosynthesis-based ecosystems.

Very High Growth Rate of 4H-SiC Using MTS as Chloride-Based Precursor

2008 ◽  
Vol 600-603 ◽  
pp. 115-118 ◽  
Author(s):  
Henrik Pedersen ◽  
Stefano Leone ◽  
Anne Henry ◽  
Franziska Christine Beyer ◽  
Vanya Darakchieva ◽  
...  
Keyword(s):  
Growth Rate ◽  
Linear Dependence ◽  
Growth Rates ◽  
Molar Fraction ◽  
High Growth ◽  
High Growth Rate ◽  
Epitaxial Layers ◽  
Single Precursor ◽  
Very High

The chlorinated precursor methyltrichlorosilane (MTS), CH3SiCl3, has been used to grow epitaxial layers of 4H-SiC in a hot wall CVD reactor, with growth rates as high as 170 µm/h at 1600°C. Since MTS contains both silicon and carbon, with the C/Si ratio 1, MTS was used both as single precursor and mixed with silane or ethylene to study the effect of the C/Si and Cl/Si ratios on growth rate and doping of the epitaxial layers. When using only MTS as precursor, the growth rate showed a linear dependence on the MTS molar fraction in the reactor up to about 100 µm/h. The growth rate dropped for C/Si < 1 but was constant for C/Si > 1. Further, the growth rate decreased with lower Cl/Si ratio.

scholarly journals Niche partitioning in the Rimicaris exoculata holobiont: the case of the first symbiotic Zetaproteobacteria

Microbiome ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Marie-Anne Cambon-Bonavita ◽  
Johanne Aubé ◽  
Valérie Cueff-Gauchard ◽  
Julie Reveillaud
Keyword(s):  
Hydrothermal Vents ◽  
Carbon Fixation ◽  
Iron Sulfide ◽  
Hydrogen Oxidation ◽  
Niche Partitioning ◽  
Sulfur Oxidation ◽  
Single Copy ◽  
Trophic Levels ◽  
Rimicaris Exoculata ◽  
Close Relatives

Abstract Background Free-living and symbiotic chemosynthetic microbial communities support primary production and higher trophic levels in deep-sea hydrothermal vents. The shrimp Rimicaris exoculata, which dominates animal communities along the Mid-Atlantic Ridge, houses a complex bacterial community in its enlarged cephalothorax. The dominant bacteria present are from the taxonomic groups Campylobacteria, Desulfobulbia (formerly Deltaproteobacteria), Alphaproteobacteria, Gammaproteobacteria, and some recently discovered iron oxyhydroxide-coated Zetaproteobacteria. This epibiotic consortium uses iron, sulfide, methane, and hydrogen as energy sources. Here, we generated shotgun metagenomes from Rimicaris exoculata cephalothoracic epibiotic communities to reconstruct and investigate symbiotic genomes. We collected specimens from three geochemically contrasted vent fields, TAG, Rainbow, and Snake Pit, to unravel the specificity, variability, and adaptation of Rimicaris–microbe associations. Results Our data enabled us to reconstruct 49 metagenome-assembled genomes (MAGs) from the TAG and Rainbow vent fields, including 16 with more than 90% completion and less than 5% contamination based on single copy core genes. These MAGs belonged to the dominant Campylobacteria, Desulfobulbia, Thiotrichaceae, and some novel candidate phyla radiation (CPR) lineages. In addition, most importantly, two MAGs in our collection were affiliated to Zetaproteobacteria and had no close relatives (average nucleotide identity ANI < 77% with the closest relative Ghiorsea bivora isolated from TAG, and 88% with each other), suggesting potential novel species. Genes for Calvin-Benson Bassham (CBB) carbon fixation, iron, and sulfur oxidation, as well as nitrate reduction, occurred in both MAGs. However, genes for hydrogen oxidation and multicopper oxidases occurred in one MAG only, suggesting shared and specific potential functions for these two novel Zetaproteobacteria symbiotic lineages. Overall, we observed highly similar symbionts co-existing in a single shrimp at both the basaltic TAG and ultramafic Rainbow vent sites. Nevertheless, further examination of the seeming functional redundancy among these epibionts revealed important differences. Conclusion These data highlight microniche partitioning in the Rimicaris holobiont and support recent studies showing that functional diversity enables multiple symbiont strains to coexist in animals colonizing hydrothermal vents.

scholarly journals Vegetative growth of grasslands based on hyper-temporal NDVI data from the Modis sensor

2016 ◽  
Vol 51 (7) ◽  
pp. 858-868
Author(s):  
Marcos Cicarini Hott ◽  
Luis Marcelo Tavares de Carvalho ◽  
Mauro Antonio Homem Antunes ◽  
Polyanne Aguiar dos Santos ◽  
Tássia Borges Arantes ◽  
...  
Keyword(s):  
Vegetative Growth ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
High Growth ◽  
Growth Index ◽  
Data Series ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Very High

Abstract: The objective of this work was to analyze the development of grasslands in Zona da Mata, in the state of Minas Gerais, Brazil, between 2000 and 2013, using a parameter based on the growth index of the normalized difference vegetation index (NDVI) from the moderate resolution imaging spectroradiometer (Modis) data series. Based on temporal NDVI profiles, which were used as indicators of edaphoclimatic conditions, the growth index (GI) was estimated for 16-day periods throughout the spring season of 2012 to early 2013, being compared with the average GI from 2000 to 2011, used as the reference period. Currently, the grassland areas in Zona da Mata occupy approximately 1.2 million hectares. According to the used methods, 177,322 ha (14.61%) of these grassland areas have very low vegetative growth; 577,698 ha (45.96%) have low growth; 433,475 ha (35.72%) have balanced growth; 39,980 ha (3.29%) have high growth; and 5,032 ha (0.41%) have very high vegetative growth. The grasslands had predominantly low vegetative growth during the studied period, and the NDVI/Modis series is a useful source of data for regional assessments.

scholarly journals E-Service Quality dan E-Promotion Terhadap Keputusan Pembelian Konsumen pada Website Traveloka.com

Competitive ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 106-114
Author(s):  
Aditia Sovia Pramudita ◽  
Rahayu Eka Agustia
Keyword(s):  
Service Quality ◽  
Descriptive Analysis ◽  
Linear Regression Analysis ◽  
High Growth ◽  
Multiple Linear Regression Analysis ◽  
High Growth Rate ◽  
Purchasing Decisions ◽  
Quantitative Design ◽  
Service Purchasing ◽  
Very High

E-Commerce has a very high growth rate which the needs of quickly and precisely are the main target in the e-commerce business. This study aims to determine how consumers respond to the implementation of e-service quality website, e-promotion website which leads into consumer purchasing decisions at Traveloka using a descriptive quantitative design with data collection techniques through a questionnaire. The method used in this research is descriptive analysis and multiple linear regression analysis. The results show that the effect of website e-service quality and website e-promotion on service purchasing decisions at Traveloka is positive and significant. The influence of e-service quality website and e-promotion website on purchasing decisions at Traveloka is 23%. While the rest is influenced by variables not included in this study.

Cycles, Compartments, and Polymerization

2019 ◽  
Author(s):  
David W. Deamer
Keyword(s):  
Genetic Information ◽  
Hydrothermal Vents ◽  
Carbon Fixation ◽  
Energy Sources ◽  
Hydrothermal Conditions ◽  
Biologically Relevant ◽  
Cellular Life ◽  
Primitive Metabolism ◽  
Chain Lengths ◽  
Design Experiments

The two quotes in the epigraph, in juxtaposition, always make me smile, and I tried to keep them in mind while writing this chapter. The first eight chapters of this book have the effect of eliminating the impossible by investigating the facts to which Twain is referring. Perhaps he would consider them trifling, but I doubt that Twain ever performed an experiment to test an idea. Every working scientist knows that science is not just a set of facts but is also a set of questions. The best way to begin answering a question is to pose a hypothesis and that hypothesis begins as a conjecture. Only when we have a hypothesis, can we design experiments to test it, and if we are lucky, the results of those experiments lead us a little closer to the truth. This chapter summarizes facts that lead to an alternative scenario for life’s origin in freshwater hydrothermal conditions rather than a marine origin in saltwater hydrothermal vents. As stated in the introduction to this book, when assumptions are part of the story they will be made explicit so that the logic that arises from them will be clear. What follows in this overview is a list of ten prerequisites we assume are necessary for cellular life to begin, followed by eight assumptions underlying the scenario to be presented here. Prerequisite conditions for life to begin: Dilute solutions of potential reactants are available, together with a process by which they can be sufficiently concentrated to react. Energy sources available in the environment can drive reactions such as carbon fixation, primitive metabolism, and polymerization. Products of reactions accumulate within the site rather than dispersing into the bulk phase environment. Amphiphiles assemble into membranous compartments over the range of temperatures, salt concentrations, and pH values related to each site. Biologically relevant polymers are synthesized with chain lengths sufficient to act as catalysts or incorporate genetic information. A plausible physical mechanism can produce encapsulated polymers as protocells then subject them to combinatorial selection. Organic solutes in aqueous solutions become biochemical solutes within protocells and then substrates supporting a primitive metabolism.

scholarly journals Probing rapid carbon fixation in fast-growing seaweed Ulva meridionalis using stable isotope 13C-labelling

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shuntaro Tsubaki ◽  
Hiroshi Nishimura ◽  
Tomoya Imai ◽  
Ayumu Onda ◽  
Masanori Hiraoka
Keyword(s):  
Mass Spectrometry ◽  
Stable Isotope ◽  
Carbon Fixation ◽  
High Growth ◽  
Gas Chromatography Mass Spectrometry ◽  
Ion Cyclotron Resonance ◽  
Stable Isotope Labelling ◽  
Ft Icr Ms ◽  
Ft Icr ◽  
C Nmr

AbstractThe high growth rate of Ulva seaweeds makes it a potential algal biomass resource. In particular, Ulva meridionalis grows up to fourfold a day. Here, we demonstrated strong carbon fixation by U. meridionalis using 13C stable isotope labelling and traced the 13C flux through sugar metabolites with isotope-ratio mass spectrometry (IR-MS), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), 13C-nuclear magnetic resonance spectrometry (13C-NMR), and gas chromatography-mass spectrometry (GC–MS). U. meridionalis was first cultured in 13C-labelled enriched artificial seawater for 0–12 h, and the algae were collected every 4 h. U. meridionalis grew 1.8-fold (dry weight), and the 13C ratio reached 40% in 12 h, whereas 13C incorporation hardly occurred under darkness. At the beginning of the light period, 13C was incorporated into nucleic diphosphate (NDP) sugars in 4 h, and 13C labelled peaks were identified using FT-ICR-MS spectra. Using semiquantitative 13C-NMR measurements and GC–MS, 13C was detected in starch and matrix polysaccharides after the formation of NDP sugars. Moreover, the 14:10 light:dark regime resulted into 85% of 13C labelling was achieved after 72 h of cultivation. The rapid 13C uptake by U. meridionalis shows its strong carbon fixation capacity as a promising seaweed biomass feedstock.

How to optimize lichen relative growth rates in growth cabinets

2016 ◽  
Vol 48 (4) ◽  
pp. 305-310 ◽  
Author(s):  
Yngvar GAUSLAA ◽  
Md Azharul ALAM ◽  
Knut Asbjørn SOLHAUG
Keyword(s):  
Surface Water ◽  
Growth Rates ◽  
Filter Paper ◽  
High Growth ◽  
Growth Chamber ◽  
Lobaria Pulmonaria ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Very High

AbstractIn order to improve growth chamber protocols for lichens, we tested the effect of 1) wet filter paper versus self-drained nets as a substratum for lichens, and 2) gradual versus abrupt transitions between dark and light periods. For Lobaria pulmonaria (L.) Hoffm. cultivated on nets, RGR increased by 60% compared to those on wet papers, whereas abrupt on/off transitions between day/night gave as high growth rates as gradual transitions mimicking sunrise/sunset. Because thalli on nets had less surface water than those on papers, the higher RGR on nets likely resulted from less suprasaturation depression of photosynthesis. By supporting very high growth and eliminating any visible damage, the revised growth chamber protocols facilitate new functional lichen studies.

scholarly journals Revealing their innermost secrets: an evolutionary perspective on the disparity of the organ systems in anomuran crabs (Crustacea: Decapoda: Anomura)

2016 ◽  
Vol 85 (4) ◽  
pp. 361-386 ◽  
Author(s):  
Jonas Keiler ◽  
Stefan Richter ◽  
Christian S. Wirkner
Keyword(s):  
Hydrothermal Vents ◽  
Morphological Changes ◽  
Direct Consequence ◽  
Morphological Characters ◽  
Last Common Ancestor ◽  
Organ Systems ◽  
Freshwater Habitats ◽  
Chemosynthetic Bacteria ◽  
Cladistic Analyses ◽  
Morphological Transformations

The Southern Australian crustacean species Lomis hirta (Lomisoidea: Lomisidae) is a representative of one of the three anomuran taxa which obtained their crab-like habitus independently from each other. This process, the evolutionary transformation into a crab-like form, is termed carcinization. To shed light on the morphological changes which took place during carcinization and to investigate structural dependence (coherence) between external and internal morphological characters, we studied L. hirta and representatives of its putatively most closely related taxa, Aegla cholchol (Aegloidea: Aeglidae) and Kiwa puravida (Chirostyloidea: Kiwaidae). External and internal anatomy was studied using microcomputertomography and computer-aided 3D reconstruction. A. cholchol and K. puravida belong to equally exceptional lineages: Aegla is endemic to South America and lives in freshwater habitats; Kiwa is a deep sea dweller associated to chemosynthetic bacteria found in methane seeps or hydrothermal vents. On the basis of recent cladistic analyses we reconstruct the anatomical ground pattern of the squat lobster-like last common ancestor of the three taxa and trace the morphological transformations that affected inner and outer morphology in the recent forms. Our results show, among other things, that the pleon in Lomis underwent drastic modifications in the context of carcinization, including a reduction of the muscular portion leaving more room for the hepatopancreas and gonads, and a narrowing of the pleonal ganglia which became shifted anteriorly into the cephalothorax and attached to the cephalothoracic ganglion. We interpret these anatomical changes in Lomis to have come about because of the loss of the caridoid escape reaction, which in turn was a direct consequence of the evolution of a strongly bent pleon as part of the crab-like habitus, and of a hidden lifestyle.

Sign in / Sign up

Export Citation Format

Share Document