scholarly journals Single-cell visualization indicates direct role of sponge host in uptake of dissolved organic matter

2019 ◽  
Vol 286 (1916) ◽  
pp. 20192153 ◽  
Author(s):  
Michelle Achlatis ◽  
Mathieu Pernice ◽  
Kathryn Green ◽  
Jasper M. de Goeij ◽  
Paul Guagliardo ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Secondary Ion Mass Spectrometry ◽  
Physiological Mechanism ◽  
Marine Sponges ◽  
Direct Role ◽  
Transmission Electron ◽  
High Enrichment ◽  
The Individual ◽  
Near Future

Marine sponges are set to become more abundant in many near-future oligotrophic environments, where they play crucial roles in nutrient cycling. Of high importance is their mass turnover of dissolved organic matter (DOM), a heterogeneous mixture that constitutes the largest fraction of organic matter in the ocean and is recycled primarily by bacterial mediation. Little is known, however, about the mechanism that enables sponges to incorporate large quantities of DOM in their nutrition, unlike most other invertebrates. Here, we examine the cellular capacity for direct processing of DOM, and the fate of the processed matter, inside a dinoflagellate-hosting bioeroding sponge that is prominent on Indo-Pacific coral reefs. Integrating transmission electron microscopy with nanoscale secondary ion mass spectrometry, we track 15 N- and 13 C-enriched DOM over time at the individual cell level of an intact sponge holobiont. We show initial high enrichment in the filter-feeding cells of the sponge, providing visual evidence of their capacity to process DOM through pinocytosis without mediation of resident bacteria. Subsequent enrichment of the endosymbiotic dinoflagellates also suggests sharing of host nitrogenous wastes. Our results shed light on the physiological mechanism behind the ecologically important ability of sponges to cycle DOM via the recently described sponge loop.

Influence of dissolved organic matter and inorganic nutrients on the biofilm bacterial community on artificial substrates in a northeastern Ohio, USA, stream

2006 ◽  
Vol 52 (6) ◽  
pp. 540-549 ◽  
Author(s):  
Ola A Olapade ◽  
Laura G Leff
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Nutrient Dynamics ◽  
Inorganic Nutrients ◽  
Artificial Substrates ◽  
Response Patterns ◽  
Ceramic Tiles ◽  
Phylogenetic Groups ◽  
Leaf Leachate ◽  
The Individual

Stream bacteria may be influenced by the composition and availability of dissolved organic matter (DOM) and inorganic nutrients, but knowledge about how individual phylogenetic groups in biofilm are affected is still limited. In this study, the influence of DOM and inorganic nutrients on stream biofilm bacteria was examined. Biofilms were developed on artificial substrates (unglazed ceramic tiles) for 21 days in a northeastern Ohio (USA) stream for five consecutive seasons. Then, the developed biofilm assemblages were exposed, in the laboratory, to DOM (glucose, leaf leachate, and algal exudates) and inorganic nutrients (nitrate, phosphate, and nitrate and phosphate in combination) amendments for 6 days. Bacterial numbers in the biofilms were generally higher in response to the DOM treatments than to the inorganic nutrient treatments. There were also apparent seasonal variations in the response patterns of the individual bacterial taxa to the nutrient treatments; an indication that limiting resources to bacteria in stream biofilms may change over time. Overall, in contrast to the other treatments, bacterial abundance was generally highest in response to the low-molecular-weight DOM (i.e., glucose) treatment. These results further suggest that there are interactions among the different bacterial groups in biofilms that are impacted by the associated nutrient dynamics among seasons in stream ecosystems.Key words: biofilms, nutrients, DOM, bacteria, in situ hybridization.

scholarly journals Interface-dominated growth of a metastable novel alloy phase

2005 ◽  
Vol 20 (10) ◽  
pp. 2639-2646 ◽  
Author(s):  
Subhendu Sarkar ◽  
Alokmay Datta ◽  
Purushottam Chakraborty ◽  
Biswarup Satpati
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Metastable Phase ◽  
Alloy Film ◽  
Interfacial Region ◽  
Lattice Image ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Interfacial Confinement ◽  
The Individual ◽  
Almost All

A new D023 metastable phase of Cu3Au was found to grow at the interfaces of Au/Cu multilayers deposited by magnetron sputtering. The extent of formation of this novel alloy phase depends upon an optimal range of interfacial width primarily governed by the deposition wattage of the direct current magnetron used. Such interfacially confined growth is utilized to grow a ∼300-nm-thick Au/Cu multilayer with thickness of each layer nearly equal to the optimal interfacial width which was obtained from secondary-ion mass spectrometry (SIMS) data. This growth technique is observed to enhance the formation of the novel alloy phase to a considerable extent. The SIMS depth profile also indicates that the mass fragment corresponding to Cu3Au occupies the whole film while x-ray diffraction (XRD) shows almost all the strong peaks belonging to the D023 structure. High-resolution cross-sectional transmission electron microscopy shows the near-perfect growth of the individual layers and also the lattice image of the alloy phase in the interfacial region. Vacuum annealing of the alloy film and XRD studies indicate stabilization of the D023 phase at ∼150 °C. The role of interfacial confinement, the interplay between interfacial strain and free energy, and the hyperthermal species generated during the sputtering process are discussed.

scholarly journals Marine Sponges asChloroflexiHot Spots: Genomic Insights and High-Resolution Visualization of an Abundant and Diverse Symbiotic Clade

mSystems ◽  
2018 ◽  
Vol 3 (6) ◽  
Author(s):  
Kristina Bayer ◽  
Martin T. Jahn ◽  
Beate M. Slaby ◽  
Lucas Moitinho-Silva ◽  
Ute Hentschel
Keyword(s):  
Organic Matter ◽  
Amino Acid ◽  
Dissolved Organic Matter ◽  
Single Cell ◽  
Light And Electron Microscopy ◽  
Marine Sponges ◽  
Functional Gene ◽  
Gene Repertoire ◽  
Carbohydrate Degradation ◽  
Sponge Symbionts

ABSTRACTMembers of the widespread bacterial phylumChloroflexican dominate high-microbial-abundance (HMA) sponge microbiomes. In the Sponge Microbiome Project,Chloroflexisequences amounted to 20 to 30% of the total microbiome of certain HMA sponge genera with the classes/clades SAR202,Caldilineae, andAnaerolineaebeing the most prominent. We performed metagenomic and single-cell genomic analyses to elucidate the functional gene repertoire ofChloroflexisymbionts ofAplysina aerophoba. Eighteen draft genomes were reconstructed and placed into phylogenetic context of which six were investigated in detail. Common genomic features ofChloroflexisponge symbionts were related to central energy and carbon converting pathways, amino acid and fatty acid metabolism, and respiration. Clade-specific metabolic features included a massively expanded genomic repertoire for carbohydrate degradation inAnaerolineaeandCaldilineaegenomes, but only amino acid utilization by SAR202. WhileAnaerolineaeandCaldilineaeimport cofactors and vitamins, SAR202 genomes harbor genes encoding components involved in cofactor biosynthesis. A number of features relevant to symbiosis were further identified, including CRISPR-Cas systems, eukaryote-like repeat proteins, and secondary metabolite gene clusters.Chloroflexisymbionts were visualized in the sponge extracellular matrix at ultrastructural resolution by the fluorescencein situhybridization-correlative light and electron microscopy (FISH-CLEM) method. Carbohydrate degradation potential was reported previously for “CandidatusPoribacteria” and SAUL, typical symbionts of HMA sponges, and we propose here that HMA sponge symbionts collectively engage in degradation of dissolved organic matter, both labile and recalcitrant. Thus, sponge microbes may not only provide nutrients to the sponge host, but they may also contribute to dissolved organic matter (DOM) recycling and primary productivity in reef ecosystems via a pathway termed the sponge loop.IMPORTANCEChloroflexirepresent a widespread, yet enigmatic bacterial phylum with few cultivated members. We used metagenomic and single-cell genomic approaches to characterize the functional gene repertoire ofChloroflexisymbionts in marine sponges. The results of this study suggest clade-specific metabolic specialization and thatChloroflexisymbionts have the genomic potential for dissolved organic matter (DOM) degradation from seawater. Considering the abundance and dominance of sponges in many benthic environments, we predict that the role of sponge symbionts in biogeochemical cycles is larger than previously thought.

Pb uptake by the freshwater alga Chlorella kesslerii in the presence of dissolved organic matter of variable composition

2008 ◽  
Vol 5 (5) ◽  
pp. 366 ◽  
Author(s):  
Cristina Lamenas ◽  
Vera I. Slaveykova
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Traditional Approach ◽  
Complex Mixture ◽  
Ion Concentration ◽  
Variable Composition ◽  
Lead Ion ◽  
Complex Nature ◽  
Quantitative Understanding ◽  
The Individual

Environmental context. Dissolved organic matter (DOM) is of utmost importance for a toxic metal’s fate and ecotoxicity in the aquatic system, but the complex nature and variable composition of DOM makes the quantitative understanding of DOM’s role in the environment very difficult. We have demonstrated that the assumption that the properties of a DOM mixture are the sum of the properties of its individual fractions can capture the main trends characterising the role of DOM in lead speciation and adsorption by freshwater microalgae. This was done by mixing the isolated, well-characterised fractions of DOM and measuring levels of free lead ion and Pb adsorbed and internalised by algae. Abstract. Dissolved organic matter (DOM) is a complex mixture of ill-defined components, which makes the quantitative understanding of DOM functions in aquatic systems a challenging task. The traditional approach for studying such complex mixtures involves their separation into groups of different components, while assuming minimal or no alteration of their properties. By mixing the pre-isolated and well-characterised individual fractions of the DOM, including humic, fulvic and alginic acids, we have demonstrated that the free Pb ion concentrations and the adsorbed Pb plus Pb internalised by the alga Chlorella kesslerii in the presence of DOM samples of different compositions can be predicted on the basis of the experiments performed in the presence of the individual DOM fractions. An additivity model assuming that the properties of the mixture can be considered as the sum of the properties of the individual components captured the Pb speciation and adsorption behaviour in the presence of DOM of variable compositions. Similarly to the results with the individual DOM fractions, internalised Pb concentrations in the presence of the reconstituted DOM were greater than that predicted by the corresponding free lead ion concentration. An improved fit between experimental observations and the model predictions of adsorbed plus internalised Pb in the presence of DOM of different compositions was observed by assuming that each individual component adsorbed by the algae gave access to additional binding sites for Pb. Furthermore, the contribution of the Pb–DOM complex to total cellular Pb was dominated by the humic and fulvic acids, whereas the contribution of alginate was minimal.

scholarly journals Demographic consequences of mitigating strategies in planktonic invertebrates facing global browning of freshwater ecosystem

2021 ◽  
Vol 83 (2) ◽  
Author(s):  
Małgorzata Adamczuk
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Current Knowledge ◽  
Temporal Stability ◽  
Resting Eggs ◽  
Community Level ◽  
Freshwater Ecosystem ◽  
Freshwater Invertebrates ◽  
Chydorus Sphaericus ◽  
The Individual

AbstractRecently, it has been reported that freshwater browning has less effect on planktonic invertebrate abundances than would be expected from current knowledge regarding of the biochemical activity of dissolved organic matter. It may be that the weak responses of whole communities to browning are masked because the individual mitigating strategies of community components have disparate demographic consequences. To examine the above hypothesis, individual-, population- and community-level responses of freshwater invertebrates to varying concentrations of terrestrial dissolved organic matter (tDOM) were investigated. Common cladocerans of the Chydoridae family, Chydorus sphaericus and Acroperus harpae, were used in the experiment which revealed that species employed different strategies to cope with tDOM. C. sphaericus maintained high production of asexual offspring at the cost of individual body growth, so any decreases in the population sizes were not observed. A. harpae, conversely, invested mainly in the production of resting eggs and increased survivability, which resulted in smaller populations. Invertebrate communities showed similar resilience and temporal stability across tDOM concentrations. Therefore, the influence of tDOM was apparently negligible at community level, since the effects of the mitigating strategies of the two species complemented one another. This experiment showed that symptoms of freshwater browning might be difficult to observe at population and community level due to effective mitigating strategies performed at the level of individuals. The effects of browning on freshwater invertebrates might be better considered in the context of alterations in the demographic rates together constituting life-cycle strategies to maintain species survival.

Recent developments in automated Transmission Electron MI

1989 ◽  
Vol 47 ◽  
pp. 46-47
Author(s):  
W.J. de Ruijter ◽  
P. Rez ◽  
David J. Smith
Keyword(s):  
Image Analysis ◽  
Computer Image ◽  
Lens Design ◽  
Computer Image Analysis ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Recent Developments ◽  
On Line ◽  
Routine Procedures ◽  
Near Future

There is growing interest in the on-line use of computers in high-resolution electron n which should reduce the demands on highly skilled operators and thereby extend the r of the technique. An on-line computer could obviously perform routine procedures hand, or else facilitate automation of various restoration, reconstruction and enhan These techniques are slow and cumbersome at present because of the need for cai micrographs and off-line processing. In low resolution microscopy (most biologic; primary incentive for automation and computer image analysis is to create a instrument, with standard programmed procedures. In HREM (materials researc computer image analysis should lead to better utilization of the microscope. Instru (improved lens design and higher accelerating voltages) have improved the interpretab the level of atomic dimensions (approximately 1.6 Å) and instrumental resolutior should become feasible in the near future.

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