SIZE-REACTIVITY OF DISSOLVED ORGANIC MATTER IN THE CAPE VERDE FRONTAL ZONE

Oral communicationDissolved organic matter (DOM) plays a major role in the recycling, export and sequestration of biogenic organic carbon, being a key component of ocean biogeochemical cycles and of the biological and microbial carbon pumps. Microbial degradation of DOM not only produces CO 2 but also generates dissolved molecules of decreasing bioavailability that can accumulate in the oceans for hundreds to thousands of years. The size-reactivity continuum (SRC) model is the conceptual framework to explain the DOM reactivity on a size basis, although field tests are still scarce and some of the pieces of this puzzle remain unclear. Taking advantage of the FLUXES-I cruise in the Cape Verde Frontal Zone (CVFZ), we have studied the size fractionated reactivity of the high (HMW; >1 KDa) and low (LMW; <1 KDa) molecular weight fractions of the DOM from surface down to 4000 m, using a high-efficiency and low-concentration-factor ultrafiltration cell. The wide ageing range covered by the water masses of the CVFZ makes it an excellent site to test the SRC model. Regarding the bulk C and N pools, the water masses with higher oxygen utilization were more depleted in HMW molecules, with a significant preference for the degradation of large N-containing compounds. Accordingly, preferential degradation of HMW fluorescent protein-like compounds was observed. In parallel, fluorescent humic-like compounds of both HMW and LMW were generated as by-product of the degradation of HMW organic compounds, and the remineralization of the DOM increases the aromaticy of both fractions, but especially the LMW one.ASL

Threading Through Macrocycles Enhances the Performance of Carbon Nanotubes as Polymer Fillers

In this work we study the reinforcement of polymers by mechanically interlocked derivatives of single-walled carbon nanotubes (SWNTs). We compare the mechanical properties of fibers made of polymers and of composites with pristine single-walled carbon nanotubes (SWNTs), mechanically interlocked derivatives of SWNTs (MINTs) and the corresponding supramolecular models. Improvements of both Young's modulus and tensile strength of up to 200 % were observed for the polystyrene-MINTs samples with an optimized loading of just 0.01 wt.%, while the supramolecular models with identical chemical composition and loading showed negligible or even detrimental influence. This behavior is found for three different types of SWNTs and two types of macrocycles. Molecular dynamics simulations show that the polymer adopts an elongated conformation parallel to the SWNT when interacting with MINT fillers, irrespective of the macrocycle chemical nature, whereas a more globular structure is taken upon facing with either pristine SWNTs or supramolecular models. The MINT composite architecture thus leads to a more efficient exploitation of the axial properties of the SWNTs and of the polymer chain at the interface, in agreement with experimental results. Our findings demonstrate that the mechanical bond imparts distinctive advantageous properties to SWNT derivatives as polymer fillers.Comment: 39 pages, 19 figure

DISSOLVED ORGANIC MATTER MOLECULAR FINGERPRINT OF THE WATER MASSES IN THE CAPE VERT FRONTAL ZONE

Oral communicationOcean water masses have been traditionally characterized by the thermohaline and conservative chemical properties (e.g. preformed nutrients) at their respective source regions. However, water masses also can exhibit characteristic levels of other individual compounds or emerging properties associated to compound classes. In this regard, the objective of this contribution is to characterize the dissolved organic matter (DOM) molecular fingerprint of the water masses present in the Cape Vert Frontal Zone (CVFZ). For this purpose, a set of 133 samples was collected from the surface to 4000 m depth in the CVFZ during the FLUXES I cruise (12 July - 11 August 2017) and isolated by solid-phase extraction (SPE), using styrene divinyl benzene polymer cartridges (PPL). The molecular analysis of these SPE-PPL extracts was performed using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS), a method capable of identifying thousands of molecular formulae in DOM. These analyses have been combined with an optimum multiparameter (OMP) water mass analysis to obtain characteristic molecular indices for the eleven water masses present in the CVFZ, stemming from the subtropical and subpolar North and South Atlantic as well as from the Arctic and Antarctic Oceans. In particular, emerging properties such as the molecular diversity (D), mean molecular mass (MW), mean C:N ratio, aromaticity index (AI), double bond equivalent (DBE), and main molecular groups, as well as different compounds (e.g. Lignin) and individual heteroatoms were quantified.ASL

Suppressors of Cytokine Signaling 3 Expression in Eosinophils: Regulation by PGE2 and Th2 Cytokines

Asthma and nonasthmatic eosinophilic bronchitis (NAEB) are respiratory disorders characterized by a predominance of Th2 cells and eosinophilic inflammation. Suppressors of cytokine signaling (SOCS) proteins play an important role in Th2-mediated allergic responses through control of the balance between Th1 and Th2 cells, particularly, SOCS3 and SOCS5. The aim of this study was to analyze SOCS expression in human peripheral blood eosinophils from patients with asthma, NAEB and healthy controls. SOCS expression in eosinophils from subjects was demonstrated by different techniques. Results showed that expression of SOCS3 in eosinophils and CD4 T cells from patients was higher than in healthy subjects. In addition, we demonstrated that prostaglandin E2 (PGE2) and Th2 cytokines are able to upregulate SOCS3 production in eosinophils and attenuate its degranulation. In conclusion, eosinophils are able to transcribe and translate SOCS3 protein and can contribute to the regulation of the Th1/Th2 balance through SOCS3 production

Dissolved organic nitrogen production and export by meridional overturning in the eastern subpolar North Atlantic

Research articleDissolved organic matter (DOM) is produced in the surface and exported towards the deep ocean, adding ∼ 2 PgC/year to the global carbon export. Due to its central role in the Meridional Overturning Circulation, the eastern subpolar North Atlantic (eSPNA) contributes largely to this export. Here we quantify the transport and budget of dissolved organic nitrogen (DON) in the eSPNA, in a box delimited by the OVIDE 2002 section and the Greenland-Iceland-Scotland sills. The Meridional Overturning Circulation exports >15.9 TgN/year of DON downward and, contrary to the extended view that these are materials of subtropical origin, up to 33% of the vertical flux derives from a net local DON production of 7.1 ± 2.6 TgN/year. The low C:N molar ratio of DOM production (7.4 ± 4.1) and the relatively short transit times in the eSPNA (3 ± 1 year) suggest that local biogeochemical transformations result in the injection of fresh bioavailable DOM to the deep ocean.Versión del editor3,79

Bacterioplankton responses to riverine and atmospheric inputs in a coastal upwelling system (Ría de Vigo, NW Spain)

12 páginas, 5 figuras, 2 tablasAnthropogenic pressures are changing the magnitude and nature of matter inputs into the ocean. The Ría de Vigo (NW Spain) is a highly productive and dynamic coastal system that is likely affected by such alterations. Previous nutrient-addition microcosm experiments conducted during contrasting hydrographic conditions suggested that heterotrophic bacteria are limited by organic carbon (C) and occasionally co-limited by inorganic nutrients in this coastal area. In order to assess short-term responses in biomass, production, and respiration of heterotrophic bacteria from the Ría de Vigo to increasing amounts of natural inputs of matter, we conducted 6 microcosm experiments, wherein surface seawater collected in spring, summer, and autumn was mixed with increasing amounts of dissolved natural matter concentrates from riverine and atmospheric origin. Simultaneous experiments with controlled inorganic and/or organic additions indicated that bacteria were co-limited by inorganic nutrients and C in spring and summer and primarily limited by C in autumn. Production responded more than biomass to increasing inputs of matter, whereas respiration did not change. The bacterial production response to increasing dissolved organic C load associated with riverine and atmospheric inputs was strongly related to the relative phosphorus (P) content of the dissolved matter concentrates. Our data suggest that bacterial production might decrease with the increase of P-deficient allochthonous matter inputs, which would have important biogeochemical consequences for C cycling in coastal areasThis research was supported by the Spanish Ministry of Science and Innovation through project REIMAGE (grants CTM2011-30155-C03-01 and CTM2011-30155-C03-02) and by the Xunta the Galicia trough project DIMENSION (grant EM2013/023). E. B-L was funded by a F.P.I. MICINN fellowship. M.N.-C. was funded by the CSIC Program "Junta para la Ampliación de Estudios" co-financed by the ESF. S.M.G. was funded by a Marie Curie fellowshipPeer reviewe

Bacterioplankton responses to riverine and atmospheric inputs in a coastal upwelling system (Ría de Vigo, NW Spain)

Original research paperAnthropogenic pressures are changing the magnitude and nature of matter inputs into the ocean. The Ría de Vigo (NW Spain) is a highly productive and dynamic coastal system that is likely affected by such alterations. Previous nutrient-addition microcosm experiments conducted during contrasting hydrographic conditions suggested that heterotrophic bacteria are limited by organic carbon (C) and occasionally co-limited by inorganic nutrients in this coastal area. In order to assess short-term responses in biomass, production, and respiration of heterotrophic bacteria from the Ría de Vigo to increasing amounts of natural inputs of matter, we conducted 6 microcosm experiments, wherein surface seawater collected in spring, summer, and autumn was mixed with increasing amounts of dissolved natural matter concentrates from riverine and atmospheric origin. Simultaneous experiments with controlled inorganic and/or organic additions indicated that bacteria were co-limited by inorganic nutrients and C in spring and summer and primarily limited by C in autumn. Production responded more than biomass to increasing inputs of matter, whereas respiration did not change. The bacterial production response to increasing dissolved organic C load associated with riverine and atmospheric inputs was strongly related to the relative phosphorus (P) content of the dissolved matter concentrates. Our data suggest that bacterial production might decrease with the increase of P-deficient allochthonous matter inputs, which would have important biogeochemical consequences for C cycling in coastal areas.Spanish Ministry of Science and Innovation, MINECO, CSIC, Xunta of Galicia and European Union (Marie Curie Grants)Versión del edito

Biogeochemistry of dissolved and suspended organic matter in the Cape Vert Frontal Zone (NW Africa)

Oral communicationThe Cape Verde Frontal Zone (CVFZ) in the southern boundary of the Canary Current Upwelling Ecosystem, is a highly dynamic area, featuring large vertical and horizontal export fluxes of organic matter (OM) due to the interaction of the Cape Verde Front (CVF) with the Mauritanian upwelling. To study the interplay between transport and biogeochemical processes driving the distribution of OM in the CVFZ, full-depth profiles of dissolved (DOM) and suspended particulate (POM) OM were obtained during the FLUXES I cruise in August 2017. Distributions of surface DOM and POM and their stoichiometry were influenced by the mesoscale variability at the frontal region, showing significant differences north and south of the CVF and between stations close and distant to the Mauritanian coast. The C&colon;N molar ratio of DOM and POM showed average vertical gradients, increasing from 12.1 and 8.0 in surface to 15.6 and 17.0 respectively in deeps waters, deviating from the traditional Redfield ratio. In the meso- and bathypelagic zones, meridional and cross-shore gradients were detected within samples belonging to the same water mass, indicating that their properties were re-shaped by biogeochemical processes within the CVFZ. Correlations between apparent oxygen utilization and OM indicate that DOM&plus;POM contributed only to 8.1&percnt; of the carbon and 17.8&percnt; of the nitrogen mineralisation in the water column, suggesting that the local carbon demand is mainly supported by sinking POM and N containing compounds are mineralised to a larger extend than C containing compoundsASL

Variability of moisture sources in the Mediterranean region during the period 1980-2000

In this study, seasonal and interannual variability of the main atmospheric moisture sources over eight regions in the Mediterranean basin were investigated along a 21 year period. The Lagrangian dispersion model FLEXPART, developed by Stohl and James [2004, 2005], was applied to identify the contribution of humidity to the moisture budget of each region. This methodology is used to compute budgets of evaporation minus precipitation (E-P) by calculating changes in the specific humidity along backward trajectories, for the preceding 10 day periods. The results show clear seasonal differences in the moisture sources between wet and dry seasons. The Western Mediterranean Sea is the dominant moisture source for almost all the regions in the Mediterranean basin during the wet season, while the local net evaporation dominates during the dry season. The highest interannual variability is found in contributions to the Iberian Peninsula, Italy, and the Eastern Mediterranean. It is seen that the role of teleconnections is more limited than for the precipitation recorded in the region

Serum micrornas as tool to predict early response to benralizumab in severe eosinophilic asthma

Severe eosinophilic asthma poses a serious health and economic problem, so new therapy approaches have been developed to control it, including biological drugs such as benralizumab, which is a monoclonal antibody that binds to IL-5 receptor alpha subunit and depletes peripheral blood eosinophils rapidly. Biomarkers that predict the response to this drug are needed so that microRNAs (miRNAs) can be useful tools. This study was performed with fifteen severe eosinophilic asthmatic patients treated with benralizumab, and serum miRNAs were evaluated before and after treatment by semi-quantitative PCR (qPCR). Patients showed a clinical improvement after benralizumab administration. Additionally, deregulation of miR-1246, miR-5100 and miR-338-3p was observed in severe asthmatic patients after eight weeks of therapy, and a correlation was found between miR-1246 and eosinophil counts, including a number of exacerbations per year in these severe asthmatics. In silico pathway analysis revealed that these three miRNAs are regulators of the MAPK signaling pathway, regulating target genes implicated in asthma such as NFKB2, NFATC3, DUSP1, DUSP2, DUSP5 and DUSP16. In this study, we observed an altered expression of miR-1246, miR-5100 and miR-338-3p after eight weeks of benralizumab administration, which could be used as early response markers.This manuscript was funded by Fondo de Investigación Sanitaria–FIS and FEDER (Fondo Europeo de Desarrollo Regional) [PI15/00803, PI18/00044, and FI16/00036], CIBER de Enfermedades Respiratorias (CIBERES), Merck Health Foundation funds, and Ministerio de Ciencia, Innovación y Universidades (RTC-2017-6501-1