Dissolved gases in the deep North Atlantic track ocean ventilation processes.

Gas exchange between the atmosphere and ocean interior profoundly impacts global climate and biogeochemistry. However, our understanding of the relevant physical processes remains limited by a scarcity of direct observations. Dissolved noble gases in the deep ocean are powerful tracers of physical air-sea interaction due to their chemical and biological inertness, yet their isotope ratios have remained underexplored.

Influence of sample volume on nitrate N and O isotope ratio analyses with the denitrifier method.

Rationale: Analyses of the isotope ratios of nitrogen ( N/ N) and oxygen ( O/ O) in nitrate (NO ) with the denitrifier method require relatively high sample volumes at low concentrations (≤1 μM) to afford sufficient analyte for mass spectrometry, resulting in isotopic offsets compared to more concentrated samples of the same isotopic composition.

Methods: To uncover the origins of isotopic offsets, we analyzed the N and O isotope ratios of NO reference materials spanning concentrations of 0.5-20 μM.

Global reconstruction reduces the uncertainty of oceanic nitrous oxide emissions and reveals a vigorous seasonal cycle.

Assessment of the global budget of the greenhouse gas nitrous oxide ([Formula: see text]O) is limited by poor knowledge of the oceanic [Formula: see text]O flux to the atmosphere, of which the magnitude, spatial distribution, and temporal variability remain highly uncertain. Here, we reconstruct climatological [Formula: see text]O emissions from the ocean by training a supervised learning algorithm with over 158,000 [Formula: see text]O measurements from the surface ocean-the largest synthesis to date. The reconstruction captures observed latitudinal gradients and coastal hot spots of [Formula: see text]O flux and reveals a vigorous global seasonal cycle.

Microbial ecosystem dynamics drive fluctuating nitrogen loss in marine anoxic zones.

The dynamics of nitrogen (N) loss in the ocean's oxygen-deficient zones (ODZs) are thought to be driven by climate impacts on ocean circulation and biological productivity. Here we analyze a data-constrained model of the microbial ecosystem in an ODZ and find that species interactions drive fluctuations in local- and regional-scale rates of N loss, even in the absence of climate variability. By consuming O to nanomolar levels, aerobic nitrifying microbes cede their competitive advantage for scarce forms of N to anaerobic denitrifying bacteria.

Utilization of urea and cyanate in waters overlying and within the eastern tropical north Pacific oxygen deficient zone.

In marine oxygen deficient zones (ODZs), which contribute up to half of marine N loss, microbes use nitrogen (N) for assimilatory and dissimilatory processes. Here, we examine N utilization above and within the ODZ of the Eastern Tropical North Pacific Ocean, focusing on distribution, uptake and genes for the utilization of two simple organic N compounds, urea and cyanate. Ammonium, urea and cyanate concentrations generally peaked in the oxycline while uptake rates were highest in the surface.

Biological nitrogen fixation in the oxygen-minimum region of the eastern tropical North Pacific ocean.

Biological nitrogen fixation (BNF) was investigated above and within the oxygen-depleted waters of the oxygen-minimum zone of the Eastern Tropical North Pacific Ocean. BNF rates were estimated using an isotope tracer method that overcame the uncertainty of the conventional bubble method by directly measuring the tracer enrichment during the incubations. Highest rates of BNF (~4 nM day) occurred in coastal surface waters and lowest detectable rates (~0.

Cultivation of a chemoautotroph from the SUP05 clade of marine bacteria that produces nitrite and consumes ammonium.

Marine oxygen minimum zones (OMZs) are expanding regions of intense nitrogen cycling. Up to half of the nitrogen available for marine organisms is removed from the ocean in these regions. Metagenomic studies have identified an abundant group of sulfur-oxidizing bacteria (SUP05) with the genetic potential for nitrogen cycling and loss in OMZs.

Biomarker discovery and transcriptomic responses in Daphnia magna exposed to munitions constituents.

Ecotoxicogenomic approaches are emerging as alternative methods in environmental monitoring because they allow insight into pollutant modes of action and help assess the causal agents and potential toxicity beyond the traditional end points of death, growth, and reproduction. Gene expression analysis has shown particular promise for identifying gene expression biomarkers of chemical exposure that can be further used to monitor specific chemical exposures in the environment. We focused on the development of gene expression markers to detect and discriminate between chemical exposures.

Immunostimulatory oligonucleotides block allergic airway inflammation by inhibiting Th2 cell activation and IgE-mediated cytokine induction.

A single treatment with a CpG-containing immunostimulatory DNA sequence (ISS) given before allergen challenge can inhibit T helper type 2 cell (Th2)-mediated airway responses in animal models of allergic asthma; however, the mechanism of this inhibition remains largely undefined. Here, we demonstrate that airway delivery of ISS before allergen challenge in Th2-primed mice acts in two distinct ways to prevent the allergic responses to this challenge. The first is to prevent induction of cytokines from allergen-specific Th2 cells, as demonstrated by the nearly complete inhibition of Th2 cytokine production, Th2-dependent functional responses, and gene induction patterns.

Nucleic acids of mammalian origin can act as endogenous ligands for Toll-like receptors and may promote systemic lupus erythematosus.

Raised serum levels of interferon (IFN)-alpha have been observed in systemic lupus erythematosus (SLE) patients, and these levels are correlated with both disease activity and severity. The origin of this IFN-alpha is still unclear, but increasing evidence suggests the critical involvement of activated plasmacytoid predendritic cells (PDCs). In SLE patients, DNA and RNA viruses, as well as immune complexes (ICs), that consist of autoantibodies specific to self-DNA and RNA protein particles can stimulate production of IFN-alpha.

Inhibitors of TLR-9 act on multiple cell subsets in mouse and man in vitro and prevent death in vivo from systemic inflammation.

In parallel with the discovery of the immunostimulatory activities of CpG-containing oligodeoxynucleotides, several groups have reported specific DNA sequences that could inhibit activation by CpG-containing oligodeoxynucleotides in mouse models. We show that these inhibitory sequences, termed IRS, inhibit TLR-9-mediated activation in human as well as mouse cells. This inhibitory activity includes proliferation and IL-6 production by B cells, and IFN-alpha and IL-12 production by plasmacytoid dendritic cells.