Sulfur and methane oxidation by a single microorganism.

Natural and anthropogenic wetlands are major sources of the atmospheric greenhouse gas methane. Methane emissions from wetlands are mitigated by methanotrophic bacteria at the oxic-anoxic interface, a zone of intense redox cycling of carbon, sulfur, and nitrogen compounds. Here, we report on the isolation of an aerobic methanotrophic bacterium, '' strain HY1, which possesses metabolic capabilities never before found in any methanotroph.

Ammonia-oxidizing archaea possess a wide range of cellular ammonia affinities.

Nitrification, the oxidation of ammonia to nitrate, is an essential process in the biogeochemical nitrogen cycle. The first step of nitrification, ammonia oxidation, is performed by three, often co-occurring guilds of chemolithoautotrophs: ammonia-oxidizing bacteria (AOB), archaea (AOA), and complete ammonia oxidizers (comammox). Substrate kinetics are considered to be a major niche-differentiating factor between these guilds, but few AOA strains have been kinetically characterized.

Low yield and abiotic origin of NO formed by the complete nitrifier Nitrospira inopinata.

Nitrous oxide (NO) and nitric oxide (NO) are atmospheric trace gases that contribute to climate change and affect stratospheric and ground-level ozone concentrations. Ammonia oxidizing bacteria (AOB) and archaea (AOA) are key players in the nitrogen cycle and major producers of NO and NO globally. However, nothing is known about NO and NO production by the recently discovered and widely distributed complete ammonia oxidizers (comammox).

Complete Genome Sequence of Methylomonas denitrificans Strain FJG1, an Obligate Aerobic Methanotroph That Can Couple Methane Oxidation with Denitrification.

strain FJG1 is a member of the gammaproteobacterial methanotrophs. The sequenced genome of FJG1 reveals the presence of genes that encode methane, methanol, formaldehyde, and formate oxidation. It also contains genes that encode enzymes for nitrate reduction to nitrous oxide, consistent with the ability of FJG1 to couple denitrification with methane oxidation.

Comparison of Nitrogen Oxide Metabolism among Diverse Ammonia-Oxidizing Bacteria.

Ammonia-oxidizing bacteria (AOB) have well characterized genes that encode and express nitrite reductases (NIR) and nitric oxide reductases (NOR). However, the connection between presence or absence of these and other genes for nitrogen transformations with the physiological production of nitric oxide (NO) and nitrous oxide (N2O) has not been tested across AOB isolated from various trophic states, with diverse phylogeny, and with closed genomes. It is therefore unclear if genomic content for nitrogen oxide metabolism is predictive of net N2O production.

Complete Genome Sequence of Nitrosomonas ureae Strain Nm10, an Oligotrophic Group 6a Nitrosomonad.

The complete genome of Nitrosomonas ureae strain Nm10, a mesophilic betaproteobacterial ammonia oxidizer isolated from Mediterranean soils in Sardinia, Italy, is reported here. This genome represents a cluster 6a nitrosomonad.

Anthrax Toxin Receptor 1 Is Essential for Arteriogenesis in a Mouse Model of Hindlimb Ischemia.

Anthrax toxin receptor 1/tumor endothelial marker 8 (Antxr1 or TEM8) is up-regulated in tumor vasculature and serves as a receptor for anthrax toxin, but its physiologic function is unclear. The objective of this study was to evaluate the role of Antxr1 in arteriogenesis. The role of Antxr1 in arteriogenesis was tested by measuring gene expression and immunohistochemistry in a mouse model of hindlimb ischemia using wild-type and ANTXR1(-/-) mice.

Genome Sequence of Nitrosomonas communis Strain Nm2, a Mesophilic Ammonia-Oxidizing Bacterium Isolated from Mediterranean Soil.

The complete genome sequence of Nitrosomonas communis strain Nm2, a mesophilic betaproteobacterial ammonia oxidizer isolated from Mediterranean soils in Corfu, Greece, is reported here. This is the first genome to describe a cluster 8 Nitrosomonas species and represents an ammonia-oxidizing bacterium commonly found in terrestrial ecosystems.

Diverse electron sources support denitrification under hypoxia in the obligate methanotroph Methylomicrobium album strain BG8.

Aerobic methane-oxidizing bacteria (MOB) are a diverse group of microorganisms that are ubiquitous in natural environments. Along with anaerobic MOB and archaea, aerobic methanotrophs are critical for attenuating emission of methane to the atmosphere. Clearly, nitrogen availability in the form of ammonium and nitrite have strong effects on methanotrophic activity and their natural community structures.

Draft genomes of gammaproteobacterial methanotrophs isolated from terrestrial ecosystems.

Genome sequences of Methylobacter luteus, Methylobacter whittenburyi, Methylosarcina fibrata, Methylomicrobium agile, and Methylovulum miyakonense were generated. The strains represent aerobic methanotrophs typically isolated from various terrestrial ecosystems.

Methane oxidation coupled to nitrate reduction under hypoxia by the Gammaproteobacterium Methylomonas denitrificans, sp. nov. type strain FJG1.

Obligate methanotrophs belonging to the Phyla Proteobacteria and Verrucomicrobia require oxygen for respiration and methane oxidation; nevertheless, aerobic methanotrophs are abundant and active in low oxygen environments. While genomes of some aerobic methanotrophs encode putative nitrogen oxide reductases, it is not understood whether these metabolic modules are used for NOx detoxification, denitrification or other purposes. Here we demonstrate using microsensor measurements that a gammaproteobacterial methanotroph Methylomonas denitrificans sp.

Genome Sequence of the Obligate Gammaproteobacterial Methanotroph Methylomicrobium album Strain BG8.

The complete genome sequence of Methylomicrobium album strain BG8, a methane-oxidizing gammaproteobacterium isolated from freshwater, is reported. Aside from a conserved inventory of genes for growth on single-carbon compounds, M. album BG8 carries a range of gene inventories for additional carbon and nitrogen transformations but no genes for growth on multicarbon substrates or for N fixation.

Complete genome sequence of the aerobic marine methanotroph Methylomonas methanica MC09.

Methylomonas methanica MC09 is a mesophilic, halotolerant, aerobic, methanotrophic member of the Gammaproteobacteria, isolated from coastal seawater. Here we present the complete genome sequence of this strain, the first available from an aerobic marine methanotroph.

Genome sequence of the methanotrophic alphaproteobacterium Methylocystis sp. strain Rockwell (ATCC 49242).

Methylocystis sp. strain Rockwell (ATCC 49242) is an aerobic methane-oxidizing alphaproteobacterium isolated from an aquifer in southern California. Unlike most methanotrophs in the Methylocystaceae family, this strain has a single pmo operon encoding particulate methane monooxygenase but no evidence of the genes encoding soluble methane monooxygenase.

Cholinergic modulation of nucleus accumbens medium spiny neurons.

The rat nucleus accumbens contains acetylcholine-releasing interneurons, presumed to play a regulatory role in the electrical activity of medium spiny output neurons. In order to examine this issue in detail, we made electrophysiological recordings in rat nucleus accumbens slices. These experiments showed that gamma-aminobutyric acid-mediated inhibition of the output neurons might be facilitated by activation of nicotinic acetylcholine receptors, in addition to being suppressed via activation of muscarinic acetylcholine receptors.

Dopamine modulates exocytosis independent of Ca(2+) entry in melanotropic cells.

Dopamine is a known inhibitor of pituitary melanotropic cells. It reduces Ca(2+) influx by hyperpolarizing the cell membrane and by modulating high- and low-voltage-activated (HVA and LVA) Ca(2+) channels. As a result, dopamine reduces the hormonal output of the cell.

A glia-derived acetylcholine-binding protein that modulates synaptic transmission.

There is accumulating evidence that glial cells actively modulate neuronal synaptic transmission. We identified a glia-derived soluble acetylcholine-binding protein (AChBP), which is a naturally occurring analogue of the ligand-binding domains of the nicotinic acetylcholine receptors (nAChRs). Like the nAChRs, it assembles into a homopentamer with ligand-binding characteristics that are typical for a nicotinic receptor; unlike the nAChRs, however, it lacks the domains to form a transmembrane ion channel.

Activation of protein kinase C by oxytocin-related conopressin underlies pacemaker current in Lymnaea central neurons.

The vasopressin/oxytocin-related neuropeptide Lys-conopressin activates two pacemaker currents in central neurons of the mollusk Lymnaea stagnalis. A high-voltage-activated current (I-HVA) is activated at potentials greater than -40 mV and resembles pacemaker currents found in many molluscan neurons. A low-voltage-activated current (I-LVA) activates throughout the range of -90 to 0 mV.

Regulation of exocytosis in neuroendocrine cells: spatial organization of channels and vesicles, stimulus-secretion coupling, calcium buffers and modulation.

Neuroendocrine cells display a similar calcium dependence of release as synapses but a strongly different organization of channels and vesicles. Biophysical and biochemical properties of large dense core vesicle release in neuroendocrine cells suggest that vesicles and channels are dissociated by a distance of 100-300 nm. This distinctive organization relates to the sensitivity of the release process to mobile calcium buffers, the resulting relationship between calcium influx and release and the modulatory mechanisms regulating the efficiency of excitation-release coupling.

All classes of calcium channel couple with equal efficiency to exocytosis in rat melanotropes, inducing linear stimulus-secretion coupling.

1. The contribution of low voltage-activated (LVA) T-type Ca2+ channels and four different types of high voltage-activated (HVA) Ca2+ channel to exocytosis, and the relationship between calcium influx and exocytosis during action potentials (APs) were studied in pituitary melanotropes. 2.

Calcium channels and the release of large dense core vesicles from neuroendocrine cells: spatial organization and functional coupling.

The release of large dense core vesicles (LDCV) by neuroendocrine cells displays a very similar calcium dependence as found in synapses, yet, the organization of channels and vesicles is quite different. Various biophysical properties of the release process, notably a large delay (>10 ms) between excitation and release and a high impact of mobile calcium buffers, suggest that, generally, vesicles and channels do not co-localize as in synapses, but are separated by a distance of 100-300 nm. This review focuses on the consequences of this organization for the functional coupling of calcium channels to LDCV-release in neuroendocrine cells.

Progesterone-metabolite prevents protein kinase C-dependent modulation of gamma-aminobutyric acid type A receptors in oxytocin neurons.

Gonadal steroid feedback to oxytocin neurons during pregnancy is in part mediated via the neurosteroid allopregnanolone (3alpha-OH-DHP), acting as allosteric modulator of postsynaptic gamma-aminobutyric acid type A (GABA(A)) receptors. We describe here a form of nongenomic progesterone signaling by showing that 3alpha-OH-DHP not only potentiates GABA(A) receptor-channel activity but also prevents its modulation by protein kinase C (PKC). Application of oxytocin or stimulation of PKC suppressed the postsynaptic GABA responses of oxytocin neurons in the absence, but not in the presence of 3alpha-OH-DHP.

Roles of G-protein beta gamma, arachidonic acid, and phosphorylation inconvergent activation of an S-like potassium conductance by dopamine, Ala-Pro-Gly-Trp-NH2, and Phe-Met-Arg-Phe-NH2.

Dopamine and the neuropeptides Ala-Pro-Gly-Trp-NH2 (APGWamide or APGWa) and Phe-Met-Arg-Phe-NH2 (FMRFamide or FMRFa) all activate an S-like potassium channel in the light green cells of the mollusc Lymnaea stagnalis, neuroendocrine cells that release insulin-related peptides. We studied the signaling pathways underlying the responses, the role of the G-protein betagamma subunit, and the interference by phosphorylation pathways. All responses are blocked by an inhibitor of arachidonic acid (AA) release, 4-bromophenacylbromide, and by inhibitors of lipoxygenases (nordihydroguaiaretic acid and AA-861) but not by indomethacin, a cyclooxygenase inhibitor.