Light rare earth element depletion during Deepwater Horizon blowout methanotrophy.

Rare earth elements have generally not been thought to have a biological role. However, recent work has demonstrated that the light REEs (LREEs: La, Ce, Pr, and Nd) are essential for at least some methanotrophs, being co-factors in the XoxF type of methanol dehydrogenase (MDH). We show here that dissolved LREEs were significantly removed in a submerged plume of methane-rich water during the Deepwater Horizon (DWH) well blowout. Furthermore, incubation experiments conducted with naturally methane-enriched waters from hydrocarbon seeps in the vicinity of the DWH wellhead also showed LREE removal concurrent with methane consumption. Metagenomic sequencing of incubation samples revealed that LREE-containing MDHs were present. Our field and laboratory observations provide further insight into the biochemical pathways of methanotrophy during the DWH blowout. Additionally, our results are the first observations of direct biological alteration of REE distributions in oceanic systems. In view of the ubiquity of LREE-containing MDHs in oceanic systems, our results suggest that biological uptake of LREEs is an overlooked aspect of the oceanic geochemistry of this group of elements previously thought to be biologically inactive and an unresolved factor in the flux of methane, a potent greenhouse gas, from the ocean.

Trace element and isotope deposition across the air-sea interface: progress and research needs.

The importance of the atmospheric deposition of biologically essential trace elements, especially iron, is widely recognized, as are the difficulties of accurately quantifying the rates of trace element wet and dry deposition and their fractional solubility. This paper summarizes some of the recent progress in this field, particularly that driven by the GEOTRACES, and other, international research programmes. The utility and limitations of models used to estimate atmospheric deposition flux, for example, from the surface ocean distribution of tracers such as dissolved aluminium, are discussed and a relatively new technique for quantifying atmospheric deposition using the short-lived radionuclide beryllium-7 is highlighted. It is proposed that this field will advance more rapidly by using a multi-tracer approach, and that aerosol deposition models should be ground-truthed against observed aerosol concentration data. It is also important to improve our understanding of the mechanisms and rates that control the fractional solubility of these tracers. Aerosol provenance and chemistry (humidity, acidity and organic ligand characteristics) play important roles in governing tracer solubility. Many of these factors are likely to be influenced by changes in atmospheric composition in the future. Intercalibration exercises for aerosol chemistry and fractional solubility are an essential component of the GEOTRACES programme.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

Treatment with amantadine potentiated motor learning in a patient with traumatic brain injury of 15 years' duration.

This study sought to determine whether pharmacotherapy with amantadine potentiates motor recovery in an 18-year-old man with traumatic brain injury (TBI) of 15 years' duration. This uncontrolled single-case multiple-baseline design allowed preliminary evaluation of amantadine within the context of standard data-collection procedures on the TBI unit. Measurements tracked speed of wheelchair propulsion, wheelchair transfer, donning shirt, and inserting pegs into holes. Data were collected during a 3-week practice period, followed by a 6-week period of practice plus daily treatment with amantadine. The rate at which performance improved was significantly increased with drug treatment in the wheelchair transfer task. There was a statistically insignificant trend toward improvement in donning shirt. Amantadine did not appear to potentiate recovery in the wheelchair propulsion or peg placement tasks. The results suggest that amantadine facilitates some measures of motor recovery in chronic brain injury. Further trials are warranted to investigate this issue.

The relationship between hostility and beta-adrenergic receptor physiology in health young males.

OBJECTIVE: We examined the relationship between hostility and mononuclear leukocyte (MNL) beta-adrenergic receptor function in a sample of young healthy males. METHOD: Thirty subjects were selected for having scored above 20 (N = 11) and below 14 (N = 19) on the Cook-Medley Hostility (Ho) scale. MNL beta-adrenergic receptor function was characterized in terms of receptor density (Bmax) and ligand-binding affinity (Kd) in homogenized cells, and intracellular cyclic adenosine monophosphate (cAMP) responses to saline, isoproterenol, and forskolin in whole cells. Subjects also completed the Multidimensional Anger Inventory (MAI), which assesses dimensions of anger. RESULTS: Relative to men with low Ho scores, men with Ho scores above 20 showed lower receptor number and greater forskolin-stimulated cAMP. Moreover, high hostile men reported a greater frequency of anger, longer duration of anger, more frequent brooding, and a hostile outlook. CONCLUSIONS: These data indicate that adrenergic receptor down-regulation is associated with hostility. This association may be linked to hostile persons' propensity for excessive and prolonged neuroendocrine responses to either psychological stressors or the experience of chronic stress associated with frequent and prolonged bouts of anger.