Carbonyl sulfide (COS) is an atmospheric trace gas of interest for C cycle research because COS uptake by continental vegetation is strongly related to terrestrial gross primary productivity (GPP), the largest and most uncertain flux in atmospheric CO2 budgets. However, to use atmospheric COS as an additional tracer of GPP, an accurate quantification of COS exchange by soils is also needed. At present, the atmospheric COS budget is unbalanced globally, with total COS flux estimates from oxic and anoxic soils that vary between -409 and -89 GgS yr(-1). This uncertainty hampers the use of atmospheric COS concentrations to constrain GPP estimates through atmospheric transport inversions. In this study we implemented a mechanistic soil COS model in the ORCHIDEE (Organising Carbon and Hydrology In Dynamic Ecosystems) land surface model to simulate COS fluxes in oxic and anoxic soils. Evaluation of the model against flux measurements at seven sites yields a mean root mean square deviation of 1.6 pmolm(-2)s(-1), instead of 2 pmol m(-2)s(-1) when using a previous empirical approach that links soil COS uptake to soil heterotrophic respiration. However, soil COS model evaluation is still limited by the scarcity of observation sites and long-term measurement periods, with all sites located in a latitudinal band between 39 and 62 degrees N and no observations during wintertime in this study. The new model predicts that, globally and over the 2009-2016 period, oxic soils act as a net uptake of -126 GgS yr(-1) and anoxic soils are a source of +96 GgS yr(-1), leading to a global net soil sink of only -30 GgS yr(-1), i.e. much smaller than previous estimates. The small magnitude of the soil fluxes suggests that the error in the COS budget is dominated by the much larger fluxes from plants, oceans, and industrial activities. The predicted spatial distribution of soil COS fluxes, with large emissions from oxic (up to 68.2 pmol COS m(-2) s(-1)) and anoxic (up to 36.8 pmol COS m(-2) S-1) soils in the tropics, especially in India and in the Sahel region, marginally improves the latitudinal gradient of atmospheric COS concentrations, after transport by the LMDZ (Laboratoire de Meteorologie Dynamique) atmospheric transport model. The impact of different soil COS flux representations on the latitudinal gradient of the atmospheric COS concentrations is strongest in the Northern Hemisphere. We also implemented spatiotemporal variations in near-ground atmospheric COS concentrations in the modelling of biospheric COS fluxes, which helped reduce the imbalance of the atmospheric COS budget by lowering soil COS uptake by 10 % and plant COS uptake by 8 % globally (with a revised mean vegetation budget of -576 GgS yr(-1) over 2009-2016). Sensitivity analyses highlighted the different parameters to which each soil COS flux model is the most responsive, selected in a parameter optimization framework. Having both vegetation and soil COS fluxes modelled within ORCHIDEE opens the way for using observed ecosystem COS fluxes and larger-scale atmospheric COS mixing ratios to improve the simulated GPP, through data assimilation techniques.

Measurements of carbonyl sulfide (OCS) enable independent estimates of regional stomatal conductance provided that non-stomatal OCS fluxes are well constrained. OCS is taken up through plant leaves, following the same pathway as CO2; in contrast to CO2, OCS is irreversibly destroyed in plant leaves and plants do not typically exhibit OCS emissions. Ecosystem uptake of OCS can indicate changes in stomatal opening. Here we present an empirical model to assess the potential impact of soil OCS exchange, the non-Stomatal OCS exchange Empirical Model (SOCSEM, version 0). We created biome-specific response curves characterizing soil OCS exchange and restricted the model design to require only knowledge of soil moisture and surface temperature because remote sensing observations are available for these two features. Comparing the model to field-based chamber observations reveal deviations that can be attributed to missing complexity of the ground surface (having excluded litter and plants without regulated stomata), shortwave radiation, or the soil environment. For agricultural regions with known net emissions, we use remotely-sensed surface temperature data and demonstrate that data resolution can affect anticipated fluxes. We further investigate the influence of regions with unknown soil OCS responses, for example, Arctic tundra. We compare our model to a process-based and respiration-based soil OCS exchange model that has been implemented in a land surface model. Further field study of tropical and arctic ecosystems in conjunction with studies of non-stomatal surfaces in addition to soil (e.g., bryophytes) will increase confidence in applying OCS as a regional tracer for stomatal conductance.

Elevations from the Mars Orbiter Laser Altimeter (MOLA) have been used to construct a precise topographic map of the martian north polar region. The northern ice cap has a maximum elevation of 3 kilometers above its surroundings but Lies within a 5-kilometer-deep hemispheric depression that is contiguous with the area into which most outflow channels emptied, Polar cap topography displays evidence of modification by ablation, flow, and wind and is consistent with a primarily H2O composition. Correlation of topography with images suggests that the cap was more spatially extensive in the past. The cap volume of 1.2 x 10(6) to 1.7 x 10(6) cubic kilometers is about half that of the Greenland ice cap. Clouds observed over the polar cap are Likely composed of CO2 that condensed out of the atmosphere during northern hemisphere winter. Many clouds exhibit dynamical structure Likely caused by the interaction of propagating wave fronts with surface topography.

Serotonin (5-hydroxytryptamine; 5-HT) synthesis and release are thought to be high during the day and low at night in the pineal. We identify a sharp rise in 5-HT synthesis and release soon after the lights are off during the dark phase of the circadian cycle, which precedes the nocturnal rise in melatonin synthesis and secretion. This tri-phasic 5-HT release, which consists of constant levels during the day, elevated levels at early night, a low level at late night, persists in the constant darkness, and is influenced strongly by light at night. The early nocturnal peak of 5-HT secretion is controlled directly by the sympathetic innervation originating from the superior cervical ganglion. We find that the marked decrease of 5-HT contents and release later at night is solely due to the consumption by melatonin synthesis and that the early nocturnal increase of 5-HT synthesis and release is independent of the melatonin synthesis. In the absence of melatonin synthesis, the tri-phasic 5-HT release becomes bi-phasic, with the nighttime level twice as high as that of the day value. We further demonstrate that the early night increase in 5-HT synthesis is controlled by beta-adrenergic receptor, and that the increased 5-HT release is mediated by alpha-adrenergic signaling. These observations suggest that 5-HT synthesis and secretion in the pineal is diurnally regulated independently of melatonin formation by adrenergic innervation, which may serve as a unique model system for investigating the regulation of 5-HT synthesis and release.

The Mars Orbiter Laser Altimeter (MOLA), an instrument on the Mars Global Surveyor spacecraft, has measured the topography, surface roughness, and 1.064-mum reflectivity of Mars and the heights of volatile and dust clouds. This paper discusses the function of the MOLA instrument and the acquisition, processing, and correction of observations to produce global data sets. The altimeter measurements have been converted to both gridded and spherical harmonic models for the topography and shape of Mars that have vertical and radial accuracies of similar to1 m with respect to the planet's center of mass. The current global topographic grid has a resolution of 1/64 degrees in latitude x 1/32 degrees in longitude (I x 2 km(2) at the equator). Reconstruction of the locations of incident laser pulses on the Martian surface appears to be at the 100-m spatial accuracy level and results in 2 orders of magnitude improvement in the global geodetic grid of Mars. Global maps of optical pulse width indicative of 100-m-scale surface roughness and 1.064-mum reflectivity with an accuracy of 5% have also been obtained.

Using on-line microdialysis, we have characterized in vivo dynamics of pineal 5-hydroxytryptamine (5-HT; serotonin) release. Daily pineal 5-HT output is triphasic: (i) 5-HT levels are constant and high during the day; (if) early in the night, there is a novel sharp rise in 5-HT synthesis and release, which precedes the nocturnal rise in melatonin synthesis; and (iii) late in the night, levels are low. This triphasic 5-HT production persists in constant darkness and is influenced strongly by intrusion of light at night. We demonstrate that both diurnal 5-HT synthesis and 5-HT release are activated by sympathetic innervation from the superior cervical ganglion and show that these processes are controlled by distinct receptors. The increase in 5-HT synthesis is controlled by beta-adrenergic receptors, whereas the increase in 5-HT release is mediated by a-adrenergic signaling. On the other hand, the marked decrease in 5-HT content and release late at night is a passive process, influenced by the extent of melatonin synthesis. In the absence of melatonin synthesis, the late-night decline in 5-HT release is prevented, reaching levels roughly twice as high as that of the day value. In summary, our results demonstrate that 5-HT levels display marked circadian rhythms that depend on adrenergic signaling.

The 3-O-sulfotransferases (3OSTs) catalyze the addition of sulfate groups at the 3-OH site of glucosamine in heparan sulfate proteoglycans, which serve as critical mediators of various biological functions. We demonstrate that the 3OST2 isoform is expressed at high levels in the rat pineal specifically during the daylight hours. The dramatic diurnal rhythm of 3OST2 is regulated by central clock-controlled activities of the superior cervical ganglion, persists in constant darkness, and is inducible by light at nighttime. Importantly, 3OST2 transcription is blocked by beta-adrenergic agonists that activate the pineal melatonin formation and is induced by beta-adrenergic antagonists, which block melatonin production in vivo. Because of the inverse expression and regulation patterns of 3OST2 with serotortin N-acetyltransferase, the enzyme controlling the melatonin rhythm in the pineal, we tested the effects of forced expression of 3OST2 in the night pineals on N-acetyltransferase gene expression and melatonin production and found that, surprisingly, 3OST2 expression at night fails to interfere with melatonin synthesis. These data suggest 3OST2 may serve a unique function in the pineal that may be independent of melatonin formation.

This study describes the development of a new technique for long-term measurement of daily 5-hydroxytryptamine (5-HT) and melatonin contents in the pineal gland of freely moving rats. The technique features a number of novel improvements over previous protocols. It allows visualization of the pineal gland for accurate targeting of the guide cannula, which minimizes bleeding; incurs no direct injury to the surrounding brain tissues; and causes no interference with the sympathetic innervation from the superior cervical ganglia. Robust releases of melatonin and indole precursors were continuously monitored quantitatively and reproducibly for more than 2 wk in the same animal. In addition, effects of pharmacological agents on in vivo pineal circadian rhythms can be studied reproducibly over time, and gene expression profiles can be correlated with physiological consequences in single animals. Using these approaches, it is found that beta -adrenergic activation leads to decreased release of 5-HT, and that increased cAMP signaling in vivo results in activation of N-acetyltransferase gene induction and melatonin production. These studies will enhance the understanding of signaling pathways that regulate pineal 5-HT and melatonin synthesis and secretion.