10 research outputs found

    Covariation in Plant Functional Traits and Soil Fertility within Two Species-Rich Forests

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    The distribution of plant species along environmental gradients is expected to be predictable based on organismal function. Plant functional trait research has shown that trait values generally vary predictably along broad-scale climatic and soil gradients. This work has also demonstrated that at any one point along these gradients there is a large amount of interspecific trait variation. The present research proposes that this variation may be explained by the local-scale sorting of traits along soil fertility and acidity axes. Specifically, we predicted that trait values associated with high resource acquisition and growth rates would be found on soils that are more fertile and less acidic. We tested the expected relationships at the species-level and quadrat-level (20×20 m) using two large forest plots in Panama and China that contain over 450 species combined. Predicted relationships between leaf area and wood density and soil fertility were supported in some instances, but the majority of the predicted relationships were rejected. Alternative resource axes, such as light gradients, therefore likely play a larger role in determining the interspecific variability in plant functional traits in the two forests studied

    A Glial Variant of the Vesicular Monoamine Transporter Is Required To Store Histamine in the Drosophila Visual System

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    Unlike other monoamine neurotransmitters, the mechanism by which the brain's histamine content is regulated remains unclear. In mammals, vesicular monoamine transporters (VMATs) are expressed exclusively in neurons and mediate the storage of histamine and other monoamines. We have studied the visual system of Drosophila melanogaster in which histamine is the primary neurotransmitter released from photoreceptor cells. We report here that a novel mRNA splice variant of Drosophila VMAT (DVMAT-B) is expressed not in neurons but rather in a small subset of glia in the lamina of the fly's optic lobe. Histamine contents are reduced by mutation of dVMAT, but can be partially restored by specifically expressing DVMAT-B in glia. Our results suggest a novel role for a monoamine transporter in glia that may be relevant to histamine homeostasis in other systems

    Deep Underground Neutrino Experiment (DUNE), far detector technical design report, volume III: DUNE far detector technical coordination

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    The preponderance of matter over antimatter in the early universe, the dynamics of the supernovae that produced the heavy elements necessary for life, and whether protons eventually decay—these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our universe, its current state, and its eventual fate. The Deep Underground Neutrino Experiment (DUNE) is an international world-class experiment dedicated to addressing these questions as it searches for leptonic charge-parity symmetry violation, stands ready to capture supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector technical design report (TDR) describes the DUNE physics program and the technical designs of the single- and dual-phase DUNE liquid argon TPC far detector modules. Volume III of this TDR describes how the activities required to design, construct, fabricate, install, and commission the DUNE far detector modules are organized and managed. This volume details the organizational structures that will carry out and/or oversee the planned far detector activities safely, successfully, on time, and on budget. It presents overviews of the facilities, supporting infrastructure, and detectors for context, and it outlines the project-related functions and methodologies used by the DUNE technical coordination organization, focusing on the areas of integration engineering, technical reviews, quality assurance and control, and safety oversight. Because of its more advanced stage of development, functional examples presented in this volume focus primarily on the single-phase (SP) detector module

    Floral diversity during Plio-Pleistocene Siwalik sedimentation (Kimin Formation) in Arunachal Pradesh, India, and its palaeoclimatic significance

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    A morpho-taxonomic study of leaf remains from the upper part of the Siwalik succession of sediments (Kimin Formation; upper Pliocene to lower Pleistocene) of Papumpare district, Arunachal Pradesh, India, revealed 23 species representing 20 genera belonging to 15 angiosperm families. The recovered fossil leaves are comparable to modern Bambusa tulda Roxb. (Poaceae), Mangifera indica Linn., Dracontomelum mangiferum Blume (Anacardiaceae); Chonemorpha macrophylla G. Don (Apocynaceae); Pongamia pinnata (L) Pierre., Millettia pachycarpa Benth., Dalbergia rimosa Roxb., Millettia extensa (Fabaceae); Macaranga denticulate Muell. Arg., Croton caudatus Geisel. (Euphorbiaceae); Combretum decandrum Roxb. (Combretaceae); Dysoxylum procerum Hiern. (Meliaceae); Dipterocarpus sp. Gaertn.f. (Dipterocarpaceae); Actinodaphne angustifolia Nees., Actinodaphne obovata Blume., Lindera pulcherrima Benth., Litsea salicifolia Roxb. (Lauraceae); Calophyllum polyanthum Wall. (Clusiaceae); Knema glaucescens Hook.f. (Myristaceae); Canarium bengalense Roxb. (Burseraceae); Quercus lamellose Smith; Quercus semicarpifolia Smith (Fagaceae); and Berchemia floribunda Wall. (Rhamnaceae). Among these taxa, 11 species are recorded as new to the Neogene flora of India. Analysis of the floral assemblage with respect to the distribution pattern of modern equivalent taxa and the physiognomic characters of the fossil leaves, suggests that a tropical evergreen forest was growing in a warm humid climate in the region at the time of deposition. This is in contrast to modern tropical semi-evergreen forests that occupy the area. Values of mean annual temperature (MAT) of 29.3°C and mean annual precipitation (MAP) of 290 mm have been calculated using leaf-margin characters and fossil leaf size

    Climatic reconstruction of two Pliocene floras from Mexico

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    The role that climate plays in influencing the physiognomy of modern and fossil plant communities is widely acknowledged and forms the basis for several palaeoclimate proxies. In this work, both univariate Leaf Margin Analysis and multivariate Climate/Leaf Analysis Multivariate Program (CLAMP) were used for the climatic reconstruction of two fossil localities of the Atotonilco El Grande Formation. Using the predominantly North American and Asian calibration data set PHYSG3BRC, supplemented with new African material, results from two sites, Los Baños (present position 20°18′18″N, 98°42′44.4″W) and Sanctorum (20°18′18.5″N and 98°46′52.2″W), indicate that during the Pliocene a mesothermal climate existed with mean annual temperatures between 12 and 22°C, with the most likely being approximately 15°C, and a mean annual temperature range of 21°C. A distinct seasonal variation in rainfall is evident with a mean annual relative humidity of 60–70%. Differences between the sites can be explained by differences in depositional regime and spatial heterogeneity in the predominantly Quercus-dominated woodland. The continuous subsequent uplift of the Sierra Madre Oriental, the resulting development of a rain shadow, and the eventual disappearance of a palaeolake appear to have caused a transition to the modern xerophytic shrub vegetation
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