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131.
DAVID S. DOMOZYCH RICHARD WILSON CATHERINE ROGERS DOMOZYCH 《The Journal of eukaryotic microbiology》2009,56(4):314-322
ABSTRACT. Cosmarium reniforme (Zygnematophyceae, Streptophyta) is a green alga that is commonly found in biofilms of wetlands of the Adirondack region, NY (USA). Two distinctive characteristics that are critical to this alga's survival in a benthic biofilm are its elaborate cell morphology and extracellular matrix (ECM). In this study, ultrastructural, immunocytochemical, and experimental methodologies were employed in order to elucidate the cellular characteristics that are critical for survival in a biofilm. The ECM consists of a thick, outwardly lobed cell wall (CW), which contains a patterned network of structurally complex pores. Each pore consists of a narrow channel, terminating internally at a bulb that invaginates localized regions of the plasma membrane. The outer region of the pore contains arabinogalactan protein-like and extensin epitopes that are likely involved in adhesion mechanisms of the cell. External to the CW is the extracellular polymeric substance that is employed in ensheathment of the cell to the substrate and in gliding motility. The architectural design/biochemical make-up of the CW and a secretory system that encompasses the coordinated activities of the endomembrane and cytomotile/cytoskeletal systems provide the organism with effective mechanisms to support life within the biofilm complex. 相似文献
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KEITH F. LEWIN JOHN NAGY W. ROBERT NETTLES DAVID M. COOLEY ALISTAIR ROGERS † 《Global Change Biology》2009,15(2):388-395
A direct comparison of treatment uniformity and CO2 use of pure and prediluted free-air CO2 enrichment (FACE) systems was conducted in a forest ecosystem. A vertical release pure CO2 fumigation system was superimposed on an existing prediluted CO2 fumigation system and operated on alternate days. The FACE system using prediluted CO2 fumigation technology exhibited less temporal and spatial variability than the pure CO2 fumigation system. The pure CO2 fumigation system tended to over-fumigate the upwind portions of the plot and used 25% more CO2 than the prediluted CO2 fumigation system. The increased CO2 use by the pure CO2 system was exacerbated at low wind speeds. It is not clear if this phenomenon will also be observed in plots with smaller diameters and low-stature vegetation. 相似文献
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MERCEDES MARTIN‐CERECEDA EMILY C. ROBERTS EMMA C. WOOTTON ELISA BONACCORSO PATRICIA DYAL ALMUDENA GUINEA DALE ROGERS CHRIS J. WRIGHT GIANFRANCO NOVARINO 《The Journal of eukaryotic microbiology》2010,57(2):159-170
ABSTRACT. Marine goniomonads have a worldwide distribution but ultrastructural information has not been available so far. An isolate of the heterotrophic marine nanoflagellate Goniomonas (G. aff. amphinema) from North Wales (UK) has been studied, providing information on its morphology and cellular structure using video, electron, laser scanning confocal microscopy (LSCM), and atomic force microscopy. Here, we describe a new feature, a granular area, potentially involved in particle capture and feeding. The binding of the lectin wheat germ agglutinin to the granular area of cells with discharged ejectisomes indicates the adhesive nature of this novel feature. The presence of a microtubular intracellular cytopharynx, apparently also used for feeding, has been revealed by LSCM. The small subunit rRNA gene of the isolate has been sequenced (1,788 bp). Phylogenetic results corroborate significant genetic divergence within the marine members of Goniomonas. This work highlights the need for integrated morphological, ultrastructural, and molecular investigation when describing and studying heterotrophic nanoflagellates. 相似文献
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E. A. AINSWORTH P. A. DAVEY G. J. HYMUS C. P. OSBORNE A. ROGERS H. BLUM J. NÖSBERGER & S. P. LONG 《Plant, cell & environment》2003,26(5):705-714
Photosynthesis is commonly stimulated in grasslands with experimental increases in atmospheric CO2 concentration ([CO2]), a physiological response that could significantly alter the future carbon cycle if it persists in the long term. Yet an acclimation of photosynthetic capacity suggested by theoretical models and short‐term experiments could completely remove this effect of CO2. Perennial ryegrass (Lolium perenne L. cv. Bastion) was grown under an elevated [CO2] of 600 µmol mol?1 for 10 years using Free Air CO2Enrichment (FACE), with two contrasting nitrogen levels and abrupt changes in the source : sink ratio following periodic harvests. More than 3000 measurements characterized the response of leaf photosynthesis and stomatal conductance to elevated [CO2] across each growing season for the duration of the experiment. Over the 10 years as a whole, growth at elevated [CO2] resulted in a 43% higher rate of light‐saturated leaf photosynthesis and a 36% increase in daily integral of leaf CO2 uptake. Photosynthetic stimulation was maintained despite a 30% decrease in stomatal conductance and significant decreases in both the apparent, maximum carboxylation velocity (Vc,max) and the maximum rate of electron transport (Jmax). Immediately prior to the periodic (every 4–8 weeks) cuts of the L. perenne stands, Vc,max and Jmax, were significantly lower in elevated than in ambient [CO2] in the low‐nitrogen treatment. This difference was smaller after the cut, suggesting a dependence upon the balance between the sources and sinks for carbon. In contrast with theoretical expectations and the results of shorter duration experiments, the present results provide no significant change in photosynthetic stimulation across a 10‐year period, nor greater acclimation in Vc,max and Jmax in the later years in either nitrogen treatment. 相似文献
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