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21.
Kealohanuiopuna M. Kinney Gregory P. Asner Susan Cordell Oliver A. Chadwick Katherine Heckman Sara Hotchkiss Marjeta Jeraj Ty Kennedy-Bowdoin David E. Knapp Erin J. Questad Jarrod M. Thaxton Frank Trusdell James R. Kellner 《PloS one》2015,10(6)
We used measurements from airborne imaging spectroscopy and LiDAR to quantify the biophysical structure and composition of vegetation on a dryland substrate age gradient in Hawaii. Both vertical stature and species composition changed during primary succession, and reveal a progressive increase in vertical stature on younger substrates followed by a collapse on Pleistocene-aged flows. Tall-stature Metrosideros polymorpha woodlands dominated on the youngest substrates (hundreds of years), and were replaced by the tall-stature endemic tree species Myoporum sandwicense and Sophora chrysophylla on intermediate-aged flows (thousands of years). The oldest substrates (tens of thousands of years) were dominated by the short-stature native shrub Dodonaea viscosa and endemic grass Eragrostis atropioides. We excavated 18 macroscopic charcoal fragments from Pleistocene-aged substrates. Mean radiocarbon age was 2,002 years and ranged from < 200 to 7,730. Genus identities from four fragments indicate that Osteomeles spp. or M. polymorpha once occupied the Pleistocene-aged substrates, but neither of these species is found there today. These findings indicate the existence of fires before humans are known to have occupied the Hawaiian archipelago, and demonstrate that a collapse in vertical stature is prevalent on the oldest substrates. This work contributes to our understanding of prehistoric fires in shaping the trajectory of primary succession in Hawaiian drylands. 相似文献
22.
Carboxysomes are metabolic modules for CO(2) fixation that are found in all cyanobacteria and some chemoautotrophic bacteria. They comprise a semi-permeable proteinaceous shell that encapsulates ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and carbonic anhydrase. Structural studies are revealing the integral role of the shell protein paralogs to carboxysome form and function. The shell proteins are composed of two domain classes: those with the bacterial microcompartment (BMC; Pfam00936) domain, which oligomerize to form (pseudo)hexamers, and those with the CcmL/EutN (Pfam03319) domain which form pentamers in carboxysomes. These two shell protein types are proposed to be the basis for the carboxysome's icosahedral geometry. The shell proteins are also thought to allow the flux of metabolites across the shell through the presence of the small pore formed by their hexameric/pentameric symmetry axes. In this review, we describe bioinformatic and structural analyses that highlight the important primary, tertiary, and quaternary structural features of these conserved shell subunits. In the future, further understanding of these molecular building blocks may provide the basis for enhancing CO(2) fixation in other organisms or creating novel biological nanostructures. 相似文献
23.
Modulation of stress and virulence in Listeria monocytogenes 总被引:1,自引:0,他引:1
24.
In vivo phage display is a high-throughput method for identifying target ligands specific for different vascular beds. Targeting is possible due to the heterogeneous expression of receptors and other antigens in a particular vascular bed. Such expression is additionally influenced by the physiological or pathological status of the vasculature. In vivo phage display represents a technique that is usable in both, vascular mapping and targeted drug development. In this review, several important methodological aspects of in vivo phage display experiments are discussed. These include choosing an appropriate phage library, an appropriate animal model and the route of phage library administration. In addition, peptides or antibodies identified by in vivo phage display homing to specific types of vascular beds, including the altered vasculature present in several types of diseases are summarized. Still, confirmation in independent experiments and reproduction of identified sequences are needed for enhancing the clinical applicability of in vivo phage display research. 相似文献
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27.
Scott E. Wolkenberg Zhijian Zhao David D. Wisnoski William H. Leister Julie O’Brien Wei Lemaire David L. Williams Marlene A. Jacobson Cyrille Sur Gene G. Kinney Doug J. Pettibone Philip R. Tiller Sheri Smith Christopher Gibson Bennett K. Ma Stacey L. Polsky-Fisher Craig W. Lindsley George D. Hartman 《Bioorganic & medicinal chemistry letters》2009,19(5):1492-1495
Glycine transporter 1 (GlyT1) represents a novel target for the treatment of schizophrenia via the potentiation of glutamatergic NMDA receptors. The discovery of 4,4-disubstituted piperidine inhibitors of GlyT1 which exhibit improved pharmacokinetic properties, including oral bioavailability, is discussed. 相似文献
28.
The effects of acclimatization of microbial populations, compound concentration, and media pH on the biodegradation of low concentration dichloromethane emissions in biofiltration systems was evaluated. Greater than 98% removal efficiency was achieved for dichloromethane at superficial velocities from 1 to 1.5 m(3)/m(3). min (reactor residence times of 1 and 0.7 min, respectively) and inlet concentrations of 3 and 50 ppm Although acclimatization of microbial populations to toluene occurred within 2 weeks of operation start-up, initial dichloromethane acclimatization took place over a period of 10 weeks. This period was shortened to 10 days when a laboratory grown consortium of dichloromethane degrading organism, isolated from a previously acclimatized column, was introduced into fresh biofilter media. The mixed culture consisted to 12 members, which together were able to degrade dichloromethane at concentrations up to 500 mg/L. Only one member of the consortium was able to degrade dichloromethane were sustained for more than 4 months in a biofilter column receiving an inlet gas stream with 3 ppm(v) of dichloromethane acidification of the column and resulting decline in performance occurred when a 50-ppm(v) inlet concentration was used. A biofilm model incorporating first order biodegradation kinetics provided a good fit to observed concentration profiles, and may prove to be a useful tool for designing biofiltration systems for low concentration VOC emissions. (c) 1994 John Wiley & Sons, Inc. 相似文献
29.
Characterization and pathogenic potential of Listeria monocytogenes isolates from the smoked fish industry 总被引:3,自引:0,他引:3
Norton DM Scarlett JM Horton K Sue D Thimothe J Boor KJ Wiedmann M 《Applied and environmental microbiology》2001,67(2):646-653
This study was designed to evaluate the hypothesis that some of the Listeria monocytogenes subtypes associated with foods, specifically smoked fish, may have an attenuated ability to cause human disease. We tested this hypothesis by using two different approaches: (i) comparison of molecular subtypes found among 117 isolates from smoked fish, raw materials, fish in process, and processing environments with subtypes found among a collection of 275 human clinical isolates and (ii) the evaluation of the cytopathogenicity of industrial isolates. Ribotyping and PCR-restriction fragment length polymorphism typing of the hlyA and actA genes differentiated 23 subtypes among the industrial isolates and allowed classification of the isolates into three genetic lineages. A significantly higher proportion of human isolates (69.1%) than industrial isolates (36.8%) were classified as lineage I, which contains human sporadic isolates and all epidemic isolates. All other industrial isolates (63.2%) were classified as lineage II, which contains only human sporadic isolates. Lineage I ribotypes DUP-1038B and DUP-1042B represented a significantly higher proportion of the human isolates than industrial isolates (5.1%). Lineage II ribotypes DUP-1039C, DUP-1042C, and DUP-1045, shown previously to persist in the smoked fish processing environment, represented nearly 50% of the industrial isolates, compared to 7.6% of the human isolates. Representatives of each subtype were evaluated with a tissue culture plaque assay. Lineage I isolates formed plaques that were significantly larger than those formed by lineage II isolates. Isolates from the smoked fish industry representing three ribotypes formed no plaques or small plaques, indicating that they had an impaired ability to infect mammalian cells. While L. monocytogenes clonal groups linked to human listeriosis cases and outbreaks were isolated, our data also suggest that at least some L. monocytogenes subtypes present in ready-to-eat foods may have limited human-pathogenic potential. 相似文献
30.
Melissa Simpson Janet K Snell-Bergeon Gregory L Kinney Orit Lache Rachel Miller-Lotan Yefim Anbinder Marian J Rewers Andrew P Levy 《Cardiovascular diabetology》2011,10(1):1-7