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61.
Multiple transcription start sites and alternative splicing in the methylenetetrahydrofolate reductase gene result in two enzyme isoforms 总被引:4,自引:0,他引:4
62.
63.
Plant functional traits capture species richness variations along a flooding gradient 总被引:1,自引:0,他引:1
Cyrille Violle Anne Bonis Manuel Plantegenest Christophe Cudennec Christian Damgaard Benoît Marion Didier Le Cœur Jan‐Bernard Bouzillé 《Oikos》2011,120(3):389-398
Local species coexistence is the outcome of abiotic and biotic filtering processes which sort species according to their trait values. However, the capacity of trait‐based approaches to predict the variation in realized species richness remains to be investigated. In this study, we asked whether a limited number of plant functional traits, related to the leaf‐height‐seed strategy scheme and averaged at the community level, is able to predict the variation in species richness over a flooding disturbance gradient. We further investigated how these mean community traits are able to quantify the strength of abiotic and biotic processes involved in the disturbance–productivity–diversity relationship. We thus tested the proposal that the deviation between the fundamental species richness, assessed from ecological niche‐based models, and realized species richness, i.e. field‐observed richness, is controlled by species interactions. Flooding regime was determined using a detailed hydrological model. A precise vegetation sampling was performed across 222 quadrats located throughout the flooding gradient. Three core functional traits were considered: specific leaf area (SLA), plant height and seed mass. Species richness showed a hump‐shaped response to disturbance and productivity, but was better predicted by only two mean community traits: SLA and height. On the one hand, community SLA that increased with flooding, controlled the disturbance‐diversity relationship through habitat filtering. On the other hand, species interactions, the strength of which was captured by community height values, played a strong consistent role throughout the disturbance gradient by reducing the local species richness. Our study highlights that a limited number of simple, quantitative, easily measurable functional traits can capture the variation in plant species richness at a local scale and provides a promising quantification of key community assembly mechanisms. 相似文献
64.
Fernández-Acero FJ Jorge I Calvo E Vallejo I Carbú M Camafeita E Garrido C López JA Jorrin J Cantoral JM 《Archives of microbiology》2007,187(3):207-215
Botrytis cinerea is a phytopathogenic fungus causing disease in a substantial number of economically important crops. In an attempt to identify putative fungal virulence factors, the two-dimensional gel electrophoresis (2-DE) protein profile
from two B. cinerea strains differing in virulence and toxin production were compared. Protein extracts from fungal mycelium obtained by tissue
homogenization were analyzed. The mycelial 2-DE protein profile revealed the existence of qualitative and quantitative differences
between the analyzed strains. The lack of genomic data from B. cinerea required the use of peptide fragmentation data from MALDI-TOF/TOF and ESI ion trap for protein identification, resulting
in the identification of 27 protein spots. A significant number of spots were identified as malate dehydrogenase (MDH) and
glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The different expression patterns revealed by some of the identified proteins
could be ascribed to differences in virulence between strains. Our results indicate that proteomic analysis are becoming an
important tool to be used as a starting point for identifying new pathogenicity factors, therapeutic targets and for basic
research on this plant pathogen in the postgenomic era. 相似文献
65.
An improved method for the isolation of rubella virus-like particles (RVLP) from cell culture supernatant of transfected Chinese hamster ovary (CHO24S) cells is described. It employs a combination of membrane filtration with sucrose gradient ultracentrifugation. It was found that staining the RVLP band with Coomassie brilliant blue G (CBB) resulted in the CBB crystals adsorbing RVLP. After ultracentrifugation (25,000 rpm, 3h, 4 degrees C) a sharp blue band with crystals (diameter 30-40 microm) was observed (at a density of 1.250 g/ml at 25 degrees C) in a 30-60% sucrose gradient. Using a combination of SDS-PAGE and Western blotting techniques, E1 rubella virus structural protein was detected only in the solutions derived from the sharp blue band. A decrease in crystal concentration a few millimeters above or below the main band was associated with a decrease in protein concentration. By dilution with a saturated ice-cold 30% sucrose solution it was possible to pellet the crystals by centrifugation (15,000 rpm, 10 min). SDS-PAGE showed a much higher concentration of RVLP structural protein in the pellet than in the supernatant. This RVLP-containing material is especially suitable for the preparation of rubella virus immunoblot stripes. 相似文献
66.
67.
G C Whittow C A Scammell J K Manuel D Rand M Leong 《Archives internationales de physiologie et de biochimie》1977,85(1):139-151
Six slow loris were exposed to air temperatures between 10 degrees C and 40 degrees C. Rectal temperature was stable (mean, 34.8 degrees C) at air temperatures between 17 degrees C and 31 degrees C; at higher air temperatures, the animals became hyperthermic. Oxygen consumption was minimal at air temperatures of 31.4-36.6 degrees C; the mean value (0.250 ml O2 g-1 h-1) was only 36% of the expected level for a eutherian Mammal. The slow loris increased its heat production at lower air temperatures. Thermal polypnea occurred in response to heat, and some of the animals were able to dissipate their entire metabolic heat production at lower air temperatures. Thermal polypnea occurred in response to heat, and some of the animals were able the combined thermal conductance of the tissues and haircoat was 73% of the predicted values. It was concluded that, in spite of its low metabolic rate, the slow loris had effective responses to moderate cold, and that, in addition, it was well adapted to a hot climate. 相似文献
68.
Treatment of Biogas Produced in Anaerobic Reactors for Domestic Wastewater: Odor Control and Energy/Resource Recovery 总被引:1,自引:0,他引:1
Adalberto Noyola Juan Manuel Morgan-Sagastume Jorge E. López-Hernández 《Reviews in Environmental Science and Biotechnology》2006,5(1):93-114
Anaerobic municipal wastewater treatment in developing countries has important potential applications considering their huge
lack of sanitation infrastructure and their advantageous climatic conditions. At present, among the obstacles that this technology
encounters, odor control and biogas utilization or disposal should be properly addressed. In fact, in most of small and medium
size anaerobic municipal treatment plants, biogas is just vented, transferring pollution from water to the atmosphere, contributing
to the greenhouse gas inventory. Anaerobic municipal sewage treatment should not be considered as an energy producer, unless
a significant wastewater flow is treated. In these cases, more than half of the methane produced is dissolved and lost in
the effluent so yield values will be between 0.08 and 0.18 N m3 CH4/kg COD removed. Diverse technologies for odor control and biogas cleaning are currently available. High pollutant concentrations
may be treated with physical-chemical methods, while biological processes are used mainly for odor control to prevent negative
impacts on the treatment facilities or nearby areas. In general terms, biogas treatment is accomplished by physico-chemical
methods, scrubbing being extensively used for H2S and CO2 removal. However, dilution (venting) has been an extensive disposal method in some small- and medium-size anaerobic plants
treating municipal wastewaters. Simple technologies, such as biofilters, should be developed in order to avoid this practice,
matching with the simplicity of anaerobic wastewater treatment processes. In any case, design and specification of biogas
handling system should consider safety standards. Resource recovery can be added to anaerobic sewage treatment if methane
is used as electron donor for denitrification and nitrogen control purposes. This would result in a reduction of operational
cost and in an additional advantage for the application of anaerobic sewage treatment. In developing countries, biogas conversion
to energy may apply for the clean development mechanism (CDM) of the Kyoto Protocol. This would increase the economic feasibility
of the project through the marketing of certified emission reductions (CERs). 相似文献
69.
Vázquez-Fernández MÁ Bermejo MR Fernández-García MI González-Riopedre G Rodríguez-Doutón MJ Maneiro M 《Journal of inorganic biochemistry》2011,105(12):1538-1547
The peroxidase and catalase activities of eighteen manganese-Schiff base complexes have been studied. A correlation between the structure of the complexes and their catalytic activity is discussed on the basis of the variety of systems studied. Complexes 1-18 have the general formulae [MnLn(D)2](X)(H2O/CH3OH)m, where Ln = L1-L13; D = H2O, CH3OH or Cl; m = 0-2.5 and X = NO3−, Cl−, ClO4−, CH3COO−, C2H5COO− or C5H11COO−. The dianionic tetradentate Schiff base ligands H2Ln are the result of the condensation of different substituted (OMe-, OEt-, Br-, Cl-) hydroxybenzaldehyde with diverse diamines (1,2-diaminoethane for H2L1-H2L2; 1,2-diamino-2-methylethane for H2L3-H2L4; 1,2-diamino-2,2-dimethylethane for H2L5; 1,2-diphenylenediamine for H2L6-H2L7; 1,3-diaminopropane for H2L8-H2L11; 1,3-diamino-2,2-dimethylpropane for H2L12-H2L13). The new Mn(III) complexes [MnL1(H2O)Cl](H2O)2.5 (2), [MnL2(H2O)2](NO3)(H2O) (4), [MnL6(H2O)2][MnL6(CH3OH)(H2O)](NO3)2(CH3OH) (8), [MnL6(H2O)(OAc)](H2O) (9) and [MnL7(H2O)2](NO3)(CH3OH)2 (12) were isolated and characterised by elemental analysis, magnetic susceptibility and conductivity measurements, redox studies, ESI spectrometry and UV, IR, paramagnetic 1H NMR, and EPR spectroscopies. X-ray crystallographic studies of these complexes and of the ligand H2L6 are also reported. The crystal structures of the rest of the complexes have been previously published and herein we have only revised their study by those techniques still not reported (EPR and 1H NMR for some of these compounds) and which help to establish their structures in solution. Complexes 1-12 behave as more efficient mimics of peroxidase or catalase in contrast with 13-18. The analysis between the catalytic activity and the structure of the compounds emphasises the significance of the existence of a vacant or a labile position in the coordination sphere of the catalyst. 相似文献
70.
Echevarría-Machado I Martínez-Estévez M Muñoz-Sánchez JA Loyola-Vargas VM Hernández-Sotomayor SM De Los Santos-Briones C 《Molecular biotechnology》2007,35(3):297-309
We have previously reported that Catharanthus roseus transformed roots contain at least two phosphatidylinositol 4,5-bisphosphate-phospholipase C (PLC) activities, one soluble
and the other membrane associated. Detergent, divalent cations, and neomycin differentially regulate these activities and
pure protein is required for a greater understanding of the function and regulation of this enzyme. In this article we report
a partia purification of membrane-associated PLC. We found that there are at least two forms of membrane-associated PLC in
transformed roots of C. roseus. These forms were separated on the basis of their affinity for heparin. One form shows an affinity for heparin and elutes
at approx 600 mM KCl. This form has a molecular mass of 67 kDa by size exclusion chromatography and Western blot analysis, whereas the other
form does not bind to heparin and has a molecular mass of 57 kDa. Possible differential regulation of these forms during transformed
root growth is discussed. 相似文献