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101.
102.
Each species generally has a close relationship with one or more habitats and can therefore be classified as either specialist or generalist. We studied whether specialist and generalist species are spatially distributed independently of each other. Repeating the analysis for 100 of the most frequent terrestrial bird species recorded over the 10 000 sampled sites of the French Breeding Bird survey, we found that specialists were more abundant if the rest of the community was specialized, and that the inverse was also true. This pattern was far subtler than just a simple dichotomy: most species actually presented a maximum abundance at a value of community specialization similar to their own level of specialization. Bird communities appear very well defined along a specialist–generalist gradient. We believe this pattern becomes more apparent with habitat degradation. The consequences on both ecological services and community resilience may well be considerable. 相似文献
103.
Susanna-Assunta Sansone Daniel Schober Helen J. Atherton Oliver Fiehn Helen Jenkins Philippe Rocca-Serra Denis V. Rubtsov Irena Spasic Larisa Soldatova Chris Taylor Andy Tseng Mark R. Viant 《Metabolomics : Official journal of the Metabolomic Society》2007,3(3):249-256
In this article we present the activities of the Ontology Working Group (OWG) under the Metabolomics Standards Initiative
(MSI) umbrella. Our endeavour aims to synergise the work of several communities, where independent activities are underway
to develop terminologies and databases for metabolomics investigations. We have joined forces to rise to the challenges associated
with interpreting and integrating experimental process and data across disparate sources (software and databases, private
and public). Our focus is to support the activities of the other MSI working groups by developing a common semantic framework
to enable metabolomics-user communities to consistently annotate the experimental process and to enable meaningful exchange
of datasets. Our work is accessible via a public webpage and a draft ontology has been posted under the Open Biological Ontology
umbrella. At the very outset, we have agreed to minimize duplications across omics domains through extensive liaisons with
other communities under the OBO Foundry. This is work in progress and we welcome new participants willing to volunteer their
time and expertise to this open effort.
See the MSI Ontology Working Group website for a complete list of members and contributors. Web URL: 相似文献
104.
105.
M. Brancourt-Hulmel J. -B. Denis C. Lecomte 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(2):285-298
Genotype-environment interaction has been analyzed in a winter-wheat breeding network using bi-additive factorial regression
models. This family of models generalizes both factorial regression and biadditive (or AMMI) models; it fits especially well
when abundant external information is available on genotypes and/or environments. Our approach, focused on environmental characterization,
was performed with two kinds of covariates: (1) deviations of yield components measured on four probe genotypes and (2) usual
indicators of yield-limiting factors. The first step was based on the analysis of a crop diagnosis on four probe genotypes.
Difference of kernel number to a threshold number (DKN) and reduction of thousand-kernel weight from a potential value (RTKW)
were used to characterize the grain-number formation and the grain-filling periods, respectively. Grain yield was analyzed
according to a biadditive factorial regression model using eight environmental covariates (DKN and RTKW measured on each of
four probe genotypes). In the second step, the usual indicators of yield-limiting factors were too numerous for the analysis
of grain yield. Thus a selection of a subset of environmental covariates was performed on the analysis of DKN and RTKW for
the four probe genotypes. Biadditive factorial regression models involved environmental covariates related to each deviation
and included environmental main effect, sum of water deficits, an indicator of nitrogen stress, sum of daily radiation, high
temperature, pressure of powdery mildew and lodging. The correlations of each environmental covariate to the synthetic variates
helped to discard those poorly involved in interaction (with | correlation | <0.3). The grain yield of 12 genotypes was interpreted
with the retained covariates using biadditive factorial regression. The models explained about 75% of the interaction sums
of squares. In addition, the biadditive factorial regression biplot gave relevant information about the interaction of the
genotypes (interaction pattern and sensitivities to environmental covariates) with respect to the environmental covariates
and proved to be interesting for such an approach.
Received: 8 March 1999 / Accepted: 29 July 1999 相似文献
106.
Sandrine Théoleyre Damien Masson Marc G. Denis 《Biochemical and biophysical research communications》2010,394(3):453-458
Peroxisome proliferator-activated receptor gamma (PPARγ) ligands have been shown to possess anti-proliferative effects in many types of cancer. In clear cell renal cell carcinoma (CCRCC), the targets involved in these effects are not known. In this study, we demonstrated that, in CCRCC cell lines, the endogenous PPARγ ligand 15-deoxy-Δ12,14-prostaglandin J2 (15dPGJ2) induces the expression, both at the mRNA and the protein levels, of the HtrA3 gene. This gene belongs to the High-Temperature Requirement Factor A family of serine proteases that repress signaling by TGF-β family members and inhibit cell migration. Rosiglitazone or ciglitazone, synthetic PPARγ agonists, did not induce HtrA3 expression, and the PPARγ antagonist GW9662 did not prevent 15dPGJ2 induction, suggesting that the up-regulation of HtrA3 by 15dPGJ2 is independent of PPARγ. The MEK/ERK inhibitor PD98059 dramatically repressed HtrA3 induction. Altogether, these data indicate that 15dPGJ2 is able to stimulate the expression of HtrA3 through an indirect mechanism involving the MEK/ERK pathway but independent of PPARγ. Our results provide a better understanding of the mechanisms involved in the regulation of HtrA3, a potential tumor suppressor gene. 相似文献
107.
Konka Veeranjaneyulu Denis Charlebois Christophe N. N'soukpoé-Kossi Roger M. Leblanc 《Photosynthesis research》1992,34(2):271-278
Sulfite treatment of pea leaf disks in light caused a significant decrease in the relative quantum yield of photosynthetic oxygen evolution and energy storage (ES) as measured by photoacoustic (PA) spectroscopy. The inhibition was concentration dependent and was less in darkness than in light, indicating light-dependent inhibitory site(s) on the photosynthetic electron transport chain. Further, in darksulfite-treated leaves, the energy storage was more affected than the relative quantum yield of oxygen evolution, suggesting that photophosphorylation and/or cyclic electron transport around PS I are sites of sulfite action in darkness. The Rfd values, the ratio of fluorescence decrease (fd) to the steady-state fluorescence (fs), decreased significantly in leaves treated with sulfite in light but were not affected in dark-treated ones, confirming the photoacoustic observations. Similarly, the ratio of variable fluorescence (Fv) to maximum fluorescence (Fm), a measure of PS II photochemical efficiency, was affected by sulfite treatment in light and not changed by treatment in darkness. An attempt was made to explain the mechanism of sulfite action on photosynthetic electron transport in light and in darkness.Abbreviations APT
amplitude of photothermal signal
- Aox
amplitude of oxygen signal
- ES
energy storage
- fd
fluorescence decrease
- fs
steady-state fluorescence
- Fm
maximum fluorescence
- Fv
variable fluorescence
- PA
photoacoustic(s) 相似文献
108.
109.
Gazanion E Vergnes B Seveno M Garcia D Oury B Ait-Oudhia K Ouaissi A Sereno D 《Parasitology international》2011,60(1):19-24
To improve the management of leishmaniasis, new drugs and/or alternative therapeutic strategies are required. Combination therapy of antileishmanial drugs is currently considered as one of the most rational approaches to lower treatment failure rate and limit drug resistance spreading. Nicotinamide (NAm), also known as vitamin B3 that is already is used in human therapy, exerts in vitro antileishmanial activity. Drug combination studies, performed on L. infantum axenic amastigotes, revealed that NAm significantly improves the antileishmanial activity of trivalent antimony in a synergistic manner while it shows additive activity with amphotericin B and slightly antagonizes pentamidine activity. NAm also significantly increases the toxicity of pentavalent antimony against the intracellular forms of L. infantum, L. amazonensis and L. braziliensis. The potential of NAm to be used as adjuvant during leishmaniasis chemotherapy is further discussed. 相似文献
110.
Production of Aseptic Spores of Vesicular-Arbuscular Endophytes and Their Viability After Chemical and Physical Stress 总被引:3,自引:1,他引:3 下载免费PDF全文
The survival of germinating spores of vesicular-arbuscular endophytes after treatments with oxidizing agents, antibiotics, moist heat, ultrasonic radiation, and ultraviolet radiation was compared with that of their contaminating microbes. Spores of three species were rapidly decontaminated by treatment with 0.42% (wt/vol) chlorine available from 5.0% (wt/vol) chloramine-T at 30°C for 20 to 40 min depending on the species and the soil from which they were extracted. This treatment did not change spore viability. The survival of spores was reduced by exposure for 20 min to 1.11% chlorine at 30°C for Glomus caledonius or at 35°C for Acaulospora laevis. Growth of any bacteria surviving treatment with oxidizing agents was inhibited by 100 μg of chloramphenicol per ml in agar; however, spore germination and germ tube growth were reduced only by concentrations greater than 200 μg/ml in agar. Spore germination was decreased by concentration of pimaracin, which controlled fungal growth. The spores survived moist heat at 40°C for 80 min, 55°C for 10 min, and 60°C for less than 1 min. The viability of spores was unaffected by ultrasonic irradiation for up to 4 min. Spores of G. caledonius and A. laevis were extremely resistant to ultraviolet radiation. Their viability was unaffected by exposure to 5 × 108 ergs cm−2 from an ultraviolet source of 253.7nm. The spores had very thick, pigmented walls, and the possibility that these provided some protection against the physical and chemical treatments is discussed. The degree of physiological damage to the spores caused by the treatments demonstrated some adverse effects of basic laboratory procedures. This information, together with that on the comparative sensitivity of contaminating microbes to the treatments, was used in the development of protocol for producing large numbers of uncontaminated spores. 相似文献