Search results for "flu"
showing 10 items of 16583 documents
Oxygen transmittance correction for solar-induced chlorophyll fluorescence measured on proximal sensing: Application to the NASA-GSFC fusion tower
2017
Since oxygen (O 2 ) absorption of light becomes more pronounced at higher pressure levels, even a few meters distance between the target and the sensor can strongly affect canopy-leaving Solar-Induced chlorophyll Fluorescence (SIF) retrievals. This study was conducted to quantify the consequent error propagation and the impact of ignoring oxygen absorption effects on proximal sensing SIF measurements based on the O 2 -A absorption band with field-acquired and simulated data. It was demonstrated that the uncorrected oxygen transmittance between target and sensor distance of 10 m can lead to SIF relative errors ranging from 66% to higher than 100% when using a Spectral Fitting (SF) technique …
Behavior of plant plasma membranes under hydrostatic pressure as monitored by fluorescent environment-sensitive probes.
2010
International audience; We monitored the behavior of plasma membrane (PM) isolated from tobacco cells (BY-2) under hydrostatic pressures up to 3.5 kbar at 30 °C, by steady-state fluorescence spectroscopy using the newly introduced environment-sensitive probe F2N12S and also Laurdan and di-4-ANEPPDHQ. The consequences of sterol depletion by methyl-β-cyclodextrin were also studied. We found that application of hydrostatic pressure led to a marked decrease of hydration as probed by F2N12S and to an increase of the generalized polarization excitation (GPex) of Laurdan. We observed that the hydration effect of sterol depletion was maximal between 1 and 1.5 kbar but was much less important at hig…
Genome reduction and potential metabolic complementation of the dual endosymbionts in the whitefly Bemisia tabaci
2015
Background The whitefly Bemisia tabaci is an important agricultural pest with global distribution. This phloem-sap feeder harbors a primary symbiont, “Candidatus Portiera aleyrodidarum”, which compensates for the deficient nutritional composition of its food sources, and a variety of secondary symbionts. Interestingly, all of these secondary symbionts are found in co-localization with the primary symbiont within the same bacteriocytes, which should favor the evolution of strong interactions between symbionts. Results In this paper, we analyzed the genome sequences of the primary symbiont Portiera and of the secondary symbiont Hamiltonella in the B. tabaci Mediterranean (MED) species in orde…
Spatiotemporal patterns in methane flux and gas transfer velocity at low wind speeds: Implications for upscaling studies on small lakes
2016
Lakes contribute significantly to the global natural emissions of methane (CH4) and carbon dioxide. However, to accurately incorporate them into the continental carbon balance more detailed surveys of lacustrine greenhouse gas emissions are needed, especially in respect to spatiotemporal variability and to how this affects the upscaling of results. We investigated CH4 flux from a small, wind-shielded lake during 10 field trips over a 14 month period. We show that floating chambers may be used to calibrate the relationship between gas transfer velocity (k) and wind speed at 10 m height (U10) to the local system, in order to obtain more accurate estimates of diffusive CH4 flux than by applyin…
Colonization of adventitious roots ofMedicago truncatulabyPseudomonas fluorescensC7R12 as affected by arbuscular mycorrhiza
2008
Pseudomonas fluorescens C7R12 was previously shown to promote colonization of Medicago truncatula roots by Glomus mosseae BEG12. To gain more insight into the interaction between C7R12 and BEG12, the cell organization of C7R12 was characterized on adventitious roots mycorrhized or not with BEG12 and on extraradical hyphae. Bacterial cell observations were made using the immuno-fluorescence technique and confocal laser scanning microscopy. Five types of cell organization, so-called organization types (OT), were identified: small or large single cells, cells by pair and cells in microcolonies or in strings. The frequencies of each OT on the roots were expressed as the percentage of observatio…
Performance of a membrane-coupled high-rate algal pond for urban wastewater treatment at demonstration scale
2020
[EN] The objective of this study was to evaluate the performance of an outdoor membrane-coupled high-rate algal pond equipped with industrial-scale membranes for treating urban wastewater. Decoupling biomass retention time (BRT) and hydraulic retention time (HRT) by membrane filtration resulted in improved process efficiencies, with higher biomass productivities and nutrient removal rates when operating at low HRTs. At 6 days of BRT, biomass productivity increased from 30 to 66 and to 95 g.m(-3).d(-1) when operating at HRTs of 6, 4 and 2.5 days, respectively. The corresponding nitrogen removal rates were 4, 8 and 11 g N.m(-3).d(-1) and the phosphorous removal rates were 0.5, 1.3 and 1.6 g P…
Different bacteria can enhance the micropropagation response of Cotoneaster lacteus (Rosaceae)
1998
C. MONIER, E. BOSSIS, C. CHABANET AND R. SAMSON. 1998. Cotoneaster species are widely used ornamental shrubs, and research is under way to select genotypes which are more resistant to fire blight by somaclonal variation. During the establishment of micropropagation, one genotype, Cotoneaster lacteus, showed the development of endogenous bacterial contaminants. Two strains were isolated from in vitro explants: Bacillus pumilus and Alcaligenes faecalis. These two strains, and some Pseudomonas fluorescens and Ps. putida, promoted in vitro multiplication and rooting of explants. In Pseudomonas strains, rooting enhancing capacity appeared to be related to indole-3-acetic acid (IAA) production, a…
Does air pollution influence the success of species translocation? Trace elements, ultrastructure and photosynthetic performances in transplants of a…
2020
Abstract Species translocation can be considered as a primary conservation strategy with reference to in situ conservation. In the case of lichens, translocations often risk to fail due stress factors associated with unsuitable receptor sites. Considering the bioecological characteristics of lichens, air pollution is among the most limiting stress factors. In this study, the forest macrolichen Lobaria pulmonaria was used as a model to test the hypothesis that the translocation of sensitive lichens is effective only in unpolluted environments. At purpose, 500 fragments or whole thalli were translocated in selected beech forests of Central Europe (the Western Carpathians, Slovakia) where the …
Insecticide residues in cotton soils of Burkina Faso and effects of insecticides on fluctuating asymmetry in honey bees (Apis mellifera Linnaeus).
2011
8 pages; International audience; Four insecticides (acetamiprid, cypermethrin, endosulfan and profenofos) are used quarterly in the cotton-growing areas of Burkina Faso, West Africa. These insecticides were investigated in soils collected from traditionally cultivated and new cotton areas. Also, the effects of insecticide exposure on the developmental instability of honey bees, Apis mellifera, were explored. In soil samples collected three months after insecticide treatments, endosulfan and profenofos concentrations varied in the range of 10-30μgkg(-1) in the traditionally cultivated zones and 10-80μgkg(-1) in the new cotton zones, indicating a pollution of agricultural lands. However, only…
Southern and fluorescent in situ hybridization detect three RAPD-generated PCR products useful as introgression markers in Petunia
1999
Fluorescent in situ hybridization (FISH) was used to reveal the intrachromosomal organization of 11 RAPD markers localized on the genetic map of Petunia hybrida. The cloned RAPD markers were analyzed by means of Southern hybridization to determine their level of sequence repetition and their specificity in different Petunia species with 2n=14 and 18 chromosomes. The same probes were then used in FISH experiments. Most of the RAPD clones studied showed high sequence repetition and no species specificity. Moreover, FISH analysis showed that these probes could belong to multilocus families as evidenced by the multiple FISH signals dispersed throughout the genome and present on every chromosome…