Search results for "Luc"
showing 10 items of 4070 documents
Changes in carbohydrate metabolism in Plasmopara viticola-infected grapevine leaves.
2011
International audience; The oomycete Plasmopara viticola is responsible for downy mildew, a severe grapevine disease. In infected grapevine leaves, we have observed an abnormal starch accumulation at the end of the dark period, suggesting modifications in starch metabolism. Therefore, several complementary approaches, including transcriptomic analyses, measurements of enzyme activities, and sugar quantification, were performed in order to investigate and to understand the effects of P. viticola infection on leaf starch and-to a larger extent-carbohydrate metabolism. Our results indicate that starch accumulation is associated with an increase in ADP-glucose pyrophosphorylase (AGPase) activit…
Differential performance of a specialist and two generalist herbivores and their parasitoids on Plantago lanceolata
2011
The ability to cope with plant defense chemicals differs between specialist and generalist species. In this study, we examined the effects of the concentration of the two main iridoid glycosides (IGs) in Plantago lanceolata, aucubin and catalpol, on the performance of a specialist and two generalist herbivores and their respective endoparasitoids. Development of the specialist herbivore Melitaea cinxia was unaffected by the total leaf IG concentration in its host plant. By contrast, the generalist herbivores Spodoptera exigua and Chrysodeixis chalcites showed delayed larval and pupal development on plant genotypes with high leaf IG concentrations, respectively. This result is in line with t…
Impact of sewage pollution on two species of sea urchins in the Mediterranean Sea (Cortiou, France): radial asymmetry as a bioindicator of stress.
2015
9 pages; International audience; BackgroundThe surroundings of the Cortiou sewage are among the most polluted environments of the French Mediterranean Sea (Marseilles, France). So far, no studies have precisely quantified the impact of pollution on the development of organisms in this area.MethodsWe used a fluctuating asymmetry (FA) measure of developmental instability (DI) to assess environmental stress in two species of radially symmetric sea urchins (Arbacia lixula and Paracentrotus lividus). For six sampling sites (Cortiou, Riou, Maire, East Maire, Mejean, and Niolon), levels of FA were calculated from continuous and discrete skeletal measures of ambulacral length, number of pore pairs …
FLUCTUATING TEMPERATURE LEADS TO EVOLUTION OF THERMAL GENERALISM AND PREADAPTATION TO NOVEL ENVIRONMENTS
2013
Environmental fluctuations can select for generalism, which is also hypothesized to increase organisms' ability to invade novel environments. Here, we show that across a range of temperatures, opportunistic bacterial pathogen Serratia marcescens that evolved in fluctuating temperature (daily variation between 24°C and 38°C, mean 31°C) outperforms the strains that evolved in constant temperature (31°C). The growth advantage was also evident in novel environments in the presence of parasitic viruses and predatory protozoans, but less clear in the presence of stressful chemicals. Adaptation to fluctuating temperature also led to reduced virulence in Drosophila melanogaster host, which suggests…
Integrating fishing spatial patterns and strategies to improve high sea fisheries management
2018
Fishing activity in waters beyond national jurisdiction generates multiple management issues, such as data poor fisheries, management of straddling fish stocks and lack of impact assessments on deep-sea Vulnerable Marine Ecosystems (VMEs). Fishing strategy is the key to understanding and managing high seas fisheries, targeting highly migratory resources that are widely distributed. An international fleet, including Spanish flag bottom trawlers, operates along the Patagonian shelf in Southwest Atlantic waters, which includes an unregulated strip of continental shelf beyond national jurisdiction. The Spanish fleet’s fishing strategy was analyzed, and based on on-board observer data collected …
Study on the effects of several operational variables on the enzymatic batch saccharification of orange solid waste
2017
In this work, batch enzyme-aided extraction and enzymatic saccharification of blade-milled orange waste was studied. The operation variables for this process were thoroughly analysed. It was determined that batch runs with initial pH values of 5.0 and 5.2 controlled during the first hour, 50°C and 300-500r.p.m. agitation resulted in the best yields, with a limited total and partial first-order enzyme deactivation (for cellulases and polygalacturonidase, respectively). Orange peel waste (OPW) at 6.7% w/w dry solid, 0.22 filter paper units (FPU)/g DS and proportional activities of other enzymes led to over 40g/L free monosaccharides and global yields to glucose over 80%. When using 10.1% w/w …
Expression of xyloglucan endotransglucosylase/hydrolase (XTH) genes and XET activity in ethylene treated apple and tomato fruits.
2013
[EN] Xyloglucan endotransglucosylase/hydrolase (XTHs: EC 2.4.1.207 and/or EC 3.2.1.151), a xyloglucan modifying enzyme, has been proposed to have a role during tomato and apple fruit ripening by loosening the cell wall. Since the ripening of climacteric fruits is controlled by endogenous ethylene biosynthesis, we wanted to study whether XET activity was ethylene-regulated, and if so, which specific genes encoding ripening-regulated XTH genes were indeed ethylene-regulated. XET specific activity in tomato and apple fruits was significantly increased by the ethylene treatment, as compared with the control fruits, suggesting an increase in the XTH gene expression induced by ethylene. The 25 Sl…
Gray plumage color is more cryptic than brown in snowy landscapes in a resident color polymorphic bird
2020
Abstract Camouflage may promote fitness of given phenotypes in different environments. The tawny owl (Strix aluco) is a color polymorphic species with a gray and brown morph resident in the Western Palearctic. A strong selection pressure against the brown morph during snowy and cold winters has been documented earlier, but the selection mechanisms remain unresolved. Here, we hypothesize that selection favors the gray morph because it is better camouflaged against predators and mobbers in snowy conditions compared to the brown one. We conducted an online citizen science experiment where volunteers were asked to locate a gray or a brown tawny owl specimen from pictures taken in snowy and snow…
Incorporating Biotic Information in Species Distribution Models: A Coregionalized Approach
2021
In this work, we discuss the use of a methodological approach for modelling spatial relationships among species by means of a Bayesian spatial coregionalized model. Inference and prediction is performed using the integrated nested Laplace approximation methodology to reduce the computational burden. We illustrate the performance of the coregionalized model in species interaction scenarios using both simulated and real data. The simulation demonstrates the better predictive performance of the coregionalized model with respect to the univariate models. The case study focus on the spatial distribution of a prey species, the European anchovy (Engraulis encrasicolus), and one of its predator spe…
Do Australopithecus aos ciborgues. Estamos diante do fim da evolução humana?.
2020
Abstract Social implementation of post-humanism could affect the biological evolution of living beings and especially that of humans. This paper addresses the issue from the biological and anthropological-philosophical perspectives. From the biological perspective, reference is made first to the evolution of hominids until the emergence of Homo sapiens, and secondly, to the theories of evolution with special reference to their scientific foundation and the theory of extended heredity. In the anthropological-philosophical part, the paradigm is presented according to which human consciousness, in its emancipatory zeal against biological nature, must “appropriate” the roots of its physis to tr…