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showing 10 items of 404 documents
Conséquences écologiques et évolutives du flux de gènes entre Brassica napus transgénique et ses apparentés sauvages
2010
In the framework of commercial release for transgenic crops with novel traits, consequences of gene flow and introgression are still one main concern. I explored the ecological and evolutionary consequences of gene flow between oilseed rape (Brassica napus) and its wild relatives, brown mustard (B. juncea) and wild radish (Raphanus raphanistrum), through several experiments carried out in greenhouse, common garden and field in Beijing and Dijon. First, I revised a comprehensive review of the literature about gene flow and its effect on plant fitness in the Brassiceae. Second, I investigated the effects on gene flow of seed size of hybrids between Bt-transgenic oilseed rape and mustard. Smal…
Dynamique et assemblage des communautés adventices : Approche par modélisation statistique
2011
To develop solutions for a productive and sustainable agriculture, principles, theories, andmethods of ecology may contribute to understand the biological processes governing the agroecosystem.The present case study was based on data collected by a network of observatories of weeds covering the whole of France (‘Biovigilance Flore’) and aimed at establishing forrules governing the assemblage and dynamics of weed communities in fields grown with annual crops. We particularly studied the possible relationships between species within acommunity, as well as the relationships between communities and their environment. Analyses were based on species abundances to take account of their effect on c…
Le réchauffement climatique diminue-t-il le risque de dégâts par le gel pour les cultures de climat tempéré ?
2014
Does global warming reduce the freezing injury risk to temperate climate crops? Winter crop response to a temperature increase is complex. Recent works point out, for cold climate vegetation, a paradoxical increase in freezing injury in a warming climate. Complementary works are needed to support these results for winter crops in temperate areas. To achieve this goal, five climatic records spanning a fifty years-long period for both daily minimum and maximum temperatures were analyzed with a model predicting frost hardiness and freezing damage for the winter pea crop. The methodological approach was based on three main steps: 1) the climate warming analysis of the 1987/1988 temperature shif…
Fungal ecology on grapes
2010
Microbial population of grapes is important from a technological point of view because it determines the quality of wine. But few studies have focused on fungal populations of grapes. A better knowledge of the fungal diversity on grapes, particularly as concerns species responsible for wine defects, may help efforts to control their development.We report the development of a PCR ITS-RFLP method as a fast and easy technique for identifying species of fungal genera present on grapes. By this methode, 41 different fungal species among 43 studied species belonging to 11 genera were characterized at the species level. Only P. thomii remained indistinguishable from P. glabrum. Using this PCR-ITS-…
Modification de la composition lipidique membranaire chez les bactéries lactiques en conditions de stress : étude du rôle physiologique des Acides Gr…
2010
The results obtained in this work have shown that in both lactic acid bacteria models, L. lactis subsp. cremoris and O. oeni, transcription of the cfa gene, encoding the Cfa synthase is stimulated when cells enter stationary phase of growth or when the cells are grown under stress conditions (acidic or presence of ethanol in the medium). The role of the CFAs has been apprehended by the comparative physiological analysis of the parental strain L. lactis subsp. cremoris and a Δcfa mutant generated in this strain. The high percentages of survival obtained in strains grown at pH 5.0 and undergoing acid stress (pH 3.0) prove that the cyclopropanation of unsaturated fatty acids is not essential t…
Etude des transferts de petites molécules au travers des films comestibles encapsulant des substances actives (arômes)
2010
The aim of this work was a better understanding of the effect of the aroma and/or lipid particles incorporation on the structure and physico-chemical properties of film-forming matrices based on iota-carrageenan or sodium alginate. Microstructure, emulsion granulometry, thermal and mechanical properties were assessed as a function of n-hexanal and/or lipid presence. Barrier efficiencies to water, n-hexanal and D-limonene at liquid and vapour states, and to 6 other aroma vapours (ethyl esters, alcohols, keton) have been measured. When n-hexanal is added in the carrageenan matrix, it modifies the gelation process which induces a more homogeneous structure but a lower mechanical resistance, a …
Perception de la qualité du vin par les consommateurs
2011
In the recent years the wine consumption tends to decline, causing a world wine production surplus. Therefore, the wineries want to diversify their production to wines more qualitative and therefore more expensive. Thus, it is important to understand how the consumers perceived the wine quality. This work proposes a questionnaire measuring the perceived complexity of the wine. It demonstrated a strong link between the perception of the complexity and quality of a wine. The wines which are perceived like qualitative are wines concentrated in aromas persistent for the sensory point of view. Moreover, the sensory perception of quality is more correlated with the quality displayed by the market…
Early biological factors and outcome in very preterm infants
2013
Our aim was to identify early biochemical abnormalities associated with adverse outcome in very preterm infants. Based on an 8-year population-study for assessing the outcome in 1067 very preterm babies admitted to the neonatal intensive care unit of Dijon university hospital, two research axes were explored: 1) the impact of plasma chloride abnormalities on neurological morbidities; 2) the association between hypoproteinemia on the first day of life (D1) and adverse outcome. These issues were assessed by 4 studies, performed on the initial population and on 3 other cohorts.We found that hyperchloremia results in severe metabolic acidosis during the first 7-10 days of life, but this is not …
Locomotion et franchissement d'obstacles après lésion cérébrale : étude cinématique chez le rat
2010
Although the rat has become the favourite animal model in preclinical researches on locomotion, studies designed to assess the strategy used by rats to avoid obstacle avoidance are lacking in rats. Using an optoelectronic 3D motion analysis system, we have, therefore, compared the step pattern, timing and length variables of locomotor cycles, trajectories and joint angles values of limbs when rats stepped between and overcame obstacles (3 cm-height) fixed on a treadmill belt (25 cm/s). Motion of all the four limbs was serially recorded for a 10 weeks long-period in adult animals with an initial age of 11 weeks. The results show that obstacle avoidance results in disruption of the basic step…
Study of mechanisms of action of an immunotherapy by triacyl lipid A in humans
2013
Immunotherapy acting at the primary tumor site and preventing the development of metastases is one of the strategies for treatment of patients with cancer. To improve the efficiency of the latter, it is necessary to understand how it induces tumor cell death. In the laboratory, it was observed the cure of PROb tumors in rats BDIX by the triacyl lipid A. It has been shown that this effect involved the immune system involving interactions with TLRs present in many tumor cells and innate immunity cells such as neutrophils.In this work, we investigated the possible involvement of neutrophils in the antitumor activity of triacyl lipid A in humans.In a Phase 1 study in patients with refractory so…