Atlas of protein sequence and structure

Atlas of protein sequence and structur

Desorption experiments and modeling of micropollutants on activated carbon in water phase: application to transient concentrations mitigation

Experimental studies and numerical modeling were conducted to assess the feasibility of a granular activated carbon column to buffer load variations of contaminants before wastewater treatment devices. Studies of cycles of adsorption, and more especially desorption, of methyldiethanolamine (MDEA) and 2,4-dimethylphenol (2,4-DMP) have been carried out on granular activated carbon (GAC). Dynamic variations of contaminants concentrations were run at several conditions of duration (peaks). GAC fixed-bed exhibited a stable adsorption/desorption capacity after undergoing two conditioning cycles. The study of pollution peaks revealed that attenuation is largely dependent on the targeted pollutant: 2.4 ± 0.5 % attenuation/cm of bed for MDEA and 6.0 ± 1.2 % attenuation/cm of bed for 2,4-DMP. Mass balances calculated from both injected and recovered pollutant during peaks were respected. Finally, a coupling of the linear driving force model and isotherms models was used to fit experimental data for both adsorption breakthrough curves and desorption curves. The model was used to predict adsorption and desorption behaviors of following cycles. Good agreement with experimental values was obtained

Quantification of biotic stresses on aerial parts of plants using Chlorophyll Fluorescence Imaging and Image Analysis

Image analysis is increasingly used in plant phenotyping. Among the various imaging techniques available for plant phenotyping, Chlorophyll Fluorescence Imaging is particularly su itable for the imaging of biotic and abiotic stresses on the aerial parts of plants. Numerous chlorophyll fluorescence parameters may be measured or calculated, but only some of them may provide useful contrasts for the quantification of a given stress on leaves. In the perspective of high throughput phenotyping of biotic stresses on plants, we developed automated procedures to identify Chlorophyll Fluorescence parameters of interest for the quantification of a given biotic stress on large image datasets. The outputs of the automated procedures enable: - the visualization of the whole dataset, by providing contact sheets for each of the chlorophyll fluorescence parameter tested. - the visualization of basic statistics : radial - plot, box - plot and Mann - Whitney tests based on the mean intensity of each parameters are provided to compare the various treatments performed. - images are clustered based on histograms associated to each images, thereby enabling the clustering of images leaves displaying leaves of si milar phytosanitary status. - the objective quantification of disease incidence on each leaf tested. The quantification can discriminate varois stages of symptom development such as necrotic tissues, wilted and chlorotic tissues, and impacted tissues that do not display any symptoms visible to the eye.

Microbial gardening in the ocean's twilight zone : Detritivorous metazoans benefit from fragmenting, rather than ingesting, sinking detritus

Funded by NERC NE/K001833/1 ‘Oceans 2025’Peer reviewedPublisher PD

Fixed-bed adsorption of toluene on high silica zeolites: experiments and mathematical modelling using LDF approximation and a multisite model

The adsorption of toluene (TOL) as a target volatile organic compound has been studied experimentally and modelled on various hydrophobic zeolites: Faujasite (FAU), ZSM-5 (Z) and Mordenite (MOR). The influence of the nature of the compensating cation (H+ or Na+) has also been investigated for ZSM-5 zeolite, which is known to possess three kinds of adsorption sites (sinusoidal channels, straight channels and intersections). Type I isotherms observed on FAU, Na-Z and MOR fitted well with the Langmuir model. A deviation from a type I isotherm was observed for H-Z, because of the structure of this zeolite. The Successive Langmuir Model was more successful to fit the ‘bump’ of the experimental curve than the Double Langmuir. Classical shapes were found for MOR, FAU and Na-Z breakthrough curves that were fitted with good accuracy using the Linear Driving Force (LDF) approximation. In the case of H-Z, a change of profile was observed during the dynamic adsorption and the differences seen between the Na-Z and H-Z behaviours were explained by the strong interactions between Na+ and adsorbed TOL at the intersection sites. The Na+ cations prevented reorientation of TOL molecules at the intersection and thereby avoided the filling of the sinusoidal channel segments. Thus, a specific model was developed for fitting the breakthrough curve of H-Z. The model developed took into account these two types of adsorption sites with the overall uptake for each site being given by an LDF approximation

Incidence des partenaires microbiens sur les interactions des insectes avec leur environnement biotique : approche comportementale des associations symbiotiques

Symbiotic associations between an eukaryotic host and a microbial symbiont are ubiquitous. Symbiosis is often associated with the modification of hosts’ phenotypes, referred to as extended phenotypes. The objective of this thesis is to better understand how extended phenotypes and in particular modulation of host behaviors caused by symbionts can influence the biotic interactions of insects. In particular, we focus on the effect of the symbiotic bacteria of a phytophagous insect, the pea aphid Acyrthosiphon pisum, on its relationships with its host plant and one of its natural enemies, the parasitoid Aphidius ervi. Our studies suggest a limited influence of Hamiltonella defensa and Regiella insecticola on host behaviors involved in foraging and plant selection. However, our results show that symbiotic microorganisms play an important role in aphid-natural enemy relationships. Aphids infected with H. defensa exhibit less defensive behaviors, while the protection phenotype and the costs associated with the symbiont vary from one symbiont species and strain to the other. These various works show that the impact of symbionts on behaviors is highly variable and depends on the host-symbiont association. This thesis provides a better understanding of the evolutionary forces involved in the dynamic of symbiont associations and as well as on the role of symbionts in the ecology and evolution of their host species.Les associations symbiotiques entre un hôte eucaryote et un ou plusieurs partenaires microbiens sont ubiquistes. La symbiose est souvent associée à la modification de nombreux phénotypes de l’espèce hôte, on parle alors de phénotypes étendus. L’objectif de cette thèse est de mieux comprendre en quoi les phénotypes étendus et en particulier la modification des comportements engendrés par les symbiotes microbiens peuvent influencer les interactions biotiques des insectes-hôtes. Plus particulièrement, nous nous sommes intéressés à l’incidence des bactéries symbiotiques facultatives d’un insecte phytophage, le puceron du pois Acyrthosiphon pisum, sur ses relations avec sa plante hôte et un de ses ennemis naturels principaux, le parasitoïde Aphidius ervi. Nos études menées sur des lignées de pucerons différant par leur composition symbiotique suggèrent une influence limitée de Hamiltonella defensa et de Regiella insecticola sur les comportements d’exploration et de choix lors des interactions entre les pucerons et leur plante hôte. En revanche, nos résultats montrent que les microorganismes symbiotiques jouent un rôle important dans les relations puceron-ennemi naturel. Les pucerons infectés par H. defensa présentent généralement moins de comportements de défense, alors que le phénotype de protection et les coûts associés au symbiote varient d’une espèce et d’une souche à l’autre. Ces différents travaux montrent que l’incidence des symbiotes sur les comportements est très variable et dépend de l’association hôte-symbiote considérée. Ce travail de thèse permet de mieux appréhender les forces évolutives impliquées dans la dynamique des symbiotes dans les populations d’hôte et apporte de nouveaux éclairages sur le rôle des microorganismes symbiotiques dans l’écologie et l’évolution des espèces hôtes