Crystal Structure of the Human Natural Killer Cell Activating Receptor KIR2DS2 (CD158j)

Killer cell Ig-like receptors (KIRs) regulate the function of human natural killer and T cell subsets. A feature of the KIR locus is the clustering of homologous genes encoding for inhibitory and activating KIR. Inhibitory and activating KIR differ for ligand specificities and/or affinities. In particular, we show here with KIR tetramers that activating KIR2DS2 does not bind HLA-Cw3 molecules recognized by inhibitory KIR2DL2, despite 99% extracellular amino acid identity. We also report the 2.3-Å structure of KIR2DS2, which reveals subtle displacements of two residues (Tyr45 and Gln71) involved in the interaction of KIR2DL2 with HLA-Cw3. These results show that KIR molecules cannot tolerate any variability in their three-dimensional structure without altering their MHC class I recognition capacities. Therefore, the mode of recognition used by KIR largely differs from the conformational changes that characterize T cell receptor or NKG2D interaction with their respective ligands

Survey of protozoa and metazoa populations in wastewater treatment plants by image analysis and discriminant analysis

The biota present in the activated sludge of a wastewater treatment plant are mainly composed of bacteria, Protozoa and Metazoa. The Protozoa and Metazoa species are important micro-organisms taking part in the ecosystem balance in wastewater treatment plants and are quite sensitive to physical, chemical and operational processes. Several authors have established relationships between the predominance of certain species or groups and some variables of the plant. Such analysis demands the identification and quantification of the different species, which requires skilled workers, specializing in zoology or protozoology, and is time-consuming. To overcome those problems, semi-automatic image analysis and discriminant analysis were carried out for the identification procedures. The overall results were very promising in terms of Protozoa and Metazoa group recognition and of survey of plant conditions. Copyright 2004 John Wiley & Sons, Ltd.Financial support for the co-operation between the Portuguese (Braga) and French (Nancy) teams was provided by the French Embassy in Portugal and ICCTI (Portugal). A. L. Amaral was supported by a PhD grant (PRAXIS XXI/BD/20325/99) of ‘Fundação para a Ciência e Tecnologia’ (Portugal). M. da Motta was supported by a grant of the National Council of Scientific and Technological Development of Brazil (CNPq)

Study on the Performance of Wastewater Treatment Plant by Image Analysis: Validation and Case Study

Um método baseado na análise de imagens foi desenvolvido para caracterizar os flocos de lodo ativado em termos do seu tamanho e forma (dimensão fractal) e da abundância de bactérias filamentosas. Após ter sido testado em experimentos em escala piloto, o método foi validado para estações de tratamento reais. Foram analisadas doze estações de tratamento de esgotos situadas na França e em Portugal, de tamanhos e processos diferentes. Em seguida realizou-se um acompanhamento sobre a estação de Braga (Portugal) que estava com problemas de intumescimento do lodos (“bulking” filamentoso).Automated methods based on image analysis have been developed to characterise activated sludge in terms of size and shape (fractal dimension) of flocs and abundance of filamentous bacteria. After tests on pilot-scale reactors, the method has been validated on samples from twelve different full-scale wastewater treatment plants of different sizes and processes in France and Portugal. Finally sludge morphology changes have been monitored during a bulking event on a full-scale plant in Portugal

Les nouveaux patrimoines en Pays de la Loire

Richement illustré et doté de nombreuses cartes inédites, cet ouvrage interroge la signification de l’importance croissante des « nouveaux patrimoines ». Contribuant à promouvoir le respect de la diversité culturelle et la promotion de la créativité humaine, ils présentent aussi un versant économique non négligeable. Ce livre, centré sur les Pays de la Loire, rassemble une cinquantaine de contributeurs, universitaires et professionnels du patrimoine, du tourisme et de la médiation culturelle

Study of protozoa population in wastewater treatment plants by image analysis

Protozoa are important micro-organisms taking part to the ecosystem balance in wastewater treatment plants. A procedure for their semi-automated identification and counting based on image analysis is proposed. The main difficulty is the segmentation of the protozoa as most of them are in contact with the sludge. The protozoa are characterized by the size of their silhouette (area and length) and three shape factors (elongation, circularity and eccentricity). The identification is performed after projecting the resulting 5D space into a 3D space of Principal Components. The rate of automated identification is actually higher than 50% for some of the species found commonly in activated sludge

Reconnaissance semi-automatique de la microfaune des boues activées des stations d’epuration des eaux usées : PROTOREC v 2.0

Une procédure a été développée pour la reconnaissance semi-automatique de protozoaires présents dans les boues activées. Après sélection sur l’image de la zone d’intérêt où se trouve l’individu, la taille et la forme de la silhouette de ce dernier sont caractérisées par onze paramètres. La classification selon l’espèce se fait par étape, chacune faisant appel à une procédure d’analyse factorielle discriminante. Durant la phase de validation un taux de reconnaissance supérieur à 70% a été obtenu pour la plus grande partie des espèces prises en compte.Brasil. Ministério da Ciência e Tecnologia. Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).Ambassade de France au Portugal.Ministério da Ciência e Tecnologia. Instituto de Cooperação Científica e Tecnológica Internacional (ICCTI)

Sludge characterization by image analysis

In wastewater treatment plants by activated sludge, a complex ecosystem constituted mainly of bacteria, protozoa and metazoa is degrading the pollution. Bacteria are agglomerated as flocs, exopolymers helping to bind zoogleal bacteria to filamentous bacteria which constitute the backbone of the flocs. When a good equilibrium is not maintained between these two bacterial groups, problems occur such as pin-floc (when filamentous bacteria are not present), filamentous bulking (when too many filamentous bacteria are present) or viscous bulking (when exopolymers are produced in excess). The protozoa, which contribute to a decrease of the effluent turbidity (by consumption of free bacteria and suspended matter) and stimulate the bacterial growth (by grazing on the flocs) are very sensitive to the plant operation conditions. They can be classified as amoebae, flagellates and ciliated. Generally speaking the species identification and the counting of filamentous bacteria and protozoa are performed manually, which is rather tedious and requires experts for the identification. Image-based procedures have been developed to try to solve this problem. A fully automated procedure has been tested and validated at pilot scale and full-scale: a drop of sludge is examined with an optical microscope (no fixation or staining, brightfield examination), a series of monochrome images is grabbed and analysed to provide information on the number and total length of filamentous bacteria and the size and shape of flocs. More recently this analysis has been coupled to a Gram-staining procedure to evaluate the ratio of Gram-positive to Gram-negative bacteria, as an indication of the species distribution. A semi-automated procedure has been developed in parallel for protozoa. The recognition rate is actually higher than 80% for some species. As the protozoa may be in contact with the flocs, the image segmentation is performed manually by the operator who defines a area of interest around the micro-organism. To improve the classification rate, new morphological descriptors are presently included

Characterisation of activated sludge by automated image analysis : validation on full-scale plants

Automated methods based on the analysis of macro- and meso-scale images has been developed to characterise activated sludge in terms of size and shape (fractal dimension) of flocs and abundance of filamentous bacteria. After tests on pilot-scale reactors, the method has been validated on full-scale samples from twelve different wastewater treatment plants in France and Portugal