Numération bactérienne en épifluorescence par la méthode couplée DAPI-INT : application à un cas concret

Un protocole simple de coloration par la méthode couplée DAPI-INT en microscopie à épifluorescence, associé à une lecture des préparations par caméra et vidéo-Imprimante, permet la mesure de paramètres biologiques impliqués directement dans les processus de dégradation de la matière organique en rivière : numérations de microflore totale, nombre de cellules physiologiquement actives (réduisant l'INT), nombre de cellules avec réserves de PHB, dimensions cellulaires et répartition en classes de taille aboutissant à l'évaluation de la biomasse carbonée.Tous les comptages et mesures sont réalisés à partir de clichés d'imprimante thermique, ce qui assure une reproductibilité et une comparaison entre échantillons plus objective qu'à partir de seules observations directes.Cette méthode permet de différer soit les comptages (échantillons fixés au formol après incubation à l'INT), soit surtout les mesures de dimensions cellulaires (archivage des clichés pour une exploitation ultérieure).Son application au cas de la rivière Charente montre une évolution particulière de la biomasse bactérienne en aval des rejets de l'agglomération d'Angoulême. La mise en évidence de cellules de grande taille (biovolume moyen de 0,3 µm3) et d'une population plus active pourrait traduire une modification physiologique de micro-organismes autochtones réagissant à des conditions de milieu particulières (rejets d'effluents carencés en azote).The increasing appreciation of heterotrophic bacterioplankton as an important and dynamic compartment in the carbon cycle of aquatic ecosystems has led to the development of methods allowing reproducible and reliable direct bacterial counts. Thus, since the 1970's, enumeration of bacteria by epifluorescence microscopy has become a widely used method for the estimation of cell number and biovolume. Cell counts are made using either the acridine orange (Hobbie et al. 1977) or the DAPI (Porter 1980) procedure on fixed samples. A tracer of cellular respiratory activity (INT) can be linked to either of these two methods before the samples are killed by formalin. Two observations of the same field, one in transmitted light, the other by epifluorescence, allow a determination of the percentage of active bacterioplankton (Tabor and Neihof 1982, Dufour 1990).However, the various authors working with these procedures have modified the protocol and up to now there has not been a standard method. Thus, before using it for the first time, numerous verifications about filters, concentration of dye solution and methods for estimating cell volume are necessary.In this study a simultaneous comparison, between three brands of filters, two dye solutions and three methods for numeration and cell volume estimation (by direct count, by photographs and by video graphic printer) has been performed.All the tests have been clone with samples collected from rivera or lakes. In comparison to laboratory cultures, natural bacteria are observed with difficulty on account of their small size and especially because natural organic matter absorbs dye solution and so interferes with counts. We prefer to use DAPI rather than acridine orange, because DAPI is colorless in direct light, so it doesn't interfere with enumeration of respiring bacteria (red crystal inside cell). To obtain the best contrast for observation in epifluorescence microscopy, a very fast drying in the open air and a structure less troublesome for the observation in direct light, we have chosen Millipore black filters. A camera associated with a video printer gives better results compared to the photographs : no fluorescent "halo" around the tell image and no waste of time waiting for development of the film. All counts and measures were made from video graphic printer photographs, which assures reproductibility and more objective comparisons between samples, compared to direct counts (with eyes) that are tiring and subjective. Finally, we can defer counting (samples fixed in formol after INT incubation) or cell size measurements (analysis of recorded photos) to a later time.On the basis of this tests, the DAPI-INT method in fluorescence microscopy, associated with the reading of slides with a camera and a video-printer, allows one to measure biological parameters directly implicated in the degradation of river organic matter : abundance of total microflora, number of physiologically active cells (reducing INT) and cells with PHB reserves, cell sizes and size range distribution used to evaluate carbon biomass.The application of this method to the river Charente (April to November 1991) shows a particular fate of bacterial biomass downstream from the city of Angouleme. A multifactor analysis of variance with a multiple range analyses (Tukey) shows that bacterial cells collected downstream from the effluent discharge of the Angouleme wastewater treatment plant are the largest (average cell volume up to 0.3 µm3) and the more active cells. Similar trends have also been observed by Servais and Garnier (1989) downstream from the Paris wastewater treatment plant (Achères) on the Seine river. These authors suggested that allochtonous populations associated with the urban sewage were different from the autochtonous populations (higher biovolume). To verify this hypothesis, a sampling campaign (June 92) was performed on five stations along an eight kilometers river reach. There weren't large size bacteria downstream from the effluent discharge of Frégeneuil, Fléac and St Michel wastewater treatment plants. We Pound the largest bacteria at Nersac. Thus it seems that these large bacteria don't came from wastewater treatment plant. The increase of autochtonous bacterial size could be interpretated as a nutritional stress, the increase of the C/N ratio preventing cellular division (nitrogen deficient sewages)

Digital archives, e-books and narrative space

In this paper we are concerned with the capacity of digital media to enable publics to tell their own environmental stories using digital broadcast archives (DBAs). We consider how digital media afford different ways of telling stories in relation to digital media archives. Central to this discussion is our experience of writing e‐books as part of the AHRC‐funded project “Earth in Vision: BBC coverage of environmental change 1960–2010”. The e‐book format has been adopted in order to explore some of the possibilities for writing environmental history and politics using DBAs

Identification of Novel Functional Inhibitors of Acid Sphingomyelinase

We describe a hitherto unknown feature for 27 small drug-like molecules, namely functional inhibition of acid sphingomyelinase (ASM). These entities named FIASMAs (Functional Inhibitors of Acid SphingoMyelinAse), therefore, can be potentially used to treat diseases associated with enhanced activity of ASM, such as Alzheimer's disease, major depression, radiation- and chemotherapy-induced apoptosis and endotoxic shock syndrome. Residual activity of ASM measured in the presence of 10 µM drug concentration shows a bimodal distribution; thus the tested drugs can be classified into two groups with lower and higher inhibitory activity. All FIASMAs share distinct physicochemical properties in showing lipophilic and weakly basic properties. Hierarchical clustering of Tanimoto coefficients revealed that FIASMAs occur among drugs of various chemical scaffolds. Moreover, FIASMAs more frequently violate Lipinski's Rule-of-Five than compounds without effect on ASM. Inhibition of ASM appears to be associated with good permeability across the blood-brain barrier. In the present investigation, we developed a novel structure-property-activity relationship by using a random forest-based binary classification learner. Virtual screening revealed that only six out of 768 (0.78%) compounds of natural products functionally inhibit ASM, whereas this inhibitory activity occurs in 135 out of 2028 (6.66%) drugs licensed for medical use in humans

Germline variation at 8q24 and prostate cancer risk in men of European ancestry

Chromosome 8q24 is a susceptibility locus for multiple cancers, including prostate cancer. Here we combine genetic data across the 8q24 susceptibility region from 71,535 prostate cancer cases and 52,935 controls of European ancestry to define the overall contribution of germline variation at 8q24 to prostate cancer risk. We identify 12 independent risk signals for prostate cancer (p < 4.28 × 10−15), including three risk variants that have yet to be reported. From a polygenic risk score (PRS) model, derived to assess the cumulative effect of risk variants at 8q24, men in the top 1% of the PRS have a 4-fold (95%CI = 3.62–4.40) greater risk compared to the population average. These 12 variants account for ~25% of what can be currently explained of the familial risk of prostate cancer by known genetic risk factors. These findings highlight the overwhelming contribution of germline variation at 8q24 on prostate cancer risk which has implications for population risk stratification

Les types d'Agrias de la collection de Mme G. Fournier de Horrack [Lep. Nymphalidae]

Rebillard P., Viette Pierre. Les types d'Agrias de la collection de Mme G. Fournier de Horrack [Lep. Nymphalidae]. In: Bulletin de la Société entomologique de France, volume 65 (3-4), Mars-avril 1960. pp. 109-117

Pierre Batcheff and stardom in 1920s French cinema

This book is the first major study of a French silent cinema star. It focuses on Pierre Batcheff, a prominent popular cinema star in the 1920s, the French Valentino, best-known to modern audiences for his role as the protagonist of the avant-garde film classic Un chien andalou. Unlike other stars, he was linked to intellectual circles, especially the Surrealists. The book places Batcheff in the context of 1920s popular cinema, with specific reference to male stars of the period. It analyses the tensions he exemplifies between the ‘popular’ and the ‘intellectual’ during the 1920s, as cinema - the subject of intense intellectual interest across Europe - was racked between commercialism and ‘art’. A number of the major films are studied in detail: Le Double amour (Epstein, 1925), Feu Mathias Pascal (L’Herbier, 1925), Éducation de prince (Diamant-Berger, 1927), Le Joueur d’échecs (Bernard, 1927), La Sirène des tropiques (Etiévant and Nalpas, 1927), Les Deux timides (Clair, 1928), Un chien andalou (Buñuel, 1929), Monte-Cristo (Fescourt, 1929), and Baroud (Ingram, 1932). Highlights include: The first major study of a French silent cinema star. Provides an in-depth analysis of star performance. Includes extensive appendices of documents from popular cinema magazines of the period. Phil Powrie is Professor of Cinema Studies at the University of Sheffield. Éric Rebillard is a member of the Association Française de Recherche sur l’Histoire du Cinéma

Pierre Batcheff and stardom in 1920s French cinema

This book is the first major study of a French silent cinema star. It focuses on Pierre Batcheff, a prominent popular cinema star in the 1920s, the French Valentino, best-known to modern audiences for his role as the protagonist of the avant-garde film classic Un chien andalou. Unlike other stars, he was linked to intellectual circles, especially the Surrealists. The book places Batcheff in the context of 1920s popular cinema, with specific reference to male stars of the period. It analyses the tensions he exemplifies between the ‘popular’ and the ‘intellectual’ during the 1920s, as cinema - the subject of intense intellectual interest across Europe - was racked between commercialism and ‘art’. A number of the major films are studied in detail: Le Double amour (Epstein, 1925), Feu Mathias Pascal (L’Herbier, 1925), Éducation de prince (Diamant-Berger, 1927), Le Joueur d’échecs (Bernard, 1927), La Sirène des tropiques (Etiévant and Nalpas, 1927), Les Deux timides (Clair, 1928), Un chien andalou (Buñuel, 1929), Monte-Cristo (Fescourt, 1929), and Baroud (Ingram, 1932). Highlights include: The first major study of a French silent cinema star. Provides an in-depth analysis of star performance. Includes extensive appendices of documents from popular cinema magazines of the period. Phil Powrie is Professor of Cinema Studies at the University of Sheffield. Éric Rebillard is a member of the Association Française de Recherche sur l’Histoire du Cinéma

Les types d'Agrias de la collection de Mme G. Fournier de Horrack [Lep. Nymphalidae]

Rebillard P., Viette Pierre. Les types d'Agrias de la collection de Mme G. Fournier de Horrack [Lep. Nymphalidae]. In: Bulletin de la Société entomologique de France, volume 65 (3-4), Mars-avril 1960. pp. 109-117