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Mikrobiologi and Microbiology

We studied the flocculation mechanism at the molecular level by determining the atomic structures of N-Flo1p and N-Lg-Flo1p in complex with their ligands. We show that they have similar ligand binding mechanisms but distinct carbohydrate specificities and affinities, which are determined by the compactness of the binding site. We characterized the glycans of Flo1p and their role in this binding process and demonstrate that glycan-glycan interactions significantly contribute to the cell-cell adhesion mechanism. Therefore, the extended flocculation mechanism is based on the self-interaction of Flo proteins and this interaction is established in two stages, involving both glycan-glycan and protein-glycan interactions. The crucial role of calcium in both types of interaction was demonstrated: Ca-2(+) takes part in the binding of the carbohydrate to the protein, and the glycans aggregate only in the presence of Ca-2(+). These results unify the generally accepted lectin hypothesis with the historically first-proposed "Ca-2(+)-bridge" hypothesis. Additionally, a new role of cell flocculation is demonstrated; i.e., flocculation is linked to cell conjugation and mating, and survival chances consequently increase significantly by spore formation and by introduction of genetic variability. The role of Flo1p in mating was demonstrated by showing that mating efficiency is increased when cells flocculate and by differential transcriptome analysis of flocculating versus nonflocculating cells in a low-shear environment (microgravity). The results show that a multicellular clump (floc) provides a uniquely organized multicellular ultrastructure that provides a suitable microenvironment to induce and perform cell conjugation and mating. IMPORTANCE Yeast cells can form multicellular clumps under adverse growth conditions that protect cells from harsh environmental stresses. The floc formation is based on the self-interaction of Flo proteins via an N-terminal PA14 lectin domain. We have focused on the flocculation mechanism and its role. We found that carbohydrate specificity and affinity are determined by the accessibility of the binding site of the Flo proteins where the external loops in the ligand-binding domains are involved in glycan recognition specificity. We demonstrated that, in addition to the Flo lectin-glycan interaction, glycan-glycan interactions also contribute significantly to cell-cell recognition and interaction. Additionally, we show that flocculation provides a uniquely organized multicellular ultrastructure that is suitable to induce and accomplish cell mating. Therefore, flocculation is an important mechanism to enhance long-term yeast survival.

Hygiene and public health, epidemiology, occupational medicine, Hygiène et santé publique, épidémiologie, médecine du travail, Microbiology, infectious diseases, Microbiologie, maladies infectieuses, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Pathologie de l'appareil digestif, Digestive diseases, Aparato digestivo patología, Aliment, Food, Alimento, Epidémiologie, Epidemiology, Epidemiología, Homme, Human, Hombre, Intoxication alimentaire, Food poisoning, Intoxicación alimentaria, Microbiologie, Microbiology, and Microbiología

The Belgian data for foodborne norovirus (NoV) outbreaks became available for the first time with the introduction of an extraction and detection protocol for NoV in the National Reference Laboratory for foodborne outbreaks in September 2006. In 2007, 10 NoV foodborne outbreaks were reported affecting 392 persons in Belgium. NoV became the most detected agent in foodborne outbreaks followed by Salmonella (eight foodborne outbreaks). The major implicated foods were sandwiches (4/10), where food handlers reported a history of gastroenteritis in two outbreaks. A food handler was implicated in the limited number of Belgian NoV outbreaks which is in accord with internationally recorded data. Forty foodborne and waterborne outbreak events due to NoV, epidemiological and/or laboratory confirmed, from 2000 to 2007 revealed that in 42.5 % of the cases the food handler was responsible for the outbreak, followed by water (27·5%), bivalve shellfish (17·5%) and raspberries (10·0%).

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Plant biology and physiology, Biologie et physiologie végétales, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Métabolisme. Enzymes, Metabolism. Enzymes, Ecologie animale, vegetale et microbienne, Animal, plant and microbial ecology, Ecologie animale et végétale, Animal and plant ecology, Autoécologie, Autoecology, Végétaux et champignons, Plants and fungi, Activité enzymatique, Enzymatic activity, Actividad enzimática, Bactérie, Bacteria, Cyanobacteria, Enzyme, Enzima, Facteur milieu, Environmental factor, Factor medio, Oxidoreductases, Phytoplancton, Phytoplankton, Fitoplancton, Chlorophylle, Chlorophyll, Clorofila, Eclairement énergétique, Irradiance, Aclaramiento energético, Fixation azote, Nitrogen fixation, Fijación nitrogeno, Flottabilité, Buoyancy, Flotabilidad, Intégration numérique, Numerical integration, Integración numérica, Milieu marin, Marine environment, Medio marino, Modèle mathématique, Mathematical model, Modelo matemático, Nitrogenase, Photosynthèse, Photosynthesis, Fotosíntesis, Variation journalière, Daily variation, Variación diaria, and Aphanizomenon

Measurements were made of the rates of nitrogenase activity (acetylene reduction) by cyanobacteria collected from the Baltic Sea at 2-h intervals, over a period of 24 h, and incubated under natural light. By relating the chlorophyll-specific rate of N2 fixation (PN) to the mean photon irradiance (I) at different periods, a PN/I curve was constructed. A mathematical description of this relationship was used in the calculation of rates of N2 fixation at different depths and times of day from continuous measurements of surface irradiance and light attenuation. By relating these calculations to the vertical distribution of chlorophyll due to Aphanizomenon flos-aquae, an estimate of the daily integral of N2 fixation by the population of this cyanobacterium was obtained: it varied from 039 to 071 mmol m-2 with a mean value of 053 mmol m-2 over 9 d. Comparisons with similar calculations of the daily integral of photosynthesis over the same period indicated the atomic ratio of N/C fixed is about 022, not very different from the N/C ratio expected for the elemental composition of these cyanobacteria. It is demonstrated that when buoyant gas-vacuolate colonies float up during calm periods the increased irradiance that they experience supports an increased rate of N2 fixation. This increase is less than that seen for carbon fixation because photosynthesis is negated by respiration at low irradiances and is less inhibited at high irradiances.

Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, Microbiology, infectious diseases, Microbiologie, maladies infectieuses, Virology, Virologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Virologie, Virology, Cycle de développement, interférence, relations hôte-virus, pouvoir pathogène, souches diverses, Replicative cycle, interference, host-virus relations, pathogenicity, miscellaneous strains, Betaherpesvirinae, Cytokine, Citoquina, Herpesviridae, Infection, Infección, Mammalia, Rodentia, Vertebrata, Virus, Activité biologique, Biological activity, Actividad biológica, Cytomegalovirus, In vitro, In vivo, Interféron gamma, Gamma interferon, Interferón gamma, Modèle animal, Animal model, Modelo animal, Multiplication virus, Virus multiplication, Multiplicación virus, Pathologie expérimentale, Experimental disease, Patología experimental, Rat, Rata, Relation hôte virus, Host virus relation, Relación huesped virus, Virose, Viral disease, and Virosis

The role of gamma interferon (IFN-γ) in the resolution of rat cytomegalovirus (RCMV) infection was investigated. In the spleen, IFN-γ-producing cells reached maximum numbers on day 7 after infection. Prophylactic treatment with high doses of recombinant rat IFN-γ exerted antiviral activity in fibroblasts and protected immunosuppressed rats against a lethal RCMV challenge. Remarkably, in immunocompetent rats, neutralization of endogenous IFN-γ activity significantly reduced the numbers of RCMV antigen-expressing cells in the spleen, the predominant site of viral replication. Moreover, protection of radiation-immunosuppressed infected rats by transferred immune T cells was enhanced by coinjection of IFN-γ neutralizing antibodies.

Plant biology and physiology, Biologie et physiologie végétales, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Métabolisme. Enzymes, Metabolism. Enzymes, Bactérie, Bacteria, Cyanobacteria, Enzyme, Enzima, Activité enzymatique, Enzymatic activity, Actividad enzimática, Inactivation, Inactivación, Localisation, Localization, Localización, Modification, Modificación, Méthode immunoblotting, Immunoblotting assay, Nitrogenase, Technique immunoor, Immunogold labelling, Técnica inmunooro, Variation diurne, Diurnal variation, Variación diurna, Dinitrogénase réductase, Dinitrogénase, and Oscillatoria limosa

Biotechnology, Biotechnologies, Microbiology, infectious diseases, Microbiologie, maladies infectieuses, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Métabolisme. Enzymes, Metabolism. Enzymes, Bacteria, Bactérie, Acétate, Acetate, Acetato, Anaérobiose, Anaerobiosis, Cyanobacteria, Diholoside, Disaccharide, Diholosido, Ethanol, Etanol, Fermentation, Fermentación, Glycogène, Glycogen, Glicógeno, Lactate, Lactates, Lactato, Métabolisme, Metabolism, Metabolismo, Obscurité, Obscurity, Oscuridad, Sulfure, Sulfides, Sulfuro, Tréhalose, Trehalose, Trehalosa, Fermentation hétérolactique, and Oscillatoria limosa

The marine nitrogen-fixing cyanobacterium Oscillatoria limosa, strain 23 (Oldenburg) was investigated with respect to its dark anaerobic metabolism. As soon as the cells were incubated anaerobically in the dark, they started to ferment. Glycogen was presumably degraded via the heterolactic fermentative pathway. Glycogen-glucose was degraded to equimolar amounts of lactate, ethanol and carbon dioxide. The disaccharide trehalose, which serves as an osmoprotectant in O. limosa, was also catabolized.

Biotechnology, Biotechnologies, Microbiology, infectious diseases, Microbiologie, maladies infectieuses, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Métabolisme. Enzymes, Metabolism. Enzymes, Bacteria, Cyanobacteria, Bactérie, Azote, Nitrogen, Nitrogeno, Aérobiose, Aerobiosis, Enzyme, Enzima, Fixation azote, Nitrogen fixation, Fijación nitrogeno, Lumière, Light, Luz, Métabolisme, Metabolism, Metabolismo, Nitrogenase, Obscurité, Obscurity, Oscuridad, Oscillatoria, Photosynthèse, Photosynthesis, Fotosíntesis, Respiration cellulaire, Cell respiration, and Respiración celular

Biotechnology, Biotechnologies, Microbiology, infectious diseases, Microbiologie, maladies infectieuses, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Métabolisme. Enzymes, Metabolism. Enzymes, Biotechnologie, Biotechnology, Recherche fondamentale orientée, Mission oriented research, Biologie des microorganismes d'intérêt industriel confirmé ou potentiel, Biology of microorganisms of confirmed or potential industrial interest, Physiologie et métabolisme, Physiology and metabolism, Bacteria, Oscillatoriaceae, Oscillatoriales, Bactérie, Culture microorganisme, Microorganism culture, Cultivo microorganismo, Cyanobacteria, Enzyme, Enzima, Fixation azote, Nitrogen fixation, Fijacion nitrogenada, Nitrogenase, Oscillatoria, Oxidoreductase, Oxidorreductasa, Oxygène, Oxygen, Protection, Proteccion, Toxicité, Toxicity, and Toxicidad

Biotechnology, Biotechnologies, Microbiology, infectious diseases, Microbiologie, maladies infectieuses, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Métabolisme. Enzymes, Metabolism. Enzymes, Biotechnologie, Biotechnology, Recherche fondamentale orientée, Mission oriented research, Biologie des microorganismes d'intérêt industriel confirmé ou potentiel, Biology of microorganisms of confirmed or potential industrial interest, Physiologie et métabolisme, Physiology and metabolism, Bacteria, Oscillatoriaceae, Oscillatoriales, Bactérie, Alternance, Alternancia, Culture microorganisme, Microorganism culture, Cultivo microorganismo, Cyanobacteria, Dosage, Assay, Dosificacion, Enzyme, Enzima, Fixation azote, Nitrogen fixation, Fijacion nitrogenada, Lumière, Light, Luz, Nitrogenase, Obscurité, Obscurity, Oscuridad, Oscillatoria, Oxidoreductase, and Oxidorreductasa

Medical laboratory techniques, Techniques de laboratoire médical, Microbiology, infectious diseases, Microbiologie, maladies infectieuses, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Microbiologie, Microbiology, Bactériologie, Bacteriology, Méthodes bactériologiques et techniques utilisées en bactériologie, Bacteriological methods and techniques used in bacteriology, Bactériochlorophylle, Bacteriochlorophyll, Bactériophéophytine, Bacteriopheophytine, Chlorophylle, Chlorophyll, Communauté microbienne, Communauté, Community, Dosage, Assay, Ecologie, Ecology, Ecosystème, Ecosystem, Environnement, Environment, Microflore, Microflora, Microorganisme, Microorganism, Méthode, Method, Pigment photosynthétique, Photosynthetic pigment, Pigment, Pigments, Simultané, Concurrent, Soufre, and Sulfur

Asopinae, criação massal, classes de peso, Biology (General), QH301-705.5, Microbiology, and QR1-502

O potencial reprodutivo de fêmeas de Supputius cincticeps (Stal) (Heteroptera: Pentatomidae) de duas classes de peso foi avaliado. Machos e fêmeas desse predador foram obtidos de ninfas alimentadas com pupas de Tenebrio molitor L. (Coleoptera: Tenebrionidae). Foram analisadas fêmeas com peso inferior a 45 mg (fêmeas leves) e superior a 60 mg (fêmeas pesadas). A longevidade e os períodos de pré-oviposição, oviposição e pós-oviposição foram semelhantes entre fêmeas das duas classes de peso, enquanto aquelas mais pesadas apresentaram maior número de posturas, ovos, ovos/postura e ninfas. Períodos entre posturas e de incubação dos ovos foram menores para fêmeas com peso superior a 60mg. Esses resultados são discutidos em relação ao uso de fêmeas mais pesadas de S. cincticeps para aumentar a produção em criação massal desse predadorThe reproductive potential of Supputius cincticeps (Stal) (Heteroptera: Pentatomidae) females of two weight classes was evaluated with males and females of this predator obtained from nymphs fed on Tenebrio molitor L. (Coleoptera: Tenebrionidae) pupae. Females of S. cincticeps weighing less than 45 mg (light females) and more than 60 mg (heavy females) constituted the treatments. Pre-oviposition, oviposition and post-oviposition periods besides adult longevity were similar between treatments while number of egg masses, eggs, eggs/egg mass and number of nymphs hatched were higher for heavier females. Periods between egg mass laying and egg incubation were shorter for insects of the last treatment. These results are discussed in relation to the use of heavier females of S. cincticeps to improve mass rearing of this predator in laboratory

NITROGEN fixation, CYANOBACTERIA, MARINE biology, and MICROBIOLOGY