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1. An antimicrobial peptide-resistant minor subpopulation of Photorhabdus luminescens is responsible for virulence

Author

Emeric Dubois, Sylvie Pagès, Anne Lanois, Julien Brillard, Maurine Bonabaud, Annabelle Mouammine, Sophie Gaudriault, Alain Givaudan, David Roche, Grégory Jubelin, Ludovic Legrand, Stéphane Cruveiller, Diversité, Génomes & Interactions Microorganismes - Insectes [Montpellier] ( DGIMI ), Institut National de la Recherche Agronomique ( INRA ) -Université Montpellier 2 - Sciences et Techniques ( UM2 ) -Université de Montpellier ( UM ), Microbiologie Environnement Digestif Santé - Clermont Auvergne ( MEDIS ), Université Clermont Auvergne ( UCA ) -INRA Clermont-Ferrand-Theix, GenomiX, Institut de Génomique Fonctionnelle, Génomique métabolique ( UMR 8030 ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université d'Évry-Val-d'Essonne ( UEVE ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Institut de Génomique Fonctionnelle ( IGF ), Centre National de la Recherche Scientifique ( CNRS ) -Université Montpellier 2 - Sciences et Techniques ( UM2 ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Université Montpellier 1 ( UM1 ) -Université de Montpellier ( UM ), Centre Interlangues - Texte, Image, Langage ( TIL ), Université de Bourgogne ( UB ), Interactions plantes-microorganismes et santé végétale, Institut National de la Recherche Agronomique ( INRA ) -Université Nice Sophia Antipolis ( UNS ), Université Côte d'Azur ( UCA ) -Université Côte d'Azur ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), Sécurité et Qualité des Produits d'Origine Végétale ( SQPOV ), Institut National de la Recherche Agronomique ( INRA ) -Université d'Avignon et des Pays de Vaucluse ( UAPV ), Ecologie microbienne des insectes et interactions hôte-pathogène ( EMIP ), Institut National de la Recherche Agronomique ( INRA ) -Université Montpellier 2 - Sciences et Techniques ( UM2 ), Diversité, Génomes & Interactions Microorganismes - Insectes [Montpellier] (DGIMI), Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM), Microbiologie Environnement Digestif Santé - Clermont Auvergne (MEDIS), INRA Clermont-Ferrand-Theix-Université Clermont Auvergne (UCA), Institut de Génomique Fonctionnelle - Montpellier GenomiX (IGF MGX), Institut de Génomique Fonctionnelle (IGF), Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS), Analyse Bio-Informatique pour la Génomique et le Métabolisme (LABGeM), Génomique métabolique (UMR 8030), Genoscope - Centre national de séquençage [Evry] (GENOSCOPE), Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS)-Genoscope - Centre national de séquençage [Evry] (GENOSCOPE), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), Laboratoire des interactions plantes micro-organismes (LIPM), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), INRA 2011_1333_03 2015_1333, Microbiologie Environnement Digestif Santé (MEDIS), Institut National de la Recherche Agronomique (INRA)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020]), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-BioCampus (BCM), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA)-Centre National de la Recherche Scientifique (CNRS), Université Clermont Auvergne (UCA)-INRA Clermont-Ferrand-Theix, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université d'Évry-Val-d'Essonne (UEVE)-Genoscope - Centre national de séquençage [Evry] (GENOSCOPE), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université d'Évry-Val-d'Essonne (UEVE), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université d'Évry-Val-d'Essonne (UEVE)-Genoscope - Centre national de séquençage [Evry] (GENOSCOPE), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université d'Évry-Val-d'Essonne (UEVE), INRA Clermont-Ferrand-Theix-Université Clermont Auvergne [2017-2020] (UCA [2017-2020]), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS)-Genoscope - Centre national de séquençage [Evry] (GENOSCOPE), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Université d'Évry-Val-d'Essonne (UEVE)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0301 basic medicine, Insecta, Operon, [SDV]Life Sciences [q-bio], [ SDV.AEN ] Life Sciences [q-bio]/Food and Nutrition, 030106 microbiology, Population, salmonella, Virulence, Drug resistance, [ SDV.MP.BAC ] Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, peptide antimicrobien, Article, Bacterial genetics, Microbiology, 03 medical and health sciences, inhomogeneity, Disk Diffusion Antimicrobial Tests, Photorhabdus luminescens, Drug Resistance, Bacterial, Gene Order, hétérogénéité, Animals, education, ComputingMilieux_MISCELLANEOUS, photorhabdus luminescens, bactérie, education.field_of_study, Multidisciplinary, biology, Gene Expression Profiling, Enterobacteriaceae Infections, biology.organism_classification, bacterium, 030104 developmental biology, Regulon, Gene Expression Regulation, Genes, Bacterial, Mutation, Photorhabdus, Antimicrobial Cationic Peptides
Abstract

Some of the bacterial cells in isogenic populations behave differently from others. We describe here how a new type of phenotypic heterogeneity relating to resistance to cationic antimicrobial peptides (CAMPs) is determinant for the pathogenic infection process of the entomopathogenic bacterium Photorhabdus luminescens. We demonstrate that the resistant subpopulation, which accounts for only 0.5% of the wild-type population, causes septicemia in insects. Bacterial heterogeneity is driven by the PhoPQ two-component regulatory system and expression of pbgPE, an operon encoding proteins involved in lipopolysaccharide (LPS) modifications. We also report the characterization of a core regulon controlled by the DNA-binding PhoP protein, which governs virulence in P. luminescens. Comparative RNAseq analysis revealed an upregulation of marker genes for resistance, virulence and bacterial antagonism in the pre-existing resistant subpopulation, suggesting a greater ability to infect insect prey and to survive in cadavers. Finally, we suggest that the infection process of P. luminescens is based on a bet-hedging strategy to cope with the diverse environmental conditions experienced during the lifecycle.

Published
2017
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2. Effect of a toxicant on phagocytosis pathways in the freshwater snail Lymnaea stagnalis

Author

Michel Brehélin, Luc Madec, Jacqueline Russo, Ecosystèmes, biodiversité, évolution [Rennes] (ECOBIO), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Ecologie microbienne des insectes et interactions hôte-pathogène (EMIP), Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2), Université de Rennes (UR)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Hemocytes, Time Factors, Histology, Cell Survival, Phalloidine, Gastropoda, Pulmonata), Lipopolysaccharide, Lymnaea stagnalis, [SDV.TOX.TCA]Life Sciences [q-bio]/Toxicology/Toxicology and food chain, Freshwater snail, Pathology and Forensic Medicine, 03 medical and health sciences, chemistry.chemical_compound, Phagocytosis, Lectins, [SDV.BC.IC]Life Sciences [q-bio]/Cellular Biology/Cell Behavior [q-bio.CB], Animals, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Cytoskeleton, Actin, Fluorescent Dyes, Lymnaea, 030304 developmental biology, Lymnaea stagnalis (Mollusca, 0303 health sciences, Dose-Response Relationship, Drug, biology, Herbicides, Rhodamines, 030302 biochemistry & molecular biology, Immunity, Haemocyte, Cell Biology, Anatomy, biology.organism_classification, Actin cytoskeleton, Actins, Wheat germ agglutinin, Cell biology, chemistry, Concanavalin A, Benzamides, biology.protein, Fluorescein-5-isothiocyanate, Water Pollutants, Chemical, Toxicant
Abstract

International audience; The disturbance of plasma membrane carbohydrates and of lipopolysaccharide (LPS) ligands in relation to cytoskeletal transformations of haemocytes has been investigated after chronic exposure of pond snails (Lymnaea stagnalis) to the peroxidizing toxicant fomesafen. Neither of the two lectins used (concanavalin A and wheat germ agglutinin) showed any binding modification after incubation of the snails in the presence of the toxicant. However, after exposure of the snails to fomesafen, a clear and persistent reduction in LPS labelling of haemocytes occurred. The actin cytoskeleton of the same cells also appeared to be sensitive to the toxicant. The reduction in LPS-binding sites was related to actin staining, leading to the hypothesis that LPS ligands and actin could be similarly modulated by the toxicant. Damaged cells showed non-adherent membrane portions with reduced filopodial extrusions, exhibiting a smooth surface free of microvilli. These changes could lower the spreading and adhesion of the cells and could therefore account for the loss in their phagocytic capabilities.

Published
2008
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3. X-tox: An atypical defensin derived family of immune-related proteins specific to Lepidoptera

Author

Michel Brehélin, Jean-Michel Escoubas, Christopher W. Wheat, Yvan Boublik, François Cousserans, Pierre-Alain Girard, Anne-Nathalie Volkoff, Ecologie microbienne des insectes et interactions hôte-pathogène (EMIP), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de la Recherche Agronomique (INRA), Centre National de la Recherche Scientifique (CNRS), University of Helsinki, Biology Department, and Biologie Intégrative et Virologie des Insectes [Univ. de Montpellier II] (BIVI)

Subjects
DEFENSIN-DERIVED, animal structures, Protein family, Molecular Sequence Data, Immunology, Antimicrobial peptides, Sf9, Spodoptera, Cell Line, Defensins, Lepidoptera genitalia, 03 medical and health sciences, fluids and secretions, 0302 clinical medicine, Tandem repeat, Animals, Amino Acid Sequence, Defensin, 030304 developmental biology, Genetics, 0303 health sciences, biology, fungi, biology.organism_classification, Virology, LEPIDOPTERA, Recombinant Proteins, Beta defensin, Tandem Repeat Sequences, [SDV.IMM]Life Sciences [q-bio]/Immunology, Insect Proteins, bacteria, INSECT IMMUNITY, IMMUNE-RELATED PROTEIN, HEMOCYTE, 030217 neurology & neurosurgery, Developmental Biology
Abstract

We report here the isolation in Spodoptera frugiperda (Lepidoptera) of an immune-related protein (hereafter named Spod-11-tox), characterized by imperfectly conserved tandem repeats of 11 cysteine-stabitized alpha beta motifs (CS-alpha beta), the structural scaffold characteristic of invertebrate defensins and scorpion toxins. Spod-11-tox orthologs were only found in Lepidopteran species, suggesting that this new protein family (named X-tox) is specific to this insect order. Moreover, phylogenetic analysis suggests that X-tox proteins represent a new class of proteins restricted to Lepidoptera and likely derived from Lepidopteran defensins. In S. frugiperda, analysis of gene expression revealed that spod-11-tox is rapidly induced by infection. However, and conversely to what is known for most insect antimicrobial peptides (AMP), spod-11-tox is mainly expressed in blood cells. Moreover, recombinant Spod-11-tox produced in the Sf9 cell line does not show any antimicrobial activity. Altogether, these results suggest that although X-tox proteins are derived from defensins, they may play a different and stilt unknown rote in Lepidoptera immune response

Published
2008
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4. The HcaR regulatory protein of Photorhabdus luminescens affects the production of proteins involved in oxidative stress and toxemia

Author

Sylvie Pagès, Sabina Chalabaev, Emma Brito-Fravallo, Antoine Danchin, Francis Biville, Evelyne Turlin, Jean-François Charles, Alain Givaudan, Abdelkader Namane, Institut Pasteur [Paris], Ecologie microbienne des insectes et interactions hôte-pathogène (EMIP), and Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2)

Subjects
Paraquat, BACTEREMIA, Bacterial Toxins, Mutant, Virulence, Spodoptera, medicine.disease_cause, Biochemistry, Microbiology, 03 medical and health sciences, Bacterial Proteins, Photorhabdus luminescens, PHOTORHABDUS LUMINESCENS, Gene expression, medicine, Animals, Electrophoresis, Gel, Two-Dimensional, [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology, OXIDATIVE STRESS, Molecular Biology, 030304 developmental biology, Regulation of gene expression, 0303 health sciences, biology, 030306 microbiology, Toxin, fungi, Gene Expression Regulation, Bacterial, Hydrogen Peroxide, Bombyx, Catalase, biology.organism_classification, TOXEMIA, Larva, Mutation, VIRULENCE, Photorhabdus, Oxidative stress
Abstract

International audience; Comparison of the proteomes of wild-type Photorhabdus luminescens and its hcaR derivative, grown in insect hemolymph, showed that hcaR disruption decreased the production of toxins (tcdA1, mcf and pirAB) and proteins involved in oxidative stress response (SodA, AhpC, Gor). The disruption of hcaR did not affect growth rate in insects, but did delay the virulence of P. luminescens in Bombyx mori and Spodoptera littoralis larvae. This delayed virulence was associated with a lower toxemia rather than delay in bacteremia. The disruption of hcaR also increased bacterial sensitivity to hydrogen peroxide. A sodA mutant and an hcaR mutant had similar phenotypes in terms of sensitivity to hydrogen peroxide, virulence, toxin gene expression, and growth rate in insects. Thus, the two processes affected by hcaR disruption - toxemia and oxidative stress response - appear to be related. Besides, expression of toxin genes tcdA1, mcf, and pirAB was decreased by paraquat challenge. We provide here the first demonstration of the importance of toxemia for P. luminescens virulence. Our results also highlight the power of proteomic analysis for detecting unexpected links between different, concomitant processes in bacteria

Published
2007
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5. Xenorhabdus nematophila (Enterobacteriacea) Secretes a Cation-selective Calcium-independent Porin Which Causes Vacuolation of the Rough Endoplasmic Reticulum and Cell Lysis

Author

Carlos Ribeiro, Michel Vignes, Michel Brehélin, Bruitparif, Institut des Biomolécules Max Mousseron [Pôle Chimie Balard] (IBMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Plasticité cérébrale (PC), Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS), Ecologie microbienne des insectes et interactions hôte-pathogène (EMIP), Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)

Subjects
0106 biological sciences, Hemocytes, Lysis, MESH: Xenorhabdus, Endoplasmic Reticulum, medicine.disease_cause, 01 natural sciences, Biochemistry, Xenorhabdus, Cytosol, MESH: Cytosol, Photorhabdus luminescens, MESH: Animals, Cells, Cultured, 0303 health sciences, Cultured, MESH: Spodoptera, medicine.anatomical_structure, MESH: Cell Survival, MESH: Calcium, Porin, [SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], Endoplasmic Reticulum, Rough, MESH: Cells, Cultured, medicine.drug, Programmed cell death, Cell Survival, Cells, MESH: Endoplasmic Reticulum, Rough, Bacterial Toxins, Porins, Spodoptera, Biology, MESH: Vacuoles, 03 medical and health sciences, Rough, medicine, Animals, Calcium, Vacuoles, Molecular Biology, 030304 developmental biology, MESH: Porins, Toxin, Endoplasmic reticulum, fungi, Neurosciences, MESH: Hemocytes, Potassium channel blocker, Cell Biology, biology.organism_classification, 010602 entomology, Red blood cell, MESH: Bacterial Toxins, Neurons and Cognition
Abstract

International audience; Xenorhabdus nematophila and Photorhabdus luminescens are two related enterobacteriaceae studied for their use in biological control and for synthesis of original virulence factors and new kinds of antibiotics. X. nematophila broth growth exhibits different cytotoxic activities on insect (Spodoptera littoralis, lepidoptera) immunocytes (hemocytes). Here we report the purification of the flhDC-dependent cytotoxin, a 10,790-Da peptide we have called alpha-Xenorhabdolysin (alpha X). We show that plasma membrane of insect hemocytes and of mammal red blood cells is the first target of this toxin. Electrophysiological and pharmacological approaches indicate that the initial effect of alpha X on macrophage plasma membrane is an increase of monovalent cation permeability, sensitive to potassium channel blockers. As a consequence, several events can occur intracellularly, such as selective vacuolation of the endoplasmic reticulum, cell swelling, and cell death by colloid-osmotic lysis. These effects, inhibited by potassium channel blockers, are totally independent of Ca(2+). However, the size of the pores created by alpha X on macrophage or red blood cell plasma membrane increases with toxin concentration, which leads to a rapid cell lysis.

Published
2003
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6. Pleiotropic role of quorum-sensing autoinducer 2 in Photorhabdus luminescens

Author

Evelyne Turlin, Nesrine Chakroun, Céline Lacroix, Sylviane Derzelle, Antoine Danchin, Lionel Frangeul, Marie-Françoise Hullo, Isabelle Bonne, Laetitia Marisa, Jean-Claude Rousselle, François Gaboriau, Evelyne Krin, Alain Givaudan, Institut Pasteur [Paris], Ecologie microbienne des insectes et interactions hôte-pathogène (EMIP), Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2), Régulations des équilibres fonctionnels du foie normal et pathologique, Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National de la Santé et de la Recherche Médicale (INSERM), Plateforme microscopie électronique, MRic Campus Santé, Rennes 1, France, ProdInra, Migration, Institut Pasteur [Paris] (IP), and Université de Rennes (UR)-Institut National de la Santé et de la Recherche Médicale (INSERM)

Subjects
Mutant, Virulence, Genetics and Molecular Biology, Applied Microbiology and Biotechnology, Microbiology, 03 medical and health sciences, chemistry.chemical_compound, Lactones, Bacterial Proteins, Photorhabdus luminescens, PHOTORHABDUS LUMINESCENS, Homoserine, Polyamines, SPODOPTERA LITTORALIS, 030304 developmental biology, PROTEOME ANALYSIS, RELATION HOTE-PARASITE, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, 0303 health sciences, Innate immune system, Ecology, biology, 030306 microbiology, Gene Expression Profiling, Biofilm, biochemical phenomena, metabolism, and nutrition, biology.organism_classification, Autoinducer-2, [SDV.EE] Life Sciences [q-bio]/Ecology, environment, Quorum sensing, Carbon-Sulfur Lyases, Oxidative Stress, chemistry, Biofilms, ESCHERICHIA COLI, Photorhabdus, Food Science, Biotechnology, BACTERIAL VIRULENCE, Signal Transduction
Abstract

Bacterial virulence is an integrative process that may involve quorum sensing. In this work, we compared by global expression profiling the wild-type entomopathogenic Photorhabdus luminescens subsp. laumondii TT01 to a luxS- deficient mutant unable to synthesize the type 2 quorum-sensing inducer AI-2. AI-2 was shown to regulate more than 300 targets involved in most compartments and metabolic pathways of the cell. AI-2 is located high in the hierarchy, as it controls the expression of several transcriptional regulators. The regulatory effect of AI-2 appeared to be dose dependent. The luxS- deficient strain exhibited decreased biofilm formation and increased type IV/V pilus-dependent twitching motility. AI-2 activated its own synthesis and transport. It also modulated bioluminescence by regulating the synthesis of spermidine. AI-2 was further shown to increase oxidative stress resistance, which is necessary to overcome part of the innate immune response of the host insect involving reactive oxygen species. Finally, we showed that the luxS- deficient strain had attenuated virulence against the lepidopteran Spodoptera littoralis . We concluded that AI-2 is involved mainly in early steps of insect invasion in P. luminescens .

Published
2006
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7. Steinernema sichuanense n. sp. (Rhabditida, Steinernematidae), a new species of entomopathogenic nematode from the province of Sichuan, east Tibetan Mts., China

Author

Mracek, Zdenek, Nguyen, Khuong B., Tailliez, Patrick, BOEMARE, Noël, Chen, Shulong, Czech Academy of Sciences [Prague] (CAS), Department of Entomology and Nematology, University of California [Davis] (UC Davis), University of California-University of California, Ecologie microbienne des insectes et interactions hôte-pathogène (EMIP), Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2), and Hebei University

Subjects
0106 biological sciences, Male, China, ENTOMOPATHOGENIC NEMATODE, 010607 zoology, DESCRIPTION, 01 natural sciences, Polymerase Chain Reaction, XENORHABDUS, 03 medical and health sciences, STEINERNEMA, Rhabditida, Soil, MOLECULAR, Species Specificity, INSECT PARASITE, Animals, Ecology, Evolution, Behavior and Systematics, Phylogeny, 030304 developmental biology, 0303 health sciences, Sex Characteristics, PHYLOGENETIC SYSTEMATIC, TAXONOMY, DNA, Helminth, [SDV.BA.ZI]Life Sciences [q-bio]/Animal biology/Invertebrate Zoology, Microscopy, Electron, Scanning, Female, NEW SPECIES
Abstract

Steinernema sichuanense n. sp. is characterized by male, female and IJ. For male, the spicules are robust with prominent rostrum; gubernaculum has blunt anterior end; cuneus is arrow-shaped, pointed posteriorly. Second-generation male has a prominent mucron. For female, tail usually has one to four papillae-like projections on tail tip; post anal swelling is absent. For IJ, body length is about 710 microm; lateral field has six ridges; the formula of lateral field is 2, 5, 6, 4, 2 with two prominent submarginal ridges; tail usually has a dorsal depression. In Steinernema affine/intermedium group, the IJ of S. sichuanense n. sp. differs from S. affine by its absence of the internal tail spine; differs from Steinernema beddingi by its six ridges in lateral field compared to 4 for S. beddingi. For male mucron is absent in both generations of S. affine, S. intermedium and S. beddingi, whereas it is present in the second-generation of S. sichuanense sp. n. Morphology and morphometrics of spicules and gubernacula of the four species in S. affine/intermedium group are quite different based on SEM photographs. For female, the postanal swelling is absent in the first-generation of S. sichuanense n. sp. whereas S. affine and S. intermedium have slight swelling and S. beddingi has conspicuous swelling. The new species is further recognized by characterization of sequences of ITS and D2/D3 regions of the ribosomal DNA. The symbiotic bacterium associated to S. sichuanense belongs to the species Xenorhabdus bovienii.

Published
2006
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8. Polyphasic study of Chryseobacterium strains isolated from diseased aquatic animals

Author

Bernardet, Jean Francois, Vancanneyt, M., Matte-Tailliez, O., Grisez, L., Tailliez, Patrick, Bizet, Chantal, Nowakowski, M., Kerouault, Brigitte, Swings, J., Unité de recherche Virologie et Immunologie Moléculaires (VIM (UR 0892)), Institut National de la Recherche Agronomique (INRA), Universiteit Gent = Ghent University [Belgium] (UGENT), Université Catholique de Louvain = Catholic University of Louvain (UCL), Ecologie microbienne des insectes et interactions hôte-pathogène (EMIP), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de la Recherche Agronomique (INRA), and Institut Pasteur [Paris]

Subjects
maladie des poissons, Elizabethkingia, diagnostic, Chryseobacterium, Applied Microbiology and Biotechnology, Fish Diseases, poisson, Genus, Flavobacteriaceae Infections, RNA, Ribosomal, 16S, Phylogeny, FISH DISEASE, 0303 health sciences, biology, Microbiology and Parasitology, Fatty Acids, Fishes, Microbiologie et Parasitologie, FATTY ACID ANALYSIS, RAPD, Bacterial Typing Techniques, Random Amplified Polymorphic DNA Technique, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, Phenotype, Electrophoresis, Polyacrylamide Gel, RANDOMLY AMPLIFIED POLYMORPHIC DNA, Anura, CONTROLE, agent pathogène, DNA, Bacterial, food.ingredient, taxonomie, Microbiology, ELIZABETHKINGIA, 03 medical and health sciences, food, PHENOTYPIC CHARACTERISTIC, WHOLE-CELL PROTEIN PROFILE, CHRYSEOBACTERIUM, POLYPHASIC TAXONOMY, SDS-PAGE, Animals, Elizabethkingia meningoseptica, Ribosomal DNA, Ecology, Evolution, Behavior and Systematics, 030304 developmental biology, 030306 microbiology, gène, Genes, rRNA, Ribosomal RNA, 16S ribosomal RNA, biology.organism_classification, Genes, Bacterial
Abstract

Correspondance: jean-francois.bernardet@jouy.inra.fr; International audience; Members of most Chryseottacterium species occur in aquatic environments or food products, while strains of some other species are pathogenic to humans and animals. A collection of 52 Chryseobacterium sp. strains isolated from diseased fish, one frog isolate and 22 reference strains were included in a polyphasic taxonomy study. Fourteen clusters of strains were delineated following the comparison of whole-cell protein profiles. Most of these clusters were confirmed when the phenotypic and RAPD profiles and the 16S rRNA gene sequences were compared. Fatty acid composition helped differentiate the Chryseobacterium strains from members of related genera. None of the fish isolates could be allocated to the two species previously reported from fish but two isolates belonged to C. joostei, while the frog isolate was identified as Elizabethkingia meningoseptica, a human pathogen previously included in the genus Chryseobacterium. Three clusters grouping from 3 to 13 isolates will probably constitute the core of new Chryseobacterium species but all other isolates occupied separate or uncertain positions in the genus. This study further demonstrated the overall high similarity displayed by most Chryseottacterium strains whatever the technique used and the resulting difficulty in delineating new species in the genus. Members of this bacterial group should be considered potential emergent pathogens in various fish and frog species, farming conditions and geographical areas

Published
2005
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9. Optical mapping as a routine tool for bacterial genome sequence finishing

Author

Brad Barbazuk, Zijin Du, Sophie Gaudriault, Helge B. Bode, Barry S. Goldman, John Henkhaus, Steven C. Slater, Steve Forst, Brad Goodner, Heidi Goodrich-Blair, Stacie Norton, Phil Latreille, Nancy M. Miller, Creg Darby, Monsanto Company, OpGen Technologies, Partenaires INRAE, Donald Danforth Plant Science Center, Saarland University [Saarbrücken], University of California [San Francisco] (UCSF), University of California, Department of Biological Sciences, The Open University [Milton Keynes] (OU), Ecologie microbienne des insectes et interactions hôte-pathogène (EMIP), Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2), Hiram College, Department of Bacteriology, Veterinary Laboratories Agency, and Arizona State University [Tempe] (ASU)

Subjects
XENORHABDUS, STEINERNEMA, SYMBIOTIC BACTERIA, OPTICAL MAPPING, ENTOMOPATHOGENIC NEMATODE, PHOTORHABDUS, METHODOLOGIE, CARTOGRAPHIE GENETIQUE, Restriction Mapping, Sequence assembly, Xenorhabdus, Genome, Contig Mapping, Plasmid, Image Processing, Computer-Assisted, bactérie entomopathogène, nématode, bactérie, Genetics, 0303 health sciences, biology, Methodology Article, Chromosomes, Bacterial, symbiose, Plasmids, Biotechnology, DNA, Bacterial, séquence nucleique, expression génique, lcsh:QH426-470, Sequence analysis, lcsh:Biotechnology, Bacterial genome size, 03 medical and health sciences, lcsh:TP248.13-248.65, ddc:570, Computer Simulation, 030304 developmental biology, Sequence (medicine), [SDV.GEN]Life Sciences [q-bio]/Genetics, écologie microbienne, 030306 microbiology, Sequence Analysis, DNA, biology.organism_classification, lcsh:Genetics, RNA, Ribosomal, DNA Transposable Elements, Genome, Bacterial
Abstract

Background In sequencing the genomes of two Xenorhabdus species, we encountered a large number of sequence repeats and assembly anomalies that stalled finishing efforts. This included a stretch of about 12 Kb that is over 99.9% identical between the plasmid and chromosome of X. nematophila. Results Whole genome restriction maps of the sequenced strains were produced through optical mapping technology. These maps allowed rapid resolution of sequence assembly problems, permitted closing of the genome, and allowed correction of a large inversion in a genome assembly that we had considered finished. Conclusion Our experience suggests that routine use of optical mapping in bacterial genome sequence finishing is warranted. When combined with data produced through 454 sequencing, an optical map can rapidly and inexpensively generate an ordered and oriented set of contigs to produce a nearly complete genome sequence assembly.

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