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Search Results: 1 - 10 of 947 matches for " Fabien Cottier "
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Communication in Fungi
Fabien Cottier,Fritz A. Mühlschlegel
International Journal of Microbiology , 2012, DOI: 10.1155/2012/351832
Abstract: We will discuss fungal communication in the context of fundamental biological functions including mating, growth, morphogenesis, and the regulation of fungal virulence determinants. We will address intraspecies but also interkingdom signaling by systematically discussing the sender of the message, the molecular message, and receiver. Analyzing communication shows the close coevolution of fungi with organisms present in their environment giving insights into multispecies communication. A better understanding of the molecular mechanisms underlying microbial communication will promote our understanding of the “fungal communicome.”
Communication in Fungi
Fabien Cottier,Fritz A. Mühlschlegel
International Journal of Microbiology , 2012, DOI: 10.1155/2012/351832
Abstract: We will discuss fungal communication in the context of fundamental biological functions including mating, growth, morphogenesis, and the regulation of fungal virulence determinants. We will address intraspecies but also interkingdom signaling by systematically discussing the sender of the message, the molecular message, and receiver. Analyzing communication shows the close coevolution of fungi with organisms present in their environment giving insights into multispecies communication. A better understanding of the molecular mechanisms underlying microbial communication will promote our understanding of the “fungal communicome.” 1. Introduction Any form of communication requires the existence of three obligatory components: a sender, a message, and a receiver. The process starts with the release of a message by a sender and ends with the understanding of the message by a receiver. This type of cycle has been developed with different degrees of complexity from prokaryote to higher eukaryotes optimizing fitness and adaptation for individual members and populations. The nature and mode of action of communication is as diverse as the response to the information it carries. Inter- and intraspecies communication has been widely studied analyzing the exchange of information between fungi and bacteria or fungi and plant cells [1, 2]. This review will focus predominantly on intraspecies fungal communication addressing key biological functions including mating, growth, morphological switching, or the regulation of virulence factor expression (Figure 1). We will show that in the fungal kingdom most of these mechanisms are controlled by a variety of messengers including small peptides, alcohols, lipids, and volatile compounds. Figure 1: Schematic representation of fungal intra and interspecies communication. The “sender” is an organism from the fungal kingdom and the “receiver” can be from any kingdom. Genes involved in messenger synthesis are represented as brown hexagons. Proteins involved in secretion or receiving the message are in orange and blue. 2. Peptides: Pheromones Pheromones have been known to act as an informative molecule since 1959 [3] and were reported to be involved in the sexual cycle of fungi in 1974 [4]. In the fungal kingdom, they are involved in the reconnaissance of compatible sexual partner to promote plasmogamy and karyogamy between two opposite mating types followed by meiosis. Taking the example of the extensively described sexual cycle of Saccharomyces cerevisiae, pheromones are diffusible peptides called a-factor (12 aa) when produced by
Msb2 Shedding Protects Candida albicans against Antimicrobial Peptides
Eva Szafranski-Schneider,Marc Swidergall,Fabien Cottier,Denis Tielker,Elvira Román,Jesus Pla,Joachim F. Ernst
PLOS Pathogens , 2012, DOI: 10.1371/journal.ppat.1002501
Abstract: Msb2 is a sensor protein in the plasma membrane of fungi. In the human fungal pathogen C. albicans Msb2 signals via the Cek1 MAP kinase pathway to maintain cell wall integrity and allow filamentous growth. Msb2 doubly epitope-tagged in its large extracellular and small cytoplasmic domain was efficiently cleaved during liquid and surface growth and the extracellular domain was almost quantitatively released into the growth medium. Msb2 cleavage was independent of proteases Sap9, Sap10 and Kex2. Secreted Msb2 was highly O-glycosylated by protein mannosyltransferases including Pmt1 resulting in an apparent molecular mass of >400 kDa. Deletion analyses revealed that the transmembrane region is required for Msb2 function, while the large N-terminal and the small cytoplasmic region function to downregulate Msb2 signaling or, respectively, allow its induction by tunicamycin. Purified extracellular Msb2 domain protected fungal and bacterial cells effectively from antimicrobial peptides (AMPs) histatin-5 and LL-37. AMP inactivation was not due to degradation but depended on the quantity and length of the Msb2 glycofragment. C. albicans msb2 mutants were supersensitive to LL-37 but not histatin-5, suggesting that secreted rather than cell-associated Msb2 determines AMP protection. Thus, in addition to its sensor function Msb2 has a second activity because shedding of its glycofragment generates AMP quorum resistance.
Application of LED Type Lamps in Domestic and Public Utilities and Gain Capability to Run New Small Investments in Rwanda  [PDF]
Mukundufite Fabien
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.510093
Abstract:

The Rwandan State-run Energy Water and Sanitation Authority Company (EWSA) is rapidly increasing the number of population having access to electrical power energy. 30% of electrical energy is used in lighting. The incandescent bulbs, compact fluorescent lamp bulbs as well as fluorescent tubes are mostly used to convert electrical energy into light. The said light sources have many disadvantages such as excessive power consumption leading to giant bills of electricity, short life span leading to continuous replacement of lamps, and emission of CO2. Application of light-emitting diode (LED) lamps in lighting in long term suppresses the aforementioned problems resulting into saving of money that will be used for running new small investments.

Le roman d’Afrique noire entre ruse et violence : le pouvoir de la langue chez Henri Lopes, Ahmadou Kourouma et Sony Labou Tansi
Christine Le Quellec Cottier
Synergies Afrique Centrale et de l'Ouest , 2007,
Abstract:
The bZIP Transcription Factor Rca1p Is a Central Regulator of a Novel CO2 Sensing Pathway in Yeast
Fabien Cottier,Martine Raymond,Oliver Kurzai,Marianne Bolstad,Worraanong Leewattanapasuk,Claudia Jiménez-López,Michael C. Lorenz,Dominique Sanglard,Libu?e Váchová,Norman Pavelka,Zdena Palková,Fritz A. Mühlschlegel
PLOS Pathogens , 2012, DOI: 10.1371/journal.ppat.1002485
Abstract: Like many organisms the fungal pathogen Candida albicans senses changes in the environmental CO2 concentration. This response involves two major proteins: adenylyl cyclase and carbonic anhydrase (CA). Here, we demonstrate that CA expression is tightly controlled by the availability of CO2 and identify the bZIP transcription factor Rca1p as the first CO2 regulator of CA expression in yeast. We show that Rca1p upregulates CA expression during contact with mammalian phagocytes and demonstrate that serine 124 is critical for Rca1p signaling, which occurs independently of adenylyl cyclase. ChIP-chip analysis and the identification of Rca1p orthologs in the model yeast Saccharomyces cerevisiae (Cst6p) point to the broad significance of this novel pathway in fungi. By using advanced microscopy we visualize for the first time the impact of CO2 build-up on gene expression in entire fungal populations with an exceptional level of detail. Our results present the bZIP protein Rca1p as the first fungal regulator of carbonic anhydrase, and reveal the existence of an adenylyl cyclase independent CO2 sensing pathway in yeast. Rca1p appears to regulate cellular metabolism in response to CO2 availability in environments as diverse as the phagosome, yeast communities or liquid culture.
Instructional Design Rationale with QOC: A Model Driven Engineering and Domain Specific Modeling Approach
El Amine Ouraiba,Christophe Choquet,Philippe Cottier
Lecture Notes in Engineering and Computer Science , 2011,
Abstract:
Domain Specific Supports for Design Rationale of Open Pedagogical Scenarios
El Amine Ouraiba,Christophe Choquet,Philippe Cottier
IAENG International Journal of Computer Science , 2011,
Abstract:
Does T Helper Differentiation Correlate with Resistance or Susceptibility to Infection with L. major? Some Insights From the Murine Model
Fabienne Tacchini-Cottier,Tiffany Weinkopff
Frontiers in Immunology , 2012, DOI: 10.3389/fimmu.2012.00032
Abstract: The murine model of Leishmania major infection has been an invaluable tool in understanding T helper differentiation in vivo. The initial evidence for a role of distinct CD4+ T helper subsets in the outcome of infection was first obtained with this experimental model. The development of CD4+ Th1 cells was associated with resolution of the lesion, control of parasite replication, and resistance to re-infection in most of the mouse strains investigated (i.e., C57BL/6). In contrast, differentiation of CD4+ Th2 cells correlated with the development of unhealing lesions, and failure to control parasite load in a few strains (i.e., BALB/c). Since these first reports, an incredible amount of effort has been devoted to understanding the various parameters involved in the differentiation of these, and more recently discovered T helper subsets such as Th17 and T regulatory cells. The discovery of cross-talk between T helper subsets, as well as their plasticity force us to reevaluate the events driving a protective/deleterious T helper immune response following infection with L. major in mice. In this review, we describe the individual contributions of each of these CD4+ T helper subsets following L. major inoculation, emphasizing recent advances in the field, such as the impact of different substrains of L. major on the pathogenesis of disease.
The yeast three-hybrid system as an experimental platform to identify proteins interacting with small signaling molecules in plant cells: Potential and limitations
Stéphanie Cottier,Ji?í Svoboda,Erich Kombrink
Frontiers in Plant Science , 2011, DOI: 10.3389/fpls.2011.00101
Abstract: Chemical genetics is a powerful scientific strategy that utilizes small bioactive molecules as experimental tools to unravel biological processes. Bioactive compounds occurring in nature represent an enormous diversity of structures that can be used to dissect functions of biological systems. Once the bioactivity of a natural or synthetic compound has been critically evaluated the challenge remains to identify its molecular target and mode of action, which usually is a time-consuming and labor-intensive process. To facilitate this task, we decided to implement the yeast three-hybrid (Y3H) technology as a general experimental platform to scan the whole Arabidopsis proteome for targets of small signaling molecules. The Y3H technology is based on the yeast two-hybrid system and allows direct cloning of proteins that interact in vivo with a synthetic hybrid ligand, which comprises the biologically active molecule of interest covalently linked to methotrexate (Mtx). In yeast nucleus the hybrid ligand connects two fusion proteins: the Mtx part binding to dihydrofolate reductase fused to a DNA-binding domain (encoded in the yeast strain), and the bioactive molecule part binding to its potential protein target fused to a DNA-activating domain (encoded on a cDNA expression vector). During cDNA library screening, the formation of this ternary, transcriptional activator complex leads to reporter gene activation in yeast cells, and thereby allows selection of the putative targets of small bioactive molecules of interest. Here we present the strategy and experimental details for construction and application of a Y3H platform, including chemical synthesis of different hybrid ligands, construction of suitable cDNA libraries, the choice of yeast strains, and appropriate screening conditions. Based on the results obtained and the current literature we discuss the perspectives and limitations of the Y3H approach for identifying targets of small bioactive molecules.
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