Search results for " Parasitology"
showing 10 items of 651 documents
The effects of parasite age and intensity on variability in acanthocephalan-induced behavioural manipulation.
2008
10 pages; International audience; Numerous parasites with complex life cycles are able to manipulate the behaviour of their intermediate host in a way that increases their trophic transmission to the definitive host. Pomphorhynchus laevis, an acanthocephalan parasite, is known to reverse the phototactic behaviour of its amphipod intermediate host, Gammarus pulex, leading to an increased predation by fish hosts. However, levels of behavioural manipulation exhibited by naturally-infected gammarids are extremely variable, with some individuals being strongly manipulated whilst others are almost not affected by infection. To investigate parasite age and parasite intensity as potential sources o…
Bioconversion of amino acids into flavouring alcohols and esters by Erwinia carotovora subsp. atroseptica
1991
International audience; Erwinia carotovora subsp. atroseptica produced flavour compounds when infecting endives (Cichorium intybus). These compounds were identified as esters and branched-chain alcohols.They were produced from amino acids and some of them such as methionol, methionol acetate, isobutanol, isobutyl acetate, beta-phenyl ethanol and tryptophol were produced with good yields.
Characterization and evolution of two bacteriome-inhabiting symbionts in cixiid planthoppers (Hemiptera: Fulgoromorpha: Pentastirini).
2009
International audience; Like other plant sap-sucking insects, planthoppers within the family Cixiidae (Insecta: Hemiptera: Fulgoromorpha) host a diversified microbiota. We report the identification and first molecular characterization of symbiotic bacteria in cixiid planthoppers (tribe: Pentastirini). Using universal eubacterial primers we first screened the eubacterial 16S rRNA sequences in Pentastiridius leporinus (Linnaeus) with PCR amplification, cloning, and restriction fragment analysis. We identified three main 16S rRNA sequences that corresponded to a Wolbachia bacterium, a plant pathogenic bacterium, and a novel gammaproteobacterial symbiont. A fourth bacterial species affiliated w…
Fatty acid hydroperoxide lyase of green bell pepper: cloning in Yarrowia lipolytica and biogenesis of volatile aldehydes
2004
Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Fatty acid hydroperoxide lyase (HPO lyase) is a cytochrome P450 acting on fatty acid hydroperoxides in many organisms. The expression of green bell pepper HPO lyase in the yeast Yarrowia lipolytica is described for the first time. HPO lyase activity from yeast extract and whole yeast cells is measured and aldehydes production from yeast extract and whole yeast cells is compared. 1200 U/L reaction medium were obtained after 96 h of culture on olive oil rich me…
Mycelial development of Fusarium oxysporum in the vicinity of tomato roots
1999
The patterns of mycelial development (length and branching) of five strains of Fusarium oxysporum were measured in the vicinity of tomato and wheat roots. Two strains were of f. sp. lycopersici, two of f. sp. radicis-lycopersici and the fifth was a non-pathogenic strain currently used as a biocontrol agent. Hyphal extension and branching were measured microscopically using a CCD camera and an image analyser. Furthermore, the role of soluble root exudates, insoluble root materials, glucose supply, and nitrogen supply (casamino acids) on mycelial development was investigated. Each strain had its own pattern of development in the absence of a root. Fungal development of all five strains was st…
Colonization of adventitious roots ofMedicago truncatulabyPseudomonas fluorescensC7R12 as affected by arbuscular mycorrhiza
2008
Pseudomonas fluorescens C7R12 was previously shown to promote colonization of Medicago truncatula roots by Glomus mosseae BEG12. To gain more insight into the interaction between C7R12 and BEG12, the cell organization of C7R12 was characterized on adventitious roots mycorrhized or not with BEG12 and on extraradical hyphae. Bacterial cell observations were made using the immuno-fluorescence technique and confocal laser scanning microscopy. Five types of cell organization, so-called organization types (OT), were identified: small or large single cells, cells by pair and cells in microcolonies or in strings. The frequencies of each OT on the roots were expressed as the percentage of observatio…
A mycorrhiza helper bacterium enhances ectomycorrhizal and endomycorrhizal symbiosis of Australian Acacia species.
2003
The aims of this study were to test the effects of a mycorrhiza helper bacterium (MHB), Pseudomonas monteilii strain HR13 on the mycorrhization of (1) an Australian Acacia, A. holosericea, by several ectomycorrhizal fungi or one endomycorrhizal fungus Glomus intraradices, and (2) several Australian Acacia species by Pisolithus alba strain IR100 under glasshouse conditions. Bacterial inoculant HR13 significantly promoted ectomycorrhizal colonization for all the Acacia species, from 45.8% ( A. mangium) to 70.3% ( A. auriculiformis). A stimulating effect of HR13 on the ectomycorrhizal establishment was recorded with all the fungal isolates (strains of Pisolithus and Scleroderma). The same effe…
Different bacteria can enhance the micropropagation response of Cotoneaster lacteus (Rosaceae)
1998
C. MONIER, E. BOSSIS, C. CHABANET AND R. SAMSON. 1998. Cotoneaster species are widely used ornamental shrubs, and research is under way to select genotypes which are more resistant to fire blight by somaclonal variation. During the establishment of micropropagation, one genotype, Cotoneaster lacteus, showed the development of endogenous bacterial contaminants. Two strains were isolated from in vitro explants: Bacillus pumilus and Alcaligenes faecalis. These two strains, and some Pseudomonas fluorescens and Ps. putida, promoted in vitro multiplication and rooting of explants. In Pseudomonas strains, rooting enhancing capacity appeared to be related to indole-3-acetic acid (IAA) production, a…
Correlational selection on pro- and anti-inflammatory effectors.
2012
9 pages; International audience; Parasites impose a permanent threat for hosts. As a consequence, immune defenses are important for host fitness. However, the immune response can also produce self-damage and impair host fitness if not properly regulated. Effectors that up- and downregulate the immune response should, therefore, evolve in concert, and be under the action of correlational selection. To address this issue, we assessed the shape of the selection operating on pro- and anti-inflammatory effectors following an inflammatory challenge in laboratory mice. We found that selection acts on the combination of these two traits as individuals that produced large amount of pro-inflammatory …
Intraspecific variability in host manipulation by parasites
2011
8 pages; International audience; Manipulative parasites have the capacity to alter a broad range of phenotypic traits in their hosts, extending from colour, morphology and behaviour. While significant attention has been devoted to describing the diversity of host manipulation among parasite clades, and testing the adaptive value of phenotypic traits that can be manipulated, there is increasing evidence that variation exists in the frequency and intensity of the changes displayed by parasitized individuals within single host-manipulative parasite systems. Such variability occurs within individuals, between individuals of a same population, and across populations. Here we review the non-genet…