[Show abstract][Hide abstract] ABSTRACT: Parasitic manipulations of host behaviour are known from a wide range of host-parasite associations. However, the understanding of these phenomena is far from complete and detailed investigation of their proximate causes is needed. Many studies report behavioural modifications, such as altered feeding rates in tsetse fly (Glossina) infected with the mature transmissible stage (i.e. metacyclic) of the trypanosomes. Here, bidimensional (2D) gel electrophoresis and mass spectrometry were employed to analyse and compare the head proteome between four Glossina palpalis gambiensis categories (uninfected, refractory, mature infection, immature infection). Twenty-four protein spots specifically present or absent in the head of metacyclic-infected flies were observed. These protein spots were subsequently identified and functionally classified as glycolitic, neurotransmiter synthesis, signalling, molecular chaperone and transcriptional regulation proteins. Our results indicate altered energy metabolism in the head of metacyclic-infected tsetse flies. Some of the proteins identified, such as casein kinase 2 and jun kinase have previously been shown to play critical roles in apoptosis in insect neurones. In addition, we found two pyridoxal-dependent decarboxylases (dopa decarboxylase and alpha methyldopa hypersensitive protein), suggesting a modification of serotonin and/or dopamine in the brain of metacyclic-infected tsetse flies. Our data pave the way for future investigation of the alteration of the glossina central nervous system during infection by trypanosomes.
[Show abstract][Hide abstract] ABSTRACT: Despite increasing evidence of host phenotypic manipulation by parasites, the underlying mechanisms causing infected hosts to act in ways that benefit the parasite remain enigmatic in most cases. Here, we used proteomics tools to identify the biochemical alterations that occur in the head of the cricket Nemobius sylvestris when it is driven to water by the hairworm Paragordius tricuspidatus. We characterized host and parasite proteomes during the expression of the water-seeking behaviour. We found that the parasite produces molecules from the Wnt family that may act directly on the development of the central nervous system (CNS). In the head of manipulated cricket, we found differential expression of proteins specifically linked to neurogenesis, circadian rhythm and neurotransmitter activities. We also detected proteins for which the function(s) are still unknown. This proteomics study on the biochemical pathways altered by hairworms has also allowed us to tackle questions of physiological and molecular convergence in the mechanism(s) causing the alteration of orthoptera behaviour. The two hairworm species produce effective molecules acting directly on the CNS of their orthoptera hosts.
[Show abstract][Hide abstract] ABSTRACT: Phylogenetically unrelated parasites often increase the chances of their transmission by inducing similar phenotypic changes in their hosts. However, it is not known whether these convergent strategies rely on the same biochemical precursors. In this paper, we explored such aspects by studying two gammarid species (Gammarus insensibilis and Gammarus pulex; Crustacea: Amphipoda: Gammaridae) serving as intermediate hosts in the life cycle of two distantly related parasites: the trematode, Microphallus papillorobustus and the acanthocephalan, Polymorphus minutus. Both these parasite species are known to manipulate the behaviour of their amphipod hosts, bringing them towards the water surface, where they are preferentially eaten by aquatic birds (definitive hosts). By studying and comparing the brains of infected G. insensibilis and G. pulex with proteomics tools, we have elucidated some of the proximate causes involved in the parasite-induced alterations of host behaviour for each system. Protein identifications suggest that altered physiological compartments in hosts can be similar (e.g. immunoneural connexions) or different (e.g. vision process), and hence specific to the host-parasite association considered. Moreover, proteins required to alter the same physiological compartment can be specific or conversely common in both systems, illustrating in the latter case a molecular convergence in the proximate mechanisms of manipulation.
Proceedings of the Royal Society B: Biological Sciences 12/2006; 273(1603):2869-77. · 5.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: One of the most fascinating anti-predator responses displayed by parasites is that of hairworms (Nematomorpha). Following the ingestion of the insect host by fish or frogs, the parasitic worm is able to actively exit both its host and the gut of the predator. Using as a model the hairworm, Paragordius tricuspidatus, (parasitizing the cricket Nemobius sylvestris) and the fish predator Micropterus salmoïdes, we explored, with proteomics tools, the physiological basis of this anti-predator response. By examining the proteome of the parasitic worm, we detected a differential expression of 27 protein spots in those worms able to escape the predator. Peptide Mass Fingerprints of candidate protein spots suggest the existence of an intense muscular activity in escaping worms, which functions in parallel with their distinctive biology. In a second step, we attempted to determine whether the energy expended by worms to escape the predator is traded off against its reproductive potential. Remarkably, the number of offspring produced by worms having escaped a predator was not reduced compared with controls.
[Show abstract][Hide abstract] ABSTRACT: We report on the modification of the Aedes aegypti larval proteome following infection by the microsporidian parasite Vavraia culicis. Mosquito larvae were sampled at 5 and 15 days of age to compare the effects of infection when the parasite was in two different developmental stages. Modifications of the host proteome due to the stress of infection were distinguished from those of a more general nature by treatments involving hypoxia. We found that the major reaction to stress was the suppression of particular protein spots. Older (15 days) larvae reacted more strongly to infection by V. culicis (46% of the total number of spots affected; 17% for 5 days larvae), while the strongest reaction of younger (5 days) larvae was to hypoxia for pH range 5-8 and to combined effects of infection and hypoxia for pH range 3-6. MALDI-TOF results indicate that proteins induced or suppressed by infection are involved directly or indirectly in defense against microorganisms. Finally, our MALDI-TOF results suggest that A. aegypti larvae try to control or clear V. culicis infection and also that V. culicis probably impairs the immune defense of this host via arginases-NOS competition.
International Journal for Parasitology 12/2005; 35(13):1385-97. · 3.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The parasitic Nematomorph hairworm, Spinochordodes tellinii (Camerano) develops inside the terrestrial grasshopper, Meconema thalassinum (De Geer) (Orthoptera: Tettigoniidae), changing the insect's responses to water. The resulting aberrant behaviour makes infected insects more likely to jump into an aquatic environment where the adult parasite reproduces. We used proteomics tools (i.e. two-dimensional gel electrophoresis (2-DE), computer assisted comparative analysis of host and parasite protein spots and MALDI-TOF mass spectrometry) to identify these proteins and to explore the mechanisms underlying this subtle behavioural modification. We characterized simultaneously the host (brain) and the parasite proteomes at three stages of the manipulative process, i.e. before, during and after manipulation. For the host, there was a differential proteomic expression in relation to different effects such as the circadian cycle, the parasitic status, the manipulative period itself, and worm emergence. For the parasite, a differential proteomics expression allowed characterization of the parasitic and the free-living stages, the manipulative period and the emergence of the worm from the host. The findings suggest that the adult worm alters the normal functions of the grasshopper's central nervous system (CNS) by producing certain 'effective' molecules. In addition, in the brain of manipulated insects, there was found to be a differential expression of proteins specifically linked to neurotransmitter activities. The evidence obtained also suggested that the parasite produces molecules from the family Wnt acting directly on the development of the CNS. These proteins show important similarities with those known in other insects, suggesting a case of molecular mimicry. Finally, we found many proteins in the host's CNS as well as in the parasite for which the function(s) are still unknown in the published literature (www) protein databases. These results support the hypothesis that host behavioural changes are mediated by a mix of direct and indirect chemical manipulation.
Proceedings of the Royal Society B: Biological Sciences 11/2005; 272(1577):2117-26. · 5.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Peruvian potato cyst nematode populations were analysed to assess both their inter- and intraspecific similarities. ITS--RFLP and two satellite DNA sequences were used as taxonomic tools. Both techniques have confirmed that the Peruvian populations have as their closest relatives the European Globodera pallida, despite the detection of clear differences that prevents us from assigning these South American populations unambiguously to any Globodera species. A more precise study of the variability of these Peruvian populations was investigated and they were compared with the imported European populations using protein (2-DGE) and DNA (RAPD) datasets. The clear distinction between the Peruvian and the European populations was confirmed and, inside each group, no correlation was found between the pathotype classification and the observed clustering of the populations. Surprisingly, while RAPDs revealed a higher variability in the Peruvian group than in the European one, some characteristic proteins were found by 2-DGE in some European populations, whereas it was impossible to find any in the Peruvian populations. It is concluded that the primary founders of the European populations may have an origin other than that of the Peruvian populations involved in this study.
[Show abstract][Hide abstract] ABSTRACT: Two major proteins, Mcf-A67 and Mcf-B66, were identified by mini two-dimensional polyacrylamide gel electrophoresis in order to distinguish the two European quarantine root-knot nematodes, Meloidogyne chitwoodi and M. fallax, from eight other species. These quarantine proteinic markers have been microsequenced after enzymatic digestion. The internal amino acid sequences exhibit similarities to members of a family of low molecular weight intracellular lipid-binding proteins. Moreover, to explore a simple, rapid, and inexpensive way to identify the two quarantine nematodes, dot blot hybridizations were performed using an antiserum (A67) produced from the longest amino-acid sequence of the protein Mcf-A67. Although several proteins stained on the M. chitwoodi and M. fallax western blot membranes, the two nematodes were easily distinguished from other root-knot nematodes, on dot blot assays with soluble proteins extracted from a single female. Because of its specificity and sensitivity, the use of the A67 antiserum to improve the diagnosis of the two European quarantine root-knot nematodes is discussed.
European Journal of Plant Pathology 01/2001; 107(8):821-832. · 1.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Protein variation and phenetic relationships in four tropical root-knot nematode species were studied by two-dimensional gel electrophoresis (2-DGE). Total soluble protein extracts from white females of Meloidogyne incognita, M. javanica, M. arenaria and M. mayaguensis were separated by electrophoresis, and the two-dimensional (2-D) profiles were compared with a computed analysis system. A four species global comparison allowed detection of 4 and 13 specific proteins for M. arenaria and M. mayaguensis, respectively, among the 498 proteinic spots detected on the synthetic image (or 'master'). Such proteins were not detected for M. incognita and M. javanica. Nevertheless, species discriminative proteins and shared proteins have been identified in all pairwise comparisons between species. In addition, the similarity index and the genetic distances between the different isolates studied were calculated on the basis of homologous polymorphic spots. A dendrogram was constructed according to the UPGMA method. Significance of the results from phenetic study was assessed by bootstrap analysis. M. incognita, M. javanica and M. arenaria showed high similarity. M. mayaguensis was more distant. These results are in agreement with RAPD and RFLP studies.La variabilité protéique et les relations phénétiques de quatre espèces tropicales de nématodes galligènes ont été étudiées par électrophorèse sur gel en deux dimensions (2-DGE). Les protéines solubles totales extraites de femelles blanches de Meloidogyne incognita, M. javanica, M. arenaria et M. mayaguensis ont été séparées par électrophorèse et les profils bidimensionels comparés à l'aide d'un système d'analyse informatisé. Une comparaison globale des quatre espèces a permis de détecter quatre protéines spécifiques pour M. arenaria et 13 pour M. mayaguensis parmi les 498 taches protéiques présentes sur l'image de référence (ou “master”). De telles protéines n'ont été détectées ni pour M. incognita ni pour M. javanica. Néanmoins, des protéines discriminantes et communes ont été identifiées lors de toutes les comparaisons d'espèces deux à deux. De plus, les indices de similarité et les distances génétiques entre les différents isolats étudiés ont été calculés à partir des taches polymorphes homologues. Les dendrogrammes ont été construits selon la méthode UPGMA. La signification des résultats phénétiques a été estimée par une analyse “bootstrap”. M. incognita, M. javanica et M. arenaria sont très proches. M. mayaguensis est plus distant. Ces résultats sont en accord avec ceux d'études en RAPD et RFLP.
[Show abstract][Hide abstract] ABSTRACT: The variation of total soluble protein extracts from white adult females of seven Meloidogyne chitwoodi and three M. fallax isolates were studied using two dimensional gel electrophoresis (2-DGE). The 2-D protein profiles were compared with a computed analysis system. A synthetic image or 'master' was constructed from proteinic spots present in each isolate. The comparison of the two species allowed detection of qualitative and, to a lesser extent, quantitative variations. Among the 243 proteinic spots present on the master, we have identified 75 monomorphic spots for both species and nine discriminative proteins for each of the two species. In addition, two isoelectric point variants and two quantitative variants were observed. The similarity index and the genetic distances between the ten isolates were calculated on the basis of homologous polymorphic spots. Dendrograms were constructed according to the UPGMA method. Significance of the results from the phenetic study was assessed by bootstrap analysis. The results from the clustering analysis allowed differentiation between both species and showed intraspecific variation among the M. chitwoodi isolates equal to that among the M. fallax isolates. Variabilite proteique de Meloidogyne chitwoodi et M. fallax etudiee par analyse informatisee d'electrophoregrammes bidimensionnels - La variabilite d'extraits proteiques solubles totaux de femelles blanches adultes de sept isolats de Meloidogyne chitwoodi et trois de M. fallax a ete etudiee par electrophorese sur gel en deux dimensions (2-DGE). Les profils proteiques bidimensionels ont ete compares grace a un systeme d'analyse informatise. Une image synthetique, ou image de reference, a ete construite a partir des spots proteiques toujours observes dans chaque isolat. La comparaison des deux especes a permis de detecter des variations qualitatives et, dans une moindre mesure, quantitatives. Parmi les 243 taches proteiques presentes sur l'image de reference, ont ete identifies 75 polypeptides communs aux deux especes et neuf proteines discriminantes pour chacune des deux especes. De plus, deux variants de point isoelectrique et deux variants quantitatifs ont ete observes. Les indices de similarite et les distances genetiques entre les dix isolats ont ete etudies a partir des taches polymorphes homologues. Les dendrogrammes ont ete construits selon la methode UPGMA. La signification des resultats phenetiques a ete estimee par une analyse "bootstrap". Les resultats de l'analyse en grappes ont permis de differencier les deux especes et ont revele une variabilite intraspecifique similaire entre isolats de M. chitwoodi et isolats de M. fallax.