Search

Esta obra se enmarca en la continuidad de las investigaciones iniciadas en 2008 sobre Sabino Berthelot y pretende completar, a modo de apéndice documental, una obra publicada en 2016 sobre este personaje de notable trascendencia histórica en el archipiélago canario: Un francés entre guanches. Sabino Berthelot y las Islas Canarias. Reúne documentos elaborados por él entre 1848 y 1869, desde Santa Cruz de Tenerife, en el ámbito de su correspondencia consular y comercial con el Ministerio de Asuntos Exteriores francés. Algunos de dichos escritos ya se habían dado a conocer al público en las décadas de 1850 y 1860 a través de revistas francesas, pero la gran mayoría permanecían inéditos. Además de que con ellos se descubren facetas de la personalidad del antiguo cónsul, se trata de nuevas fuentes históricas para el estudio sobre la historia del Archipiélago durante la segunda mitad del siglo XIX.

International audience; We present in this paper the voting games with a purpose that were developed around JeuxDeMots, a central game aiming at creating a lexical network for French. We show that such lightweight applications can help collect quality language resources very efficiently and we advocate for a common platform for such voting games for language resources.

International audience; Correcting errors in a data set is a critical issue. This task can be either handmade by experts, or by crowdsourcing methods or automatically done using algorithms. Although even if the rate of errors present in a given lexical network is rather low, it is important to reduce it. We present here automatic methods for detecting potential secondary errors that would result from automatic inference mechanisms when they rely on an initial error manually detected. Encouraging results also invite us to consider strategies that would automatically detect "erroneous" initial relations, which could lead to the automatic detection of the majority of errors in a lexical-semantic network.

In this work, we investigate the investment of entomopathogenic Steinernema nematodes (Rhabditidae) in their symbiotic association with Xenorhabdus bacteria (Enterobacteriaceae). Their life cycle comprises two phases: (1) a free stage in the soil, where infective juveniles (IJs) of the nematode carry bacteria in a digestive vesicle and search for insect hosts, and (2) a parasitic stage into the insect where bacterial multiplication, nematode reproduction, and production of new IJs occur. Previous studies clearly showed benefits to the association for the nematode during the parasitic stage, but preliminary data suggest the existence of costs to the association for the nematode in free stage. IJs deprived from their bacteria indeed survive longer than symbiotic ones. Here we show that those bacteria-linked costs and benefits lead to a trade-off between fitness traits of the symbiotic nematodes. Indeed IJs mortality positively correlates with their parasitic success in the insect host for symbiotic IJs and not for aposymbiotic ones. Moreover mortality and parasitic success both positively correlate with the number of bacteria carried per IJ, indicating that the trade-off is induced by symbiosis. Finally, the trade-off intensity depends on parental effects and, more generally, is greater under restrictive environmental conditions.

Human brains can be seen as knowledge processors in a distributed system. Each of them can achieve, conscious or not, a small part of a treatment too important to be done by one. These are also "hunter / gatherers" of knowledge. Provided that the number of contributors is large enough, the results are usually better quality than if they were the result of the activity of a single person, even if it is a domain expert. This type of activity is done via online games.

International audience; Steinernema species are entomopathogenic nematodes associated with Xenorhabdus bacteria. The life cycle of these associations is composed of two stages: (1) a free stage in the soil, where infective juveniles (IJs), which carry bacteria in their guts, search for new insect hosts; and (2) a parasitic stage, where the IJs infect insects, release their Xenorhabdus symbionts and reproduce in order to produce new IJs. Previous studies clearly showed benefits to the association for several Steinernema species during the parasitic stage. Nevertheless, no study has so far explored, during the free stage, the existence of costs or benefits to the association for different Steinernema. Here, we compared the survival of both symbiotic and aposymbiotic IJs in two nematode species: (1) Steinernema carpocapsae-exhibiting IJs that carry a high number of Xenorhabdus cells in their guts; and (2) its closely relative species, S. scapterisci-exhibiting IJs, that carry very few Xenorhabdus cells in their guts. We showed that the bacterial symbionts were costly for S. carpocapsae by increasing IJs' mortality but not for S. scapterisci. This difference in cost induced by bacteria to IJs during the free stage could be correlated with the difference in the numbers of bacteria carried by IJs of each nematode species.

Protoancylodiscoides malapteruri n. sp. Monogene parasite branchial du poisson electrique Malapterurus electricus Gmelin a ete recolte au Cameroun dans une seule localite du bassin de la Sanaga. Ce parasite est caracterise par la presence, au niveau du hapteur, de deux onchia (l'un ventral, l'autre dorsal), de quatre types d'uncinuli et, au niveau de l'appareil genital, d'un penis tubulaire court, non enroule, d'une piece accessoire particuliere, d'un canal deferent entourant la branche intestinale gauche et d'un vagin a ouverture laterale droite. La position systematique de ce Monogene au sein de l'ordre des Dactylogyridea est discutee et la diagnose du genre Protoancylodiscoides est modifiee. Protoancylodiscoides malapteruri n. sp., a monogenean gill parasite of Malapterurus electricus Gmelin in southern Cameroon, is described. This worm is characterised by the presence in the haptor of two onchia (one ventral and one dorsal) and four different types of uncinuli (hooklets), and in the genital system, a short tubular penis (never coiled), a special accessory piece, a vas deferens which winds arounds the left intestinal crus and a vagina with a lateral aperture on the right side. The systematic position of this monogenean within the order Dactylogyridea is discussed and the diagnosis of the genus Protoancylodiscoides is amended.

Natural hybridization of Barbus barbus and B. meridionalis has been demonstrated in southern France. A genetical study (isozyme electrophoresis) of these species and their hybrids revealed the characteristics of hybridization. Ten enzyme markers and five morphological parameters were used to distinguish between the two parent species. Enzymatic divergence between the parent species included fixed allelic differences at certain loci and reduction in enzymatic activity, including the silencing of certain genes. A morphological study revealed a good correlation between the isozyme markers and morphological characters. Backcrosses were observed and this raises the question of the integrity of the parent species.

In southern France, Diplozoon gracile (Monogenea, Polyopisthocotylea), parasitizes four sympatric cyprinids. One of these host species, Barbus meridionalis, naturally hybridizes with another species of barbel, Barbus barbus, which is never parasitized by D. gracile under natural conditions. This hybridization has previously been studied and described as an introgression of B. barbus by B. meridionalis. The hybrids are parasitized by D. gracile, and parasite prevalence increases in proportion to the introgression rate, i.e., the percentage of B. meridionalis genes. The causes for this preferential distribution of the parasite in the hybrid population are analysed on the basis of ecological and ethological differences between the two parent species.

In this work, we investigate the investment of entomopathogenic Steinernema nematodes (Rhabditidae) in their symbiotic association with Xenorhabdus bacteria (Enterobacteriaceae). Their life cycle comprises two phases: (1) a free stage in the soil, where infective juveniles (IJs) of the nematode carry bacteria in a digestive vesicle and search for insect hosts, and (2) a parasitic stage into the insect where bacterial multiplication, nematode reproduction, and production of new IJs occur. Previous studies clearly showed benefits to the association for the nematode during the parasitic stage, but preliminary data suggest the existence of costs to the association for the nematode in free stage. IJs deprived from their bacteria indeed survive longer than symbiotic ones. Here we show that those bacteria-linked costs and benefits lead to a trade-off between fitness traits of the symbiotic nematodes. Indeed IJs mortality positively correlates with their parasitic success in the insect host for symbiotic IJs and not for aposymbiotic ones. Moreover mortality and parasitic success both positively correlate with the number of bacteria carried per IJ, indicating that the trade-off is induced by symbiosis. Finally, the trade-off intensity depends on parental effects and, more generally, is greater under restrictive environmental conditions.

International audience; Isolation and identification of native nematode-bacterial associations in the field are necessary for successful control of endemic pests in a particular location. No study has yet been undertaken to recover and identify EPN in metropolitan France. In the present paper, we provide results of a survey of EPN and their symbiotic bacteria conducted in Herault and Gard regions in Southern France. Molecular characterization of isolated nematodes depicted three different Steinernema species and one Heterorhabditis species, H. bacteriophora. Steinernema species recovered were identified as: S. feltiae and S. affine and an undescribed species. Xenorhabdus symbionts were identified as X. bovienii for both S. feltiae and S. affine. Phylogenetic analysis placed the new undescribed Steinernema sp. as closely related to S. arenarium but divergent enough to postulate that it belongs to a new species within the "glaseri-group"., The Xenorhabdus symbiont from this Steinernema sp. was identified as X. kozodoii. All Heterorhabditis isolates recovered were diagnosed as H. bacteriophoro and their bacterial symbionts were identified as Photorhabdus luminescens. Molecular characterization of these nematodes enabled the distinction of two different H. bacteriophora strains. Bacterial symbiontic, strains of these two H. bacteriophora strains were identified as P. lurninescens ssp. kayaii and P. luminescens ssp. laumondii

The level of specialization of the entomopathogenic nematode Steinernema scapterisci with its native Xenorhabdus symbiont was investigated by testing (1) the influence of non-native bacterial strains on nematode fitness within an insect-host (Galleria mellonella) and (2) specificity of the association between the nematode infective juveniles and non-native bacteria. All non-native Xenorhabdus spp. or Photorhabdus spp. strains tested were mutualistically associated with other entomopathogenic nematodes in nature. We showed that most of the Xenorhabdus spp. strains tested led to an insignificant difference of the nematode's fitness compared to the one obtained with the native bacterium. Conversely, Photorhabdus spp. strains almost entirely abolished nematode reproduction. The phylogenetic analysis of bacterial strains tested, showed that there was a negative correlation between S. scapterisci's reproduction rate with a bacterial strain and the genetic distance of this bacterial strain from the native one. We also showed that the native bacterium was the only one which was transmitted by S. scapterisci's infective juveniles. All these results, suggested a specialization between S. scapterisci and its native Xenorhabdus. As the same phenomenon was already demonstrated in the association between S. carpocapsae and X. nematophila, specialization between partners would not be an exception in entomopathogenic nematode-bacteria interactions. Nevertheless, S. scapterisci showed a dramatically higher compatibility with non-native Xenorhabdus spp. strains than did S. carpocapsae, suggesting differences in the co-evolutionary processes between nematodes and bacteria in these two model systems.

Steinernema species are entomopathogenic nematodes. They are symbiotically associated with Enterobacteriaceae of the genus Xenorhabdus. These nematode-bacteria symbioses are extremely diversified and constitute an important new model in ecology and evolution to investigate symbioses between microbes and invertebrates. However, no study has so far adequately evaluated either the outcome of the interactions or the obligate nature of interactions in different Steinernema species in the same way. Studying three different species of Steinernema, we showed that symbiotic nematodes are always fitter than aposymbiotic ones. Nevertheless, we revealed contrasting types of interaction in terms of outcome and obligate nature of the interaction. Bacterial analyses showed that nematode species differed dramatically in the number of symbiotic Xenorhabdus they carried. We suggested that when the interaction appeared more facultative for a nematode species, the nematodes carried fewer Xenorhabdus cells than strongly dependent worm species. Thus, the symbiont transmission appeared to become more efficient as the relationship between the nematode and the bacteria became tighter.

Symbioses between invertebrates and prokaryotes are biological systems of particular interest in order to study the evolution of mutualism. The symbioses between the entomopathogenic nematodes Steinernema and their bacterial symbiont Xenorhabdus are very tractable model systems. Previous studies demonstrated (i) a highly specialized relationship between each strain of nematodes and its naturally associated bacterial strain and (ii) that mutualism plays a role in several important life history traits of each partner such as access to insect host resources, dispersal and protection against various biotic and abiotic factors. The goal of the present study was to address the question of the impact of Xenorhabdus symbionts on the progression and outcome of interspecific competition between individuals belonging to different Steinernema species. For this, we monitored experimental interspecific competition between (i) two nematode species: S. carpocapsae and S. scapterisci and (ii) their respective symbionts: X. nematophila and X. innexi within an experimental insect-host (Galleria mellonella). Three conditions of competition between nematodes were tested: (i) infection of insects with aposymbiotic IJs (i.e. without symbiont) of both species (ii) infection of insects with aposymbiotic IJs of both species in presence of variable proportion of their two Xenorhabdus symbionts and (iii) infection of insects with symbiotic IJs (i.e. naturally associated with their symbionts) of both species. We found that both the progression and the outcome of interspecific competition between entomopathogenic nematodes were influenced by their bacterial symbionts. Thus, the results obtained with aposymbiotic nematodes were totally opposite to those obtained with symbiotic nematodes. Moreover, the experimental introduction of different ratios of Xenorhabdus symbionts in the insect-host during competition between Steinernema modified the proportion of each species in the adults and in the global offspring. We showed that Xenorhabdus symbionts modified the competition between their Steinernema associates. This suggests that Xenorhabdus not only provides Steinernema with access to food sources but also furnishes new abilities to deal with biotic parameters such as competitors.

Diplozoon is known to display an exceptional biology of reproduction: the hermaphroditic adults are permanently fused together and their genital ducts communicate. In contrast to all other polyopisthocotylean monogeneans in which the spermatozoa show an homogeneous biflagellate structure, the spermatozoon of Diplozoon is aflagellate. It is filiform, and composed of a cytoplasmic region and a nuclear region. The cytoplasmic region exhibits mitochondria, a well-developed smooth endoplasmic reticulum, and up to 450 longitudinal singlet microtubules. The microtubules show links between them; seen in cross section, they are arranged as rows or polygons. The spermatozoon nuclear region contains the nucleus surrounded by cortical longitudinal microtubules. The spermiogenesis shows no zone of differentiation, a typical structure found in all other parasitic Platyhelminthes. Diplozoon is the first case of aflagellate spermatozoon found in the parasitic Platyhelminthes. The atypical sperm structure is not linked with phylogeny, but is well correlated with the atypical biology of reproduction.