Can host body size explain the parasite species richness in tropical freshwater fishes ?

The variability of monogenean gill ectoparasite species richness in 19 West African cyprinid species was analyzed using the following seven predictor variables : host size, number of drainage basins, number of sympatric cyprinid species, host diversity, association with mainland forest, host ecology, and monogenean biological labelling. The size of the host species accounted for 77% of the variation in the number of parasite species per host, and host ecology and additional 8%. Together the effects of host size and host ecology accounted for 85% of the variation in monogenean species richness. This study shows that the deciding factors for explaining monogenean species richness in West African cyprinid fishes are host species size and host ecology. These results were compared with main factors responsible for parasite species richness in fish communities. Other possible explanations of monogenean community structure in West African cyprinids are discussed. (Résumé d'auteur

Une ferme maraîchère biologique viable sans motorisation? Le cas d'une approche holistique inspirée par la permaculture

Dans les pays industrialisés, des initiatives innovantes souhaitent s'inspirer des principes de la permaculture pour concevoir des fermes maraîchères sans recours à la motorisation. Afin de tester dans quelle mesure une telle approche peut permettre la viabilité d'une ferme maraîchère commerciale, nous avons mené une étude de cas sur la ferme biologique du Bec Hellouin en France. Ce travail a montré que ces maraîchers ont développé une démarche holistique afin d'obtenir de hauts niveaux de production sur une petite surface et d'augmenter la valeur ajoutée de cette production. Des estimations basées sur des mesures précises en 2013 et 2014 montrent qu'il est potentiellement possible de générer sur une surface cultivée de 1061 m 2 un revenu net mensuel compris entre 898 € et 1 892 €. Ces résultats varient en fonction des niveaux de production et d'investissements matériels et ont été obtenus avec un travail moyen de 43 h par semaine. De telles performances économiques tendent à montrer que ces initiatives peuvent être viables. Cependant, sur cette petite surface travaillée à la main, les maraîchers ont fait le choix de ne pas cultiver certains légumes de conservation, comme les pommes de terre, qui sont attendus par les consommateurs. Ce constat invite à réfléchir à de possibles coopérations entre maraîchers manuels et motorisés pour répondre à cette demande ou sur le recours à la traction animale

Identifying the Achilles heel of multi-host pathogens : the concept of keystone 'host' species illustrated by Mycobacterium ulcerans transmission

Pathogens that use multiple host species are an increasing public health issue due to their complex transmission, which makes them difficult to mitigate. Here, we explore the possibility of using networks of ecological interactions among potential host species to identify the particular disease-source species to target to break down transmission of such pathogens. We fit a mathematical model on prevalence data of Mycobacterium ulcerans in western Africa and we show that removing the most abundant taxa for this category of pathogen is not an optimal strategy to decrease the transmission of the mycobacterium within aquatic ecosystems. On the contrary, we reveal that the removal of some taxa, especially Oligochaeta worms, can clearly reduce rates of pathogen transmission, and these should be considered as keystone organisms for its transmission because they lead to a substantial reduction in pathogen prevalence regardless of the network topology. Besides their potential application for the understanding of M. ulcerans ecology, we discuss how networks of species interactions can modulate transmission of multi-host pathogens

Sedimentological imprint on subseafloor microbial communities in Western Mediterranean Sea Quaternary sediments

An interdisciplinary study was conducted to evaluate the relationship between geological and paleoenvironmental parameters and the bacterial and archaeal community structure of two contrasting subseafloor sites in the Western Mediterranean Sea (Ligurian Sea and Gulf of Lion). Both depositional environments in this area are well-documented from paleoclimatic and paleooceanographic point of views. Available data sets allowed us to calibrate the investigated cores with reference and dated cores previously collected in the same area, and notably correlated to Quaternary climate variations. DNA-based fingerprints showed that the archaeal diversity was composed by one group, Miscellaneous Crenarchaeotic Group (MCG), within the Gulf of Lion sediments and of nine different lineages (dominated by MCG, South African Gold Mine Euryarchaeotal Group (SAGMEG) and <i>Halobacteria</i>) within the Ligurian Sea sediments. Bacterial molecular diversity at both sites revealed mostly the presence of the classes <i>Alphaproteobacteria</i>, <i>Betaproteobacteria</i> and <i>Gammaproteobacteria</i> within <i>Proteobacteria</i> phylum, and also members of <i>Bacteroidetes</i> phylum. The second most abundant lineages were <i>Actinobacteria</i> and <i>Firmicutes</i> at the Gulf of Lion site and <i>Chloroflexi</i> at the Ligurian Sea site. Various substrates and cultivation conditions allowed us to isolate 75 strains belonging to four lineages: <i>Alpha-</i>, <i>Gammaproteobacteria</i>, <i>Firmicutes</i> and <i>Actinobacteria</i>. In molecular surveys, the <i>Betaproteobacteria</i> group was consistently detected in the Ligurian Sea sediments, characterized by a heterolithic facies with numerous turbidites from a deep-sea <i>levee</i>. Analysis of relative betaproteobacterial abundances and turbidite frequency suggested that the microbial diversity was a result of main climatic changes occurring during the last 20 ka. Statistical direct multivariate canonical correspondence analyses (CCA) showed that the availability of electron acceptors and the quality of electron donors (indicated by age) strongly influenced the community structure. In contrast, within the Gulf of Lion core, characterized by a homogeneous lithological structure of upper-slope environment, most detected groups were <i>Bacteroidetes</i> and, to a lesser extent, <i>Betaproteobacteria</i>. At both site, the detection of <i>Betaproteobacteria</i> coincided with increased terrestrial inputs, as confirmed by the geochemical measurements (Si, Sr, Ti and Ca). In the Gulf of Lion, geochemical parameters were also found to drive microbial community composition. Taken together, our data suggest that the palaeoenvironmental history of erosion and deposition recorded in the Western Mediterranean Sea sediments has left its imprint on the sedimentological context for microbial habitability, and then indirectly on structure and composition of the microbial communities during the late Quaternary

Prioritization of fish communities with a view to conservation and restoration on a large scale European basin, the Loire (France)

The hierarchical organization of important sites for the conservation or the restoration of fish communities is a great challenge for managers, especially because of financial or time constraints. In this perspective, we developed a methodology, which is easy to implement in different locations. Based on the fish assemblage characteristics of the Loire basin (France), we created a synthetic conservation value index including the rarity, the conservation status and the species origin. The relationship between this new synthetic index and the Fish-Based Index allowed us to establish a classification protocol of the sites along the Loire including fish assemblages to be restored or conserved. Sites presenting disturbed fish assemblages, a low rarity index, few threatened species, and a high proportion of non-native species were considered as important for the restoration of fish biodiversity. These sites were found mainly in areas where the assemblages are typical of the bream zone, e.g. with a higher number of eurytopic and limnophilic species. On the contrary, important sites for conservation were defined as having an important conservation potential (high RI, a lot of threatened species, and few nonnatives fish species) and an undisturbed fish assemblage similar to the expected community if habitats are undisturbed. Important sites for conservation were found in the Loire basin’s medium reaches which host assemblages typical for the grayling and the barbell zones, e.g. with a higher number of rheophilic species. The synthetic conservation value index could be adapted and completed with other criteria according to management priorities and capacities

Treatment of primary headache in children: a multicenter hospital-based study in France

The aim of this 6-month, prospective, multicenter study of 398 children and adolescents with primary headaches was to collect data on headache treatment in neuropediatric departments. Treatments were compared before and after consultation. Prior to consultation, the acute treatments that had been prescribed most frequently were paracetamol (82.2% of children) and non-steroidal anti-inflammatory drugs treatment (53.5%); 10.3% had received a prophylactic treatment. No differences in either acute or prophylactic treatment with respect to headache diagnosis were observed. After the neuropediatric consultation, paracetamol was replaced by a non-steroidal anti-inflammatory drug in about three-quarters of cases and by triptan in about one-quarter of cases. The number of children prescribed a prophylactic treatment nearly doubled, whereas there was a 5-fold and 23-fold increase in psychotherapy and relaxation training, respectively, between pre-referral and referral. We conclude that specific treatments were underused for primary headache

International Science Foresight Workshop: Global Challenges and Research Gaps. The Royaumont process.

How scientists might better contribute to SDGs in the land sector? At the invitation of INRAE, a group of high-level international experts delivers a comprehensive and systemic approach

Multi-agent systems in epidemiology: a first step for computational biology in the study of vector-borne disease transmission

<p>Abstract</p> <p>Background</p> <p>Computational biology is often associated with genetic or genomic studies only. However, thanks to the increase of computational resources, computational models are appreciated as useful tools in many other scientific fields. Such modeling systems are particularly relevant for the study of complex systems, like the epidemiology of emerging infectious diseases. So far, mathematical models remain the main tool for the epidemiological and ecological analysis of infectious diseases, with SIR models could be seen as an implicit standard in epidemiology. Unfortunately, these models are based on differential equations and, therefore, can become very rapidly unmanageable due to the too many parameters which need to be taken into consideration. For instance, in the case of zoonotic and vector-borne diseases in wildlife many different potential host species could be involved in the life-cycle of disease transmission, and SIR models might not be the most suitable tool to truly capture the overall disease circulation within that environment. This limitation underlines the necessity to develop a standard spatial model that can cope with the transmission of disease in realistic ecosystems.</p> <p>Results</p> <p>Computational biology may prove to be flexible enough to take into account the natural complexity observed in both natural and man-made ecosystems. In this paper, we propose a new computational model to study the transmission of infectious diseases in a spatially explicit context. We developed a multi-agent system model for vector-borne disease transmission in a realistic spatial environment.</p> <p>Conclusion</p> <p>Here we describe in detail the general behavior of this model that we hope will become a standard reference for the study of vector-borne disease transmission in wildlife. To conclude, we show how this simple model could be easily adapted and modified to be used as a common framework for further research developments in this field.</p