Revue d'écologie - La Terre et la Vie

International audienc

Comparative population biology of fish digenes : The case of 3 Helicometra (Trematoda, Opecoelidae) mesoparasites of marine teleosts in a mediterranean lagoon

International audienceIn the Etang de Thau (Herault, France), three species of Helicometra parasitize in their adult stage the digestive tract of the black goby Gobius niger, the grass goby Zosterisessor ophiocephalus, the grey wrasse Symphodus cinereus, and the common eel Anguilla anguilla (Teleostei). These fish act as definitive hosts in the biological cycle of these platyhelminths. Also H. gobii exists in G. niger, Z. ophiocephalus, S. cinereus and A. anguilla ; H. fasciata is found in G. niger ; and H. pulchella is only found in S. cinereus. In the case of the two gobies and the eel, these three congeneric digenes sometimes coexist in the same infracommunity. Spatio-temporal analysis of these different populations has enabled : 1) detection of seasonal variations in their structure, 2) identification of the relationships between the nature of their specificity and demographic strategy, and 3) the global absence of statistical dependence between the intensities of different species in the same infracommunity to be show. Implications arising from previous research concerning the demographic behaviour of these trematodes in their first intermediate host (mollusc compartment), were taken into account when interpreting structures observed in the definitive hosts. The problems of coexistence between these species, which are taxonomically very close in the same parasite community, and the under-lying speciation mechanisms are discussed in the light of population structuration

Dynamique des populations de monogènes, ectoparasites de téléostéens : stratégies démographiques et implications mathématiques

International audienceThe Platyhelminths, or flatworms, are represented by several thousands of species. This phylum consist of several groups, including the Monogeneans. Principally ectoparasites of aquatic vertebrates, these organisms have been studied since the nineteenth century, but essentially from the taxonomic point of view. The study of their population dynamics stay marginal, despite the ecological or epidemiological interest of this zoological group. The demographical modelling is rare and concern only some Monopisthocotylea, ectoparasites of Teleosteans. The main biomathematical trends are summarized in this paper ; their interest is underlined, but also some of their more serious weaknesses. Using the sea bass (Dicentrarchus labrax)-Diplectanum model, the contribution of our interdisciplinary approach combining closely population biology, mathematics and science computing is emphasized.Les Plathelminthes, ou vers plats, sont représentés par des milliers d'espèces, principalement parasites. Ce sous-embranchement comprend plusieurs classes, dont celle des Monogènes. Majoritairement ectoparasites de vertébrés aquatiques, ces derniers sont connus depuis le 19ème siècle, surtout sous l'angle taxinomique. L'étude de la dynamique de leurs populations reste marginale, malgré l'intérêt écologique et épidémiologique que ce groupe zoologique présente. Les approches prédictives de leur démographie, via la modélisation, sont rares ; elles ne concernent que quelques Monopisthocotylea, ectoparasites de poissons téléostéens. Les principales tendances biomathématiques des travaux déjà réalisés sont résumés ; leur intérêt est souligné, mais aussi certains de leurs défauts. Avec le modèle Bar (Dicentrarchus labrax)-Diplectanum que nous avons tout particulièrement étudié, nous illustrerons comment une recherche interdisciplinaire, associant biologie des populations, mathématique et informatique, peut faire évoluer notre connaissance dans un tel domaine

Ecologie et dynamique des populations de monogènes, ectoparasites de téléostéens marins : approche et contribution montpelliéraines / Ecology and population dynamics of Monogenea, ectoparasites of marine Teleostei : montpellieran approach and contribution

International audienceMonogeneans, a fully-fledged class of the Platyhelminth phylum, are represented by thousands of species, ectoparasites of aquatic vertebrates. Marine Teleosts are parasitized by the greatest number of them. These organisms arouse fundamental as well as applied questions, most of them tackled during the last decades by Louis Euzet and several of its colleagues of Montpellier. A synthesis of these ecological works is presented here, as some recent reflections relative to their population dynamics

The biotope of branchial ectoparasites of fishes : factors of variations in the pattern sea bass - monogeneans

International audienceFor the analysis of functional structure of communities, the ecologists are obliged to extend their investigations to the heterogeneity of their environment and colonized biotopes. The gills of sea bass Dicentrarchus labrax serve as a biotope for several ectoparasites ; some aspects of the heterogeneity of this biotope were studied quantitatively. The models expressing the variations of number of branchial filaments, and branchial area that can be colonized by monogeneans, were established in function of the lenght of fishes. Such biotopes being subjected to significant physical modifications, the effects of the latter over the organization of parasitic settlements are then discussed

Protozoaires et Métazoaires parasites de l'anguille Anguilla anguilla : Interdépendance des populations parasitaires et coexistence des pathogènes potentiels

International audienceA monthly sampling of eels in the mixohalin lagoon of Mauguio (Languedoc, France) allowed the analysis of Anguillicola crassus (Nemathelmintha), Myxidium giardi (Myxozoa) and Eimeria anguillae (Sporozoa) population structures. This study showed that the high intensities of A. crassus, a parasite recently introduced in this area, seem to induce the development of both protists. However, any negative effect of these parasites of Anguilla anguilla can be detected by the study of the host size/weight relation

Myosin-Vb functions as a dynamic tether for peripheral endocytic compartments during transferrin trafficking

<p>Abstract</p> <p>Background</p> <p>Myosin-Vb has been shown to be involved in the recycling of diverse proteins in multiple cell types. Studies on transferrin trafficking in HeLa cells using a dominant-negative myosin-Vb tail fragment suggested that myosin-Vb was required for recycling from perinuclear compartments to the plasma membrane. However, chemical-genetic, dominant-negative experiments, in which myosin-Vb was specifically induced to bind to actin, suggested that the initial hypothesis was incorrect both in its site and mode of myosin-Vb action. Instead, the chemical-genetic data suggested that myosin-Vb functions in the actin-rich periphery as a dynamic tether on peripheral endosomes, retarding transferrin transport to perinuclear compartments.</p> <p>Results</p> <p>In this study, we employed both approaches, with the addition of overexpression of full-length wild-type myosin-Vb and switching the order of myosin-Vb inhibition and transferrin loading, to distinguish between these hypotheses. Overexpression of full-length myosin-Vb produced large peripheral endosomes. Chemical-genetic inhibition of myosin-Vb after loading with transferrin did not prevent movement of transferrin from perinuclear compartments; however, virtually all myosin-Vb-decorated particles, including those moving on microtubules, were halted by the inhibition. Overexpression of the myosin-Vb tail caused a less-peripheral distribution of early endosome antigen-1 (EEA1).</p> <p>Conclusion</p> <p>All results favored the peripheral dynamic tethering hypothesis.</p

Are Small Effects the Indispensable Foundation for a Cumulative Psychological Science? A Reply to Götz et al. (2022).

Götz et al. (2022) argue that small effects are “the indispensable foundation for a cumulative psychological science”. They support their argument by claiming that (i) psychology, like genetics, consists of complex phenomena explained by additive small effects, (ii) psychological research culture rewards large effects, which means small effects are being ignored, and (iii) small effects become meaningful at scale and over time. We rebut these claims with three objections: (i) the analogy between genetics and psychology is misleading, (ii) p-values are the main currency for publication in psychology, meaning that any biases in the literature are (currently) caused by a pressure to publish statistically significant results and not large effects, and (iii) claims regarding small effects as important and consequential must be supported by empirical evidence or, at least, a falsifiable line of reasoning. If accepted uncritically, we believe the arguments of Götz et al. (2022) could be used as a blanket justification for the importance of any and all ‘small’ effects, thereby undermining best practices in effect size interpretation. We end with guidance on evaluating effect sizes in relative, not absolute terms

The Psychological Science Accelerator: Advancing Psychology Through a Distributed Collaborative Network

Source at https://doi.org/10.1177/2515245918797607.Concerns about the veracity of psychological research have been growing. Many findings in psychological science are based on studies with insufficient statistical power and nonrepresentative samples, or may otherwise be limited to specific, ungeneralizable settings or populations. Crowdsourced research, a type of large-scale collaboration in which one or more research projects are conducted across multiple lab sites, offers a pragmatic solution to these and other current methodological challenges. The Psychological Science Accelerator (PSA) is a distributed network of laboratories designed to enable and support crowdsourced research projects. These projects can focus on novel research questions or replicate prior research in large, diverse samples. The PSA’s mission is to accelerate the accumulation of reliable and generalizable evidence in psychological science. Here, we describe the background, structure, principles, procedures, benefits, and challenges of the PSA. In contrast to other crowdsourced research networks, the PSA is ongoing (as opposed to time limited), efficient (in that structures and principles are reused for different projects), decentralized, diverse (in both subjects and researchers), and inclusive (of proposals, contributions, and other relevant input from anyone inside or outside the network). The PSA and other approaches to crowdsourced psychological science will advance understanding of mental processes and behaviors by enabling rigorous research and systematic examination of its generalizability