Shp-2 is dispensable for establishing T cell exhaustion and for PD-1 signaling in vivo

In chronic infection and cancer, T cells acquire a dysfunctional state characterized by the expression of inhibitory receptors. In vitro studies implicated the phosphatase Shp-2 downstream of these receptors, including PD-1. However, whether Shp-2 is responsible in vivo for such dysfunctional responses remains elusive. To address this, we generated T cell- specific Shp-2-deficient mice. These mice did not show differences in controlling chronic viral infections. In this context, Shp-2-deleted CD8+ T lymphocytes expanded moderately better but were less polyfunctional than control cells. Mice with Shp-2-deficient T cells also showed no significant improvement in controlling immunogenic tumors and responded similarly to controls to α-PD-1 treatment. We therefore showed that Shp-2 is dispensable in T cells for globally establishing exhaustion and for PD-1 signaling in vivo. These results reveal the existence of redundant mechanisms downstream of inhibitory receptors and represent the foundation for defining these relevant molecular events

Interactions multipolaires entre coléoptères, acariens et diptères (stratégies de dispersion pour l'utilisation de ressources trophiques éphémères)

La phorésie est le mode de dispersion des organismes peu mobiles qui utilisent des transporteurs. Notre travail porte sur l étude des mécanismes qui régissent la phorésie entre trois partenaires : coléoptères Scarabaeidae diptères Sphaeroceridae acariens Macrochelidae. La diversité des interactions hôte-phorétique a été analysée, avec la description de nouvelles espèces d acariens et l étude de deux grandes stratégies de dispersion : généraliste et spécialiste. Le déterminisme de la phorésie nécessite une reconnaissance fine de l hôte par les phorétiques, avec un choix qui se porte sur une partie seulement des hôtes potentiels disponibles, et une tendance à la spécialisation qui a probablement favorisé la spéciation. Des expérimentations en laboratoire (tests comportementaux et olfactométriques) et des analyses chromatographiques ont été conduites pour faire la part des stimuli visuels et chimiques (composés cuticulaires) dans la discrimination des transporteurs. Les acariens choisissent leur hôte en se basant sur des critères chimiques, les diptères sur des critères visuels. Les scarabées transportent leurs phorétiques jusque dans leur nid pédotrophique où l acarien régule les effectifs du diptère phorétique en exerçant une prédation sur ses œufs et larves, avec en réaction un raccourcissement de la durée du cycle du diptère par rapport à d autres diptères coprophiles. Une analyse des affinités entre les différentes espèces d acariens Macrochélides, prenant en compte des données morphologiques, moléculaires et comportementales, montre que le choix spécialisé d un transporteur a pu apparaître de manière indépendante dans différentes lignées d acariens.Phoresy is a dispersal mode for inadequately mobile organisms that use carriers. The aim of our work is to study the mechanisms that govern phoresy among three partners: Scarabaeidae beetles Sphaeroceridae flies Macrochelidae mites. The diversity of host-phoretic interactions has been analysed, with descriptions of new mite species and the study of two main dispersal strategies: generalist and specialist. Phoresy determination needs precise recognition of the host by the phoretics, with a choice of potential available carriers, and a tendency to specialization which probably favours speciation. Laboratory experiments (behavioural and olfactometric tests) and chromatographic analyses have been driven to separate visual and chemical stimuli (cuticular products) in carrier discrimination. The host choice is based on chemical criteria for mites, on visual criteria for flies. Dung beetles carry their phoretics to their pedotrophic nest where the mites regulate the number of phoretic flies by predation on eggs and larvae, with, in reaction, a shortening of the fly development length compared to other coprophilous flies. An analysis of different Macrochelid mite species affinity, using morphological, molecular and behavioural data, shows that the specialized choice of a carrier could appear independently in the different mites lineages.MONTPELLIER-BU Lettres (341722103) / SudocSudocFranceF

Identifying host by macrochelids: chemical cues in the host recognition

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No effect on sex Ratio of two antiandrogens (4P nonylphenol-pestanal & 17 a ethynil estradiol) on Acarus siro (Acari)

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Generalist and specialist strategies in macrochelid mites (Acari: Mesostigmata) phoretically associated with dung beetles (Coleoptera: Scarabaeidae)

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À la recherche du paysage englouti des Gorges de la Loire – Création d’une géovisualisation 3D

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Review of the phoretic association between coprophilous insects and Macrochelid mites (Acari: Mesostigmata) in France

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Semiochemicals mediating host-finding behaviour in the phoretic association between Macrocheles saceri (Acari: Mesostigmata) and Scarabaeus species (Coleoptera: Scarabaeidae)

International audiencePhoresy is an interspecific association where mobile organisms ensure small and/or wingless organisms to colonize patchy distributed environment. Macrocheles saceri (Acari: Mesostigmata) is a phoretic mite which specialized on Scarabaeus dung beetles (Coleoptera: Scarabaeidae). Variation for phoretic load and sites for mite fixation on beetle body has been tested according to Scarabaeus species. The number of setae on beetle body cannot explain the observed patterns in mite fixation. Evidence was provided that the semiochemicals of the host cuticle play a kairomonal role in the host finding behaviour of phoretic mites. In addition semiochemicals ensure host discrimination

Géovisualisation 3D du patrimoine englouti des Gorges de la Loire

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Host selection under predation pressure: case of mites and flies both phoretic on the same dung beetle

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