Des outils moléculaires pour caractériser la diversité réelle des thysanoptères en cultures ornementales et faciliter le diagnostic

Ce numéro comprend les articles correspondant aux présentations du Colloque Casdar 2018.National audienceThrips are among the most important pests in greenhouses worldwide because of recurrent outbreaks of both native and invading species. Yet, their biodiversity, distribution and ecology remain still poorly documented, probably because of their small size, the high morphological similarity between taxa and their discretion apart from the outbreak in crops. In this study, we thus developed a so-called DNABarcoding approach coupling, on one side, the sequencing of some molecular markers - e.g. a part of the mitochondrial marker Cytochrome Oxidase I (COI) – and, on the other, the precise examination of some morphological characters. Thanks to a collaborative network, several thousands of samples were hence collected in or around crops and more than 1000 individuals were characterized, making it possible (i) to clarify the actual diversity of thrips in these agroecosystems, ii) to focus on some particular (risky and/or invading) species, iii) to design a fast, simple and low cost molecular diagnostic tool for their identification.Les thrips comptent parmi les ravageurs les plus importants des agrosystèmes serres en raison des attaques récurrentes des espèces indigènes et envahissantes. Pourtant, la biodiversité, la distribution et l'écologie des différentes espèces de thrips sont encore peu documentées. Leur petite taille, la forte similitude morphologique entre les différentes espèces et leur discrétion en dehors des pullulations sur cultures expliquent probablement cette situation. Dans ce travail, nous nous sommes donc intéressés à la diversité des thysanoptères collectés en cultures ornementales en France via une approche de type « DNA-Barcoding » couplant une caractérisation moléculaire basée notamment sur une portion du gène mitochondrial cytochrome oxydase (COI) et une caractérisation précise sur des caractères morphologiques. Grâce à un vaste réseau collaboratif, plus de 1000 échantillons de thrips ont ainsi été échantillonnées parmi lesquels plusieurs centaines ont été caractérisés ce qui nous a permis i) de clarifier la diversité réelle des thrips dans ces agroécosystèmes, ii) de rechercher plus particulièrement certaines espèces spécifiques présentant des risques élevés et/ou nouvelles sur le territoire, iii) concevoir un outil de diagnostic moléculaire rapide, simple et peu coûteux pour leur identification en routine

Landscape connectivity alters the evolution of density-dependent dispersal during pushed range expansions

A bstract As human influence reshapes communities worldwide, many species expand or shift their ranges as a result, with extensive consequences across levels of biological organization. Range expansions can be ranked on a continuum going from pulled dynamics, in which low-density edge populations provide the “fuel” for the advance, to pushed dynamics in which high-density rear populations “push” the expansion forward. While theory suggests that evolution during range expansions could lead pushed expansions to become pulled with time, empirical comparisons of phenotypic divergence in pushed vs. pulled contexts are lacking. In a previous experiment using Trichogramma brassicae wasps as a model, we showed that expansions were more pushed when connectivity was lower. Here we used descendants from these experimental landscapes to look at how the range expansion process and connectivity interact to shape phenotypic evolution. Interestingly, we found no clear and consistent phenotypic shifts, whether along expansion gradients or between reference and low connectivity replicates, when we focused on low-density trait expression. However, we found evidence of changes in density-dependence, in particular regarding dispersal: populations went from positive to negative density-dependent dispersal at the expansion edge, but only when connectivity was high. As positive density-dependent dispersal leads to pushed expansions, our results confirm predictions that evolution during range expansions may lead pushed expansions to become pulled, but add nuance by showing landscape conditions may slow down or cancel this process. This shows we need to jointly consider evolution and landscape context to accurately predict range expansion dynamics and their consequences

Disease patterns and specific trajectories of anti-MDA5-related disease: a multicentre retrospective study of 70 adult patients

International audienceIntroduction This study aimed to provide an updated analysis of the different prognostic trajectories of patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibodies. Methods Among a cohort of 70 patients, baseline characteristics and phenotypes, treatments and outcomes were analyzed. A Cox proportional hazards model was used to identify factors associated with poor outcomes, i.e., death or progressive disease at the last follow-up. Results Among the 70 patients, 45 were women, and 54 were Caucasian. A dermatologic involvement was observed in 58 (83%) patients, including 40 with MDA5 vasculopathy-related skin lesions. Muscular involvement was observed in 39 (56%) patients. Interstitial lung disease (ILD) was observed at baseline in 52 (74%) patients, including 23 (44%) who developed rapidly progressive (RP) ILD. Seven (10%) patients showed thromboembolic complications within the first weeks of diagnosis, and eight (11%) other patients developed a malignancy (4 before the diagnosis of anti-MDA5 disease). Poor outcomes were observed in 28 (40%) patients, including 13 (19%) deaths. Among the 23 patients with RP-ILD, 19 (79%) showed poor outcomes, including 12 (63%) who died. In multivariate analyses, RP-ILD (hazard ratio (HR), 95% CI: 8.24 [3.21–22], p<0.0001), the occurrence of thromboembolic events (HR: 5.22 [1.61–14.77], p=0.008) and the presence of any malignancy (HR: 19.73 [6.67–60], p<0.0001) were the three factors independently associated with poor outcomes. Discussion This new independent cohort confirms the presence of different clinical phenotypes of anti-MDA5 diseases at baseline and the poor prognosis associated with RP-ILD. Thromboembolic events and malignancies were also identified as prognostic factors

Table_1_Disease patterns and specific trajectories of anti-MDA5-related disease: a multicentre retrospective study of 70 adult patients.docx

IntroductionThis study aimed to provide an updated analysis of the different prognostic trajectories of patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibodies.MethodsAmong a cohort of 70 patients, baseline characteristics and phenotypes, treatments and outcomes were analyzed. A Cox proportional hazards model was used to identify factors associated with poor outcomes, i.e., death or progressive disease at the last follow-up.ResultsAmong the 70 patients, 45 were women, and 54 were Caucasian. A dermatologic involvement was observed in 58 (83%) patients, including 40 with MDA5 vasculopathy-related skin lesions. Muscular involvement was observed in 39 (56%) patients. Interstitial lung disease (ILD) was observed at baseline in 52 (74%) patients, including 23 (44%) who developed rapidly progressive (RP) ILD. Seven (10%) patients showed thromboembolic complications within the first weeks of diagnosis, and eight (11%) other patients developed a malignancy (4 before the diagnosis of anti-MDA5 disease). Poor outcomes were observed in 28 (40%) patients, including 13 (19%) deaths. Among the 23 patients with RP-ILD, 19 (79%) showed poor outcomes, including 12 (63%) who died. In multivariate analyses, RP-ILD (hazard ratio (HR), 95% CI: 8.24 [3.21–22], pDiscussionThis new independent cohort confirms the presence of different clinical phenotypes of anti-MDA5 diseases at baseline and the poor prognosis associated with RP-ILD. Thromboembolic events and malignancies were also identified as prognostic factors.</p