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L'influence du recouvrement végétal des radiers d'une rivière à saumon de Bretagne (le Scorff) sur les préférences d'habitat de son peuplement pisciaire a été étudiée durant deux années consécutives. Sur deux radiers de 600 et 800 m2 fortement végétalisés (plus de 70 % de recouvrement), l'expérimentation in situ a consisté à enlever les macrophytes sur la moitié de la surface de chaque radier (du centre du chenal jusqu'à la rive). Les conséquences mésologiques de l'enlèvement des végétaux ont surtout consisté en une forte augmentation des vitesses de courant (60 % en moyenne) dans les habitats où les végétaux avaient été arrachés. Les résultats des pêches électriques réalisées un mois après l'enlèvement des macrophytes (mois de juin) ont mis en évidence des biomasses et des densités plus faibles dans les habitats sans végétaux. Les mêmes espèces étaient présentes dans les deux types d'habitat, mais les juvéniles de saumon atlantique {Salmo salar L.) étaient en moyenne deux fois plus nombreux dans les habitats sans végétaux (30 ind.100 m2) qu'avec végétaux (15 ind.100 m2). Par contre, les densités de loches (Barbatula barbatula L.) et de vairons (Phoxinus phoxinus L.) étaient en moyenne de 47 ind.100 m2 dans les habitats végétalisés, c'est-à-dire 2 à 4 fois plus fortes que dans les habitats sans végétaux. Les résultats indiquent que le développement saisonnier des macrophytes est un important facteur structurant de l'habitat pisciaire dans les rivières du Massif Armoricain et suggèrent une diminution de la capacité d'accueil des radiers en juvéniles de saumon au printemps lors de la pousse des végétaux.

Ce rapport confirme les critères d'interprétation scalimétrique utilisés pour âger le saumon atlantique en eau douce et en mer à l'aide d'exemples typiques. Il synthétise également les difficultés rencontrées pour la détermination d'âge des populations naturelles et d'élevage en les illustrant à l'aide d'exemples atypiques. Enfin, il propose un certain nombre de recommandations pour permettre une meilleure connaissance des populations de saumon atlantique dans son aire de répartition méridionale.

We present a hierarchical Bayesian model (HBM) for capture-mark-recapture (CMR) data analysis. It aims at estimating the probability of capture (&theta[subi]) and the total population size (N[subi]) in a series of I years i =1,a,I. The HBM assumes that the θ[subi]s and N[subi]s are sampled from a common probability distribution with unknown parameters. It is compared with the model assuming independence between years in the θ[subi]s and N i s (ABM). We show how a transfer of information between years is organized by the HBM. We compare the merits of HBM vs. ABM to estimate the spawning run and smolt run of an Atlantic salmon (Salmo salar) population of the River Oir (France) over a period of 17 years. In the spawners case, yearly data are poorly informative. Consequently, the HBM greatly improves posterior inferences compared with the ABM in terms of dispersion and robustness to the choice of prior. In the smolts case, the HBM does not significantly improve inferences compared with the ABM because data are more informative. We discuss why hierarchical modeling should be recommended in any ecological study where the data are collected on several sampling units that share some common features. [ABSTRACT FROM AUTHOR]

Background: Association of HLA-B27 with spondyloarthritis (SpA) has been known for 50 years, but still remains unexplained. We recently showed that HLA-B27 expressed in wing imaginal disc from HLA-B27/human-β2 microglobulin (hβ2m) transgenic Drosophila deregulated bone morphogenetic protein (BMP) pathway by interacting physically with type I BMP receptor (BMPR1) Saxophone (Sax), leading to crossveinless phenotype., Methods: Genetic interaction was studied between activin/transforming growth factor β (TGFβ) pathway and HLA-B27/hβ2m in transgenic Drosophila wings. The HLA-B27-bound peptidome was characterized in wing imaginal discs. In mesenteric lymph node (mLN) T cells from HLA-B27/hβ2m rat (B27 rat), physical interaction between HLA-B27 and activin receptor-like kinase-2 (ALK2), ALK3 and ALK5 BMPR1s, phosphorylation of small mothers against decapentaplegic (SMADs) and proteins of the non-canonical BMP/TGFβ pathways induced by its ligands, and the transcript level of target genes of the TGFβ pathway, were evaluated., Results: In HLA-B27/hβ2m transgenic Drosophila, inappropriate signalling through the activin/TGFβ pathway, involving Baboon (Babo), the type I activin/TGFβ receptor, contributed to the crossveinless phenotype, in addition to deregulated BMP pathway. We identified peptides bound to HLA-B27 with the canonical binding motif in HLA-B27/hβ2m transgenic Drosophila wing imaginal disc. We demonstrated specific physical interaction, between HLA-B27/hβ2m and mammalian orthologs of Sax and Babo, i.e. ALK2 and ALK5 (i.e. TGFβ receptor I), in the mLN cells from B27 rat. The magnitude of phosphorylation of SMAD2/3 in response to TGFβ1 was increased in T cells from B27 rats, showing evidence for deregulated TGFβ pathway. Accordingly, expression of several target genes of the pathway was increased in T cells from B27 rats, in basal conditions and/or after TGFβ exposure, including Foxp3, Rorc, Runx1 and Maf. Interestingly, Tgfb1 expression was reduced in naive T cells from B27 rats, even premorbid, an observation consistent with a pro-inflammatory pattern., Conclusions: This study shows that HLA-B27 alters the TGFβ pathways in Drosophila and B27 rat. Given the importance of this pathway in CD4 + T cells differentiation and regulation, its disturbance could contribute to the abnormal expansion of pro-inflammatory T helper 17 cells and altered regulatory T cell phenotype observed in B27 rats., (© 2024. The Author(s).)

Objectives: The human leucocyte antigen (HLA)-B27 confers an increased risk of spondyloarthritis (SpA) by unknown mechanism. The objective of this work was to uncover HLA-B27 non-canonical properties that could explain its pathogenicity, using a new Drosophila model., Methods: We produced transgenic Drosophila expressing the SpA-associated HLA-B*27:04 or HLA-B*27:05 subtypes, or the non-associated HLA-B*07:02 allele, alone or in combination with human β2-microglobulin (hβ2m), under tissue-specific drivers. Consequences of transgenes expression in Drosophila were examined and affected pathways were investigated by the genetic interaction experiments. Predictions of the model were further tested in immune cells from patients with SpA., Results: Loss of crossveins in the wings and a reduced eye phenotype were observed after expression of HLA-B*27:04 or HLA-B*27:05 in Drosophila but not in fruit flies expressing the non-associated HLA-B*07:02 allele. These HLA-B27-induced phenotypes required the presence of hβ2m that allowed expression of well-folded HLA-B conformers at the cell surface. Loss of crossveins resulted from a dominant negative effect of HLA-B27 on the type I bone morphogenetic protein (BMP) receptor saxophone (Sax) with which it interacted, resulting in elevated mothers against decapentaplegic (Mad, a Drosophila receptor-mediated Smad) phosphorylation. Likewise, in immune cells from patients with SpA, HLA-B27 specifically interacted with activin receptor-like kinase-2 (ALK2), the mammalian Sax ortholog, at the cell surface and elevated Smad phosphorylation was observed in response to activin A and transforming growth factor β (TGFβ)., Conclusions: Antagonistic interaction of HLA-B27 with ALK2, which exerts inhibitory functions on the TGFβ/BMP signalling pathway at the cross-road between inflammation and ossification, could adequately explain SpA development., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

The epidemiology of tinea capitis has had a remarkable change in the past 20 years. It is important for physicians to realize that most tinea capitis in the United States is caused by Trichophyton tonsurans and that these lesions cannot be diagnosed by the Wood's lamp. Trichophyton tonsurans tinea capitis is frequently misdiagnosed because the lesions mimic such common scalp conditions as dandruff and seborrhea. Further, this organism can cause chronic tinea capitis in women that may become a infectious reservoir for other family members. A negative potassium hydroxide preparation will not rule out infection with T tonsurans and cultures are necessary. Scalp lesions in children should be considered tinea capitis until culturally proved otherwise.