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International audience; Egg production is an economically critical trait in poultry industry. In order to identify genetic markers and chromosomal regions associated with egg production in tropical climate, we conducted both quantitative trait locus (QTL) mapping and genome-wide association study (GWAS) in an F2 cross set up between the Taiwan Country chicken L2 line and an INRA experimental line of Rhode Island Red layer, R-, by using the chicken 60 K SNP chip. A total of eleven QTL (3 genome-wide and 8 chromosome-wide significant QTL) and 102 single nucleotide polymorphism (SNP) effects (7 genome-wide and 95 suggestive significant SNP effects) were identified. Most of detected QTL regions (exclude a QTL on GGA23) and SNPs overlapped with previously published QTL for egg production or quality, providing the evidences to the relationship for the studied traits. The list of QTL and SNPs reported in present study could be contributed to a better comprehension of the genetic control for egg production which is useful for future functional studies.

International audience; Extracellular nucleotides are important mediators of cell activation and trigger multiple responses via membrane receptors known as purinergic receptors (P2). P2X receptors are ligand-gated ion channels, activated by extracellular ATP. P2X4 is one of the most sensitive purinergic receptors, that is typically expressed by neurons, microglia, and some epithelial and endothelial cells. P2X4 mediates neuropathic pain via brain-derived neurotrophic factor and is also involved in inflammation in response to high ATP release. It is therefore involved in multiple inflammatory pathologies as well as neurodegenerative diseases. We have produced monoclonal antibodies (mAb) directed against this important human P2X4 receptor. Focusing on two mAbs, we showed that they also recognize mouse and rat P2X4. We demonstrated that these mAbs can be used in flow cytometry, immunoprecipitation and immunohistochemistry, but not in Western blot assays, indicating that they target conformational epitopes. We also characterised the expression of P2X4 receptor on mouse and human peripheral blood lymphocytes (PBL). We showed that P2X4 is expressed at the surface of several leukocyte cell types, with the highest expression level on eosinophils, making them potentially sensitive to adenosine triphosphate (ATP). P2X4 is expressed by leucocytes, in human and mouse, with a significant gender difference, males having higher surface expression levels than females. Our findings reveal that PBL express significant levels of P2X4 receptor, and suggest an important role of this receptor in leukocyte activation by ATP, particularly in P2X4high expressing eosinophils.

Proliferative kidney disease (PKD) is a widespread disease caused by the endoparasite Tetracapsuloides bryosalmonae (Myxozoa: Malacosporea). Clinical disease, provoked by the proliferation of extrasporogonic parasite stages, is characterized by a chronic kidney pathology with underlying transcriptional changes indicative of altered B cell responses and dysregulated T­helper cell­like activities. Despite the relevance of PKD to European and North American salmonid aquaculture, no studies, to date, have focused on further characterizing the B cell response during the course of this disease. Thus, in this work, we have studied the behavior of diverse B cell populations in rainbow trout (Oncorhynchus mykiss) naturally infected with T. bryosalmonae at different stages of preclinical and clinical disease. Our results show a clear upregulation of all trout immunoglobulins (Igs) (IgM, IgD, and IgT) demonstrated by immunohistochemistry and Western blot analysis, suggesting the alteration of diverse B cell populations that coexist in the infected kidney. Substantial changes in IgM, IgD, and IgT repertoires were also identified throughout the course of the disease further pointing to the involvement of the three Igs in PKD through what appear to be independently regulated mechanisms. Thus, our results provide strong evidence of the involvement of IgD in the humoral response to a specific pathogen for the first time in teleosts. Nevertheless, it was IgT, a fish­specific Ig isotype thought to be specialized in mucosal immunity, which seemed to play a prevailing role in the kidney response to T. bryosalmonae. We found that IgT was the main Ig coating extrasporogonic parasite stages, IgT+ B cells were the main B cell subset that proliferated in the kidney with increasing kidney pathology, and IgT was the Ig for which more significant changes in repertoire were detected. Hence, although our results demonstrate a profound dysregulation of different B cell subsets during PKD, they point to a major involvement of IgT in the immune response to the parasite. These results provide further insights into the pathology of PKD that may facilitate the future development of control strategies., This work was supported by the European Research Council (ERC Consolidator Grant 2016 725061 TEMUBLYM) and the European Commission under the H2020 Programme (Grant H2020-634429 ParaFishControl). IE was recipient of APOSTD/2016/037 grant by the “Generalitat Valenciana” and YH was recipient of a PhD Studentship from the Ministry of Education, Republic of China (Taiwan). JWH was supported by BBSRC grant BB/K009125/1 and SNSF grant CRSII3_147649-1. PDR was funded by grant T1-BIO-1672 from the “Comunidad de Madrid”.