Diferencia de eficacia biológica entre fenotipos crípticos relacionados con salinidad en la lubina (Dicentrarchus labrax)

The existence of cryptic salinity-related phenotypes has been hypothesized in the “euryhaline” sea bass (Dicentrarchus labrax). How differential osmoregulation costs between freshwater and saltwater environments affect fitness and phenotypic variation is misunderstood in this species. During an experiment lasting around five months, we investigated changes in the whole body mass and in the expression of growth-related genes (insulin-like growth factor 1 [IGF-1]; growth hormone receptor [GHR]) in the intestine and the liver of sea bass thriving in sea water (SSW), successfully acclimated to freshwater (SFW), and unsuccessfully acclimated to freshwater (UFW). Albeit non-significant, a trend toward change in body mass was demonstrated among SSW, UFW and SFW fish, suggesting that SSW fish were a mixture of the other phenotypes. Several mortality peaks were observed during the experiment, with batches of UFW fish showing higher expression in the osmoregulatory intestine due to down-regulation of genes in the liver and significant up-regulation of GHR in the intestine compared with SFW fish. Energy investment toward growth or ion homeostasis hence partly mediates the fitness difference between cryptic SFW and UFW phenotypes. The use of a genetic marker located within the IGF-1 gene showed no genotype-phenotype relationship with levels of gene expression.En la especie “eurihalina” de la lubina (Dicentrarchus labrax) se ha planteado la existencia de fenotipos crípticos relacionados con la salinidad. En esta especie los costes diferenciales de osmoregulación a la adaptación en de agua dulce y salada son aún desconocidos. Durante un experimento de aproximadamente 5 meses, se investigó los cambios en la masa corporal y en la expresión de genes relacionados con el crecimiento (factor de crecimiento similar a la insulina 1 [IGF-1]; receptor de la hormona del crecimiento [GHR]) en el intestino y el hígado de lubina en individuos que prosperan en agua de mar (SSW), individuos aclimatados con éxito con el agua dulce (SFW), e individuos no aclimatados al agua dulce (UFW). Aunque no es significativa, se observa una tendencia de cambio en la masa corporal entre individuos SSW, UFW y SFW. Estos resultados sugieren que los individuos SSW son una mezcla de los otros fenotipos. Se observaron varios picos de mortalidad durante el experimento, con lotes de peces UFW que presentan una expresión génica más elevada en el intestino osmoregulador, debido a la regulación a la baja de genes en el hígado y regulación hacia arriba en la GHR del intestino cunado se compara con los peces SFW. Por lo tanto, la inversión de energía hacia el crecimiento o la homeostasis iónica explica en parte la diferencia de adaptación entre los crípticos fenotipos SFW y UFW. El uso de un marcador genético localizado dentro del gen de IGF-1 no demuestra relación genotipo-fenotipo con los niveles de expresión génica

Detection of genes influencing economic traits in three French dairy cattle breeds

A project of QTL detection was carried out in the French Holstein, Normande, and Montbéliarde dairy cattle breeds. This granddaughter design included 1 548 artificial insemination bulls distributed in 14 sire families and evaluated after a progeny-test for 24 traits (production, milk composition, persistency, type, fertility, mastitis resistance, and milking ease). These bulls were also genotyped for 169 genetic markers, mostly microsatellites. The QTL were analysed by within-sire linear regression of daughter yield deviations or deregressed proofs on the probability that the son receives one or the other paternal QTL allele, given the marker information. QTL were detected for all traits, including those with a low heritability. One hundred and twenty QTL with a chromosome-wise significance lower than 3% were tabulated. This threshold corresponded to a 15% false discovery rate. Amongst them, 32 were genome-wise significant. Estimates of their contribution to genetic variance ranged from 6 to 40%. Most substitution effects ranged from 0.6 to 1.0 genetic standard deviation. For a given QTL, only 1 to 5 families out of 14 were informative. The confidence intervals of the QTL locations were large and always greater than 20 cM. This experiment confirmed several already published QTL but most of them were original, particularly for non-production traits

Using haematophagous fly blood meals to study the diversity of blood‐borne pathogens infecting wild mammals

Many emerging infectious diseases originate from wild animals, so there is a profound need for surveillance and monitoring of their pathogens. However, the practical difficulty of sample acquisition from wild animals tends to limit the feasibility and effectiveness of such surveys. Xenosurveillance, using blood-feeding invertebrates to obtain tissue samples from wild animals and then detect their pathogens, is a promising method to do so. Here, we describe the use of tsetse fly blood meals to determine (directly through molecular diagnostic and indirectly through serology), the diversity of circulating blood-borne pathogens (including bacteria, viruses and protozoa) in a natural mammalian community of Tanzania. Molecular analyses of captured tsetse flies (182 pools of flies totalizing 1728 flies) revealed that the blood meals obtained came from 18 different vertebrate species including 16 non-human mammals, representing approximately 25% of the large mammal species present in the study area. Molecular diagnostic demonstrated the presence of different protozoa parasites and bacteria of medical and/or veterinary interest. None of the six virus species searched for by molecular methods were detected but an ELISA test detected antibodies against African swine fever virus among warthogs, indicating that the virus had been circulating in the area. Sampling of blood-feeding insects represents an efficient and practical approach to tracking a diversity of pathogens from multiple mammalian species, directly through molecular diagnostic or indirectly through serology, which could readily expand and enhance our understanding of the ecology and evolution of infectious agents and their interactions with their hosts in wild animal communities

Adaptive alien genes are maintained amid a vanishing introgression footprint in a sea squirt

International audienceHuman transport of species across oceans disrupts natural dispersal barriers and facilitates hybridization between previously allopatric species. The recent introduction of the North Pacific sea squirt, Ciona robusta, into the native range of the North Atlantic sea squirt, Ciona intestinalis, is a good example of this outcome. Recent studies have revealed an adaptive introgression in a single chromosomal region from the introduced into the native species. Here, we monitored this adaptive introgression over time, examining both the frequency of adaptive alleles at the core and the hitchhiking footprint in the shoulders of the introgression island by studying a thousand Ciona spp. individuals collected in 22 ports of the contact zone, 14 of which were sampled 20 generations apart. For that purpose, we developed a KASP multiplex genotyping approach, which proved effective in identifying native, nonindigenous and hybrid individuals and in detecting introgressed haplotypes. We found no early generation hybrids in the entire sample, and field observations suggest a decline in the introduced species. At the core region of the introgression sweep, where the frequency of C. robusta alleles is the highest and local adaptation genes must be, we observed stable frequencies of adaptive alien alleles in both space and time. In contrast, we observed erosion of C. robusta ancestry tracts in flanking chromosomal shoulders on the edges of the core, consistent with the second phase of a local sweep and a purge of hitchhiked incompatible mutations. We hypothesize that adaptive introgression may have modified the competition relationships between the native and invasive species in human-altered environments

Falling shoulders ahead: adaptive alien genes maintained amidst vanishing introgression footprint in sea squirts

This zenodo archive contains the multi-locus genotype tables for the paper "Falling shoulders ahead: adaptive alien genes maintained amidst vanishing introgression footprint in sea squirts". There are three files in this archive: Ci_KASP_genotypes_2012.csv: genotype table for individuals sampled in 2012 Ci_KASP_genotypes_2021.csv: genotype table for individuals sampled in 2021 as well as control individuals from the two Ciona species Ci_KASP_genotypes_hybrids.csv: genotype table for control hybrid

Phenotypic and genetic differentiation in young-of-the-year common sole () at differentially contaminated nursery grounds

International audienc

Imprinting along the Kcnq1 domain on mouse chromosome 7 involves repressive histone methylation and recruitment of Polycomb group complexes

International audienc

DNA barcoding post-larvae can improve the knowledge about fish biodiversity: an example from La Reunion, SW Indian Ocean

International audienceThe aim of this study was to demonstrate that fish larvae identified using their COI sequences offer a unique opportunity for improving the knowledge of local fish richness. Fish larvae were sampled at the end of their pelagic phase using light-traps set off the West Coast of La Reunion Island, southwestern Indian Ocean, once per month from October 2014 to March 2015. Among the 5174 larvae caught, 214 morphologically different specimens were selected, 196 successfully barcoded, giving a total of 101 different Barcode Index Numbers (BINs). Among these BINs, 55 had never been recorded in La Reunion exclusive economic zone (EEZ), and 13 were new for the BOLD database. Even if the sampling effort for collecting fish post-larvae during this study was relatively low, it allowed adding at least nine new species to an updated checklist of fishes of La Reunion EEZ

Application of DNA Barcoding for Monitoring Madagascar Fish Biodiversity in Coastal Areas

Madagascar is a marine biodiversity hotspot. A recent checklist recorded 1689 marine or transitional water fish species, 2.5% being endemic. To date, studies in this country were mostly focused on adult fishes using morphological-based identification. The early life stages of fishes remain largely understudied. The present work aimed to improve knowledge of fish biodiversity in Madagascar by focusing on post-larval reef fishes and settled juveniles in seagrass meadows of southwest Madagascar by using either species identification keys or DNA barcoding. Up to 119,500 individuals were collected, and 1096 individuals were successfully barcoded. We identified 387 species—85 through their morphology (with 58 unsuccessfully sequenced) and 302 by using CO1 barcoding corresponding to 302 barcode index numbers (BINs). This study added 27 new BINs for the BOLD database, 120 new for Madagascar, but only 159 were assigned a precise species name. By referring to the updated checklist of Madagascar fishes, 10 new species were detected for Madagascar. This number will probably increase when all the barcoded specimens become assigned to precise species names. These preliminary findings stress our poor knowledge of marine fish biodiversity in Madagascar and demonstrate the relevance of DNA barcoding in improving this knowledg