Marker assisted selection for resistance against viral nervous necrosis in European seabass (Dicentrarchus labrax)

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Linkage mapping, comparative genome analysis, and QTL detection for growth in a non-model teleost, the meagre Argyrosomus regius, using ddRAD sequencing

Meagre (Argyrosomus regius), is a benthopelagic species rapidly emerging in aquaculture, due to its low food to biomass conversion rate, good fillet yield and ease of production. Tracing a species genomic background along with describing the genetic basis of important traits can greatly influence both conservation strategies and production perspectives. In this study, we employed ddRAD sequencing of 266 fish from six F1 meagre families, to construct a high-density genetic map comprising 4529 polymorphic SNP markers. The QTL mapping analysis provided a genomic appreciation for the weight trait identifying a statistically significant QTL on linkage group 15 (LG15). The comparative genomics analysis with six teleost species revealed an evolutionarily conserved karyotype structure. The synteny observed, verified the already well-known fusion events of the three-spine stickleback genome, reinforced the evidence of reduced evolutionary distance of Sciaenids with the Sparidae family, reflected the evolutionary proximity with Dicentrarchus labrax, traced several putative chromosomal rearrangements and a prominent putative fusion event in meagre’s LG17. This study presents novel elements concerning the genome evolutionary history of a non-model teleost species recently adopted in aquaculture, starts to unravel the genetic basis of the species growth-related traits, and provides a high-density genetic map as a tool that can help to further establish meagre as a valuable resource for research and production.info:eu-repo/semantics/publishedVersio

High connectivity of the white seabream (Diplodus sargus, l. 1758) in the aegean sea, eastern mediterranean basin

Population dynamics in the marine realm can shape species’ spatial structure and genetic variability between given geographical areas. Connectivity is an important factor of species’ population structure. In this study, we examined the genetic diversity and structure of white seabream (Diplodus sargus, L. 1758) in the eastern Mediterranean basin, using a panel of four microsatellite markers. Recorded low FST values within the study area indicate little evidence of genetic differentiation among populations. Results suggest high gene flow which may imply near-panmixia between populations, indicating the possibility of a probable movement of adult migrants, or strong passive drift at sea in early life stages of the species. To this extent, bibliographically speaking, different species within the Sparidae family favor altered population dynamics patterns with respect to local populations and genetic divergence, in the context of the molecular marker used. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

Mapping quantitative trait loci in European sea bass (<i>Dicentrarchus labrax</i>): The BASSMAP pilot study

There are great opportunities for genetic improvement in recently domesticated aquaculture species. However, the lack of appropriate tools limits the application of advanced techniques including the mapping of quantitative trait loci (QTL) and marker-assisted selection (MAS). The recent development of a genetic linkage map for the European sea bass allows the application of such methods for the first time in this species. We report a pilot trial of QTL mapping in a commercial sea bass population as a precursor to the application of MAS. Fertilized eggs collected on a single spawning day produced a population composed of a few large families. Fish were grown under commercial conditions, slaughtered at approximately 470 g and measurements were taken for several traits. Parentage analysis showed that the population consisted of 26 full sib families, with a common dam and several sires. Seven microsatellite markers spanning the largest linkage group (LG1) were then genotyped in 27 parents and their 422 progeny, in order to perform a QTL scan using half-sib interval mapping approaches. Significant QTL affecting six morphometric traits including length and depth, are reported. The success of the procedure demonstrates that QTL analysis can be applied in this species and will contribute to the study and future improvement of traits associated with production, profitability and sustainability

Eleven new microsatellites of the sea bass (<i>Dicentrarchus labrax</i> L.)

Eleven polymorphic microsatellites were isolated from the sea bass, Dicentrarchus labrax, using a microsatellite enrichment protocol and selective hybridization with an (AC)12 probe. The loci showed different variation patterns in 21 unrelated sea bass individuals, with a mean number of alleles of 8.6 and a mean observed heterozygosity of 0.68. These microsatellite markers should be useful for population genetic analysis and biodiversity studies of sea bass

Eleven new microsatellites of the sea bass (<i>Dicentrarchus labrax</i> L.)

Eleven polymorphic microsatellites were isolated from the sea bass, Dicentrarchus labrax, using a microsatellite enrichment protocol and selective hybridization with an (AC)12 probe. The loci showed different variation patterns in 21 unrelated sea bass individuals, with a mean number of alleles of 8.6 and a mean observed heterozygosity of 0.68. These microsatellite markers should be useful for population genetic analysis and biodiversity studies of sea bass

A combined AFLP and microsatellite linkage map and pilot comparative genomic analysis of European sea bass <i>Dicentrarchus labrax</i> L.

European sea bass (Dicentrarchus labrax L., Moronidae, Teleostei) sustains a regional fishery and is commonly farmed in the Mediterranean basin, but has not undergone much long-term genetic improvement. An updated genetic linkage map of the European sea bass was constructed using 190 microsatellites, 176 amplified fragment length polymorphisms and two single nucleotide polymorphisms. From the 45 new microsatellite markers (including 31 type I markers) reported in this study, 28 were mapped. A total of 368 markers were assembled into 35 linkage groups. Among these markers, 28 represented type I (coding) markers, including those located within the peptide Y, SOX10, PXN1, ERA and TCRB genes (linkage groups 1, 7, 16, 17 and 27 respectively). The sex-averaged map spanned 1373.1 centimorgans (cM) of the genome. The female map measured 1380.0 cM, whereas the male map measured 1046.9 cM, leading to a female-to-male (F:M) recombination rate ratio of 1.32:1. The intermarker spacing of the second-generation linkage map of the European sea bass was 3.67 cM, which is smaller than that of the first-generation linkage map (5.03 cM). Comparative mapping of microsatellite flanking regions was performed with five model teleosts and this revealed a high percentage (33.6%) of evolutionarily conserved regions with the three-spined stickleback