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- Heritability of cortisol response to confinement stress in European sea bass dicentrarchus labraxPublication . Volckaert, F.; Hellemans, Bart; Batargias, C.; Louro, Bruno; Massault, C.; Van Houdt, Jeroen K. J.; Haley, Chris; De Koning, Dirk-Jan; Canario, Adelino V. M.In fish, the most studied production traits in terms of heritability are body weight or growth, stress or disease resistance, while heritability of cortisol levels, widely used as a measure of response to stress, is less studied. In this study, we have estimated heritabilities of two growth traits (body weight and length) and of cortisol response to confinement stress in the European sea bass.FindingsThe F1 progeny analysed (n = 922) belonged to a small effective breeding population with contributions from an unbalanced family structure of just 10 males and 2 females. Heritability values ranged from 0.54 (±0.21) for body weight to 0.65 (±0.22) for standard body length and were low for cortisol response i.e. 0.08 (±0.06). Genetic correlations were positive (0.94) between standard body length and body weight and negative between cortisol and body weight and between cortisol and standard body length (−0.60 and −0.55, respectively).ConclusionThis study confirms that in European sea bass, heritability of growth-related traits is high and that selection on such traits has potential. However, heritability of cortisol response to stress is low in European sea bass and since it is known to vary greatly among species, further studies are necessary to understand the reasons for these differences.
- Divergence of duplicate POMC genes in gilthead sea bream Sparus auratusPublication . Cardoso, João; Laiz-Carrión, R.; Louro, Bruno; Silva, Nádia; Canario, Adelino V. M.; Mancera, J. M.; Power, DeborahProopiomelanocorticotrophin (POMC) in vertebrates is produced in the pituitary gland and undergoes post-translational processing to give rise to a range of biologically active peptides. Teleosts possess 2–3 different POMC transcripts which have been proposed to have originated from a whole or partial genome duplication. In the present study 2 transcripts of gilthead sea bream POMC (sbPOMC-a1 and a2) were cloned and characterised. sbPOMC-a1 is expressed principally in the melanotroph cells of the pars intermedia (PI) and sbPOMC-a2 is expressed in the corticotroph cells of the rostral pars distalis and probably also in the PI. The 2 sbPOMC transcripts have a differential tissue distribution in extra-pituitary sites. An appraisal of POMC evolution indicates sbPOMCs belong to one of the two main clades that exist in teleosts and that overall a non conservative process of gene loss occurred in this infraclass.
- CRTAC1 homolog proteins are conserved from cyanobacteria to man and secreted by the teleost fish pituitary glandPublication . Redruello, Begoña; Louro, Bruno; Anjos, Liliana; Silva, Nádia; Greenwell, Roger S.; Canario, Adelino V. M.; Power, DeborahCartilage acidic protein 1 (CRTAC1) gene expression is used as a marker for chondrocyte differentiation instem cell-based tissue engineering. It is also transcribed outside the skeleton where at least two different transcripts are expressed in lung and brain. In the pituitary gland of the teleost fish sea bream Sparus auratus, we have found a transcript with a high degree of sequence identity to CRTAC1 family members but lacking the EGF-like calcium-binding domain encoding sequence of CRTAC1 and designated it as CRTAC2. Database searches revealed many previously unidentified members of the CRTAC1 and CRTAC2 in phylogenetically distant organisms, such as cyanobacteria, bryophyta, lancelets, and diverse representatives of vertebrates. Phylogenetic analyses showed that the genes encoding CRTAC1 and CRTAC2 proteins coexist in teleost fish genomes. Structural prediction analysis identified the N-terminal region of the CRTAC1/CRTAC2 family members as a potential seven-bladed β -propeller structure, closely related to those of integrin α chains and glycosylphosphatidylinositol-specific phospholipase D1 protein families. This relationship is con fi rmed by phylogenetic analysis with the N-terminal domain of sea bream CRTAC2 as the most divergent sequence. Because teleost fi shes are the only phylogenetic group where both CRTAC1 and CRTAC2 genes are present, they occupy a pivotal position in studies of the mechanisms governing the speci fi c expression patterns of each gene/protein subfamily. This will be essential to elucidate their respective biological roles.
- Advances in european sea bass genomics and future perspectivesPublication . Louro, Bruno; Power, Deborah; Canario, Adelino V. M.Only recently available sequenced and annotated teleost fish genomes were restricted to a few model species, none of which were for aquaculture. Application of Marker Assisted Selection for improved production traits had been largely restricted to the salmon industry and genetic and Quantitative Trait Loci (QTL) maps were available for only a few species. With the advent of Next Generatio Sequencing the landscape is rapidly changing and today the genomes of several aquaculture species have been sequenced. The European sea bass, Dicentrarchus labrax, is a good example of a 17 commercially important aquaculture species in Europe for which in the last decade a wealth of genomic resources, including a chromosomal scale genome assembly, physical and linkage maps as well as relevant QTL have been generated. The current challenge is to stimulate the uptake of the resources by the industry so that the full potential of this scientific endeavour can be exploited and produce benefits for producers and the public alike.
- European sea bass genome and its variation provide insights into adaptation to euryhalinity and speciationPublication . Tine, Mbaye; Kuhl, Heiner; Gagnaire, Pierre-Alexandre; Louro, Bruno; Desmarais, Erick; Martins, Rute S. T.; Hecht, Jochen; Knaust, Florian; Belkhir, Khalid; Klages, Sven; Dieterich, Roland; Stueber, Kurt; Piferrer, Francesc; Guinand, Bruno; Bierne, Nicolas; Volckaert, Filip A. M.; Bargelloni, Luca; Power, Deborah M.; Bonhomme, Francois; Canario, Adelino V. M.; Reinhardt, RichardThe European sea bass (Dicentrarchus labrax) is a temperate-zone euryhaline teleost of prime importance for aquaculture and fisheries. This species is subdivided into two naturally hybridizing lineages, one inhabiting the north-eastern Atlantic Ocean and the other the Mediterranean and Black seas. Here we provide a high-quality chromosome-scale assembly of its genome that shows a high degree of synteny with the more highly derived teleosts. We find expansions of gene families specifically associated with ion and water regulation, highlighting adaptation to variation in salinity. We further generate a genome-wide variation map through RAD-sequencing of Atlantic and Mediterranean populations. We show that variation in local recombination rates strongly influences the genomic landscape of diversity within and differentiation between lineages. Comparing predictions of alternative demographic models to the joint allele-frequency spectrum indicates that genomic islands of differentiation between sea bass lineages were generated by varying rates of introgression across the genome following a period of geographical isolation.