Genomic sequences and genetic differentiation at associated tandem repeat markers in growth hormone, somatolactin and insulin-like growth factor-1 genes of the sea bass,Dicentrarchus labrax

Abstract

-The completion of genomic sequences of physiologically important genes frequently reveals non-coding genetic elements such as tandem repeats (micro-and minisatellites) that are often more polymorphic than nearby coding sequences. We obtained the complete genomic sequences of three hormone genes in sea bass Dicentrarchus labrax: growth hormone (dlGH), somatolactin (dlSL) and insulin-like growth factor-1 (dlIGF-1), including 5 -and 3 -untranslated regions. Mini-and microsatellites were discovered in both flanking and intron regions. Some were partially conserved across Perciformes. To assess the usefulness and relevance of these gene-associated markers for understanding population structure, an investigation was made on genetic diversity and differentiation at four of them in (i) five wild populations from the North Sea, the Bay of Biscay and the Western Mediterranean, and (ii) two samples of hatchery-bred individuals from a freshwater-acclimation experiment. Gene and allelic diversities were lower in cultured individuals than in wild ones. Significant genetic differentiation was demonstrated between Bay of Biscay + North Sea and Mediterranean populations (F st > 0.06, p < 0.001), primarily due to dlGH-associated markers. Significant genetic differentiation was also detected among the Atlantic and North Sea samples, but restricted to the locus associated with dlSL. Significant genetic differentiation was also found among experimental individuals before and after a salinity challenge (F st ≈ 0.05, p < 0.001), but was due to dlSL and dlIGF-1 loci. Gene-associated markers proved to be more efficient than formerly used anonymous microsatellite markers in providing a clear picture of genetic differentiation.Key words: Growth hormone / Somatolactin / Insulin-like growth factor-1 / Non-coding regions / European sea bass / Microsatellites / Minisatellites Résumé -Connaître les séquences génomiques de gènes d'importance physiologique permet de déceler des élé-ments génétiques non-codants tels que des répétitions en tandem (micro -et minisatellites), souvent porteurs de davantage de polymorphismes que les séquences codantes voisines. Des séquences génomiques complètes ainsi que celles de leurs régions flanquantes en 5 et 3 sont établies pour trois gènes codants pour des hormones chez le bar, Dicentrarchus labrax : l'hormone de croissance (dlGH), la somatolactine (dlSL) et le facteur de croissance apparenté à l'insuline (dlIGF-1). Ainsi, un mini-et des microsatellites partiellement conservés chez les Perciformes ont été trouvés. Pour évaluer la pertinence de ces marqueurs pour des études de structure génétique des populations, leur diversité et leur différenciation génétiques sont examinées chez (i) cinq populations sauvages de la mer du Nord, du golfe de Gascogne et de la Méditerranée occidentale, ainsi que dans ( Resour. 23, 285-296 (2010) pour le locus associé à dlSL. Enfin, pour les marqueurs associés à dlSL et dlIGF-1, une différenciation génétique significative est mise en évidence entre individus expérim...

Polymorphisms of the growth hormone gene in domesticated red sea bream populations (Pagrus major) based on minisatellite genotypes and nucleotide sequences

“…Similar polymorphisms have been reported by Zhang, Shao, Jiang, Li and Xu (2009) in the Nibea coibor GH gene, but has not been reported in other fish species (Almuly et al, 2005;Ma et al, 2012;Qu er e et al, 2010;Ryyn€ anen & Primmer, 2004;Tian et al, 2014). This 6 bp repeat motif (GAACCA) is dominantly repeated four times, but some individuals have an additional insertion of the repeat.…”

Isolation and characterization of tandem repeat sequences in the growth hormone gene of the red seabream, Pagrus major (Temminck & Schlegel, 1843)

“…(). Tandem repeat sequences located in the 5′‐flanking region and introns are as reported in other fish species (Almuly et al., ; Quéré et al., ). Therefore, the genetic architecture of GH gene is highly conserved in fish species.…”

“…In the present study, we first determined the nucleotide sequence of the GH gene and its 5′‐flanking region of red seabream. The red seabream GH gene is composed of six exons and five introns, the same as other fish species (Agellon et al., ; Male et al., ; Ber and Daniel, ; Devlin, ; Tanaka et al., ; Ohkubo et al., ; Venkatesh and Brenner, ; Almuly et al., ; Quéré et al., ; Kocour and Kohlmann, ; Ma et al., ). The 5′‐flanking region of pmaGH (‐229 bp to ‐1 bp) was highly conserved between red seabream and gilthead seabream GH , and cis ‐elements located in the promoter (proximal 150 bp) were also conserved among the Perciformes when compared with the result of Almuly et al.…”

Candidate gene variation in gilthead sea bream reveals complex spatiotemporal selection patterns between marine and lagoon habitats

“…A particular focus was made on microsatellite markers located close to 2 candidate genes, GH and Prl, that are functionally related to growth and osmoregulatory capacities in fish (Streelman & Kocher 2002, Almuly et al 2008, Quéré et al 2010) and have been previously showed to be involved in habitat-based genetic differentiation in sea bream (Chaoui et al 2012). This latter study suggested that GH and Prl genotypes with varying selective advantage among lagoons impact mortality in juvenile sea breams that spent their first year of life in ecologically contrasted lagoons (i.e.…”