title: An Expressed Sequence Tag (EST)-enriched genetic map of turbot (Scophthalmus maximus): a useful framework for comparative genomics across model and farmed teleosts.
abstract: BACKGROUND
  The turbot (Scophthalmus maximus) is a relevant species in European aquaculture. The small turbot genome provides a source for genomics strategies to use in order to understand the genetic basis of productive traits, particularly those related to sex, growth and pathogen resistance. Genetic maps represent essential genomic screening tools allowing to localize quantitative trait loci (QTL) and to identify candidate genes through comparative mapping. This information is the backbone to develop marker-assisted selection (MAS) programs in aquaculture. Expressed sequenced tag (EST) resources have largely increased in turbot, thus supplying numerous type I markers suitable for extending the previous linkage map, which was mostly based on anonymous loci. The aim of this study was to construct a higher-resolution turbot genetic map using EST-linked markers, which will turn out to be useful for comparative mapping studies.
  
  
  RESULTS
  A consensus gene-enriched genetic map of the turbot was constructed using 463 SNP and microsatellite markers in nine reference families. This map contains 438 markers, 180 EST-linked, clustered at 24 linkage groups. Linkage and comparative genomics evidences suggested additional linkage group fusions toward the consolidation of turbot map according to karyotype information. The linkage map showed a total length of 1402.7 cM with low average intermarker distance (3.7 cM; ~2 Mb). A global 1.6:1 female-to-male recombination frequency (RF) ratio was observed, although largely variable among linkage groups and chromosome regions. Comparative sequence analysis revealed large macrosyntenic patterns against model teleost genomes, significant hits decreasing from stickleback (54%) to zebrafish (20%). Comparative mapping supported particular chromosome rearrangements within Acanthopterygii and aided to assign unallocated markers to specific turbot linkage groups.
  
  
  CONCLUSIONS
  The new gene-enriched high-resolution turbot map represents a useful genomic tool for QTL identification, positional cloning strategies, and future genome assembling. This map showed large synteny conservation against model teleost genomes. Comparative genomics and data mining from landmarks will provide straightforward access to candidate genes, which will be the basis for genetic breeding programs and evolutionary studies in this species.
authors: Departamento de Genética, Facultade de Veterinaria, Universidade de Santiago de Compostela (USC), Campus de Lugo, 27002, Lugo, Spain.
authors: Carmen
authors: C
authors: Bouza
authors: Miguel
authors: M
authors: Hermida
authors: Belén G
authors: BG
authors: Pardo
authors: Manuel
authors: M
authors: Vera
authors: Carlos
authors: C
authors: Fernández
authors: Roberto
authors: R
authors: de la Herrán
authors: Rafael
authors: R
authors: Navajas-Pérez
authors: José Antonio
authors: JA
authors: Álvarez-Dios
authors: Antonio
authors: A
authors: Gómez-Tato
authors: Paulino
authors: P
authors: Martínez
mesh_terms: D000818:Animals; D002874:Chromosome Mapping / Q000379:methods*; D020224:Expressed Sequence Tags; D005260:Female; D005399:Fishes / Q000235:genetics*; D005412:Flatfishes / Q000235:genetics*; D008297:Male; D018895:Microsatellite Repeats; D040641:Quantitative Trait Loci; D026801:Synteny