Construction of a bac library from turbot, Scophthalmus maximus, and identification of clones containing candidate sex-determinig genes

The turbot ( Scophthalmus maximus ) is a highly appreciated European aquaculture species. As farming of turbot is growing as an aqua culture enterprise, the identification of genetic regions responsible for economically import ant traits might be importance for future aquaculture of turbot. The sex-determining systems of fish appear to be at a primitive stage of evolution and display an amazing diversity, includi ng male heterogametic, female heterogametic, and temperature dependent systems. F emales of this species reach commercial size 4-6 months before than males, thus the interes t of industry in obtaining all-female populations. Neither mitotic nor meiotic chromosome s have shown sex-associated heteromorphisms in turbot, but the main sex determi ning region of turbot was identified after a detailed QTL and marker association analysis. Her e we describe the construction and characterization of a bacterial artificial chromoso me (BAC) library from turbot and the identification of clones containing genes related t o the sex determining region and to the gonadal differentiation process. The BAC library wa s constructed from the genomic DNA of a highly inbred individual using the vector pIndigo BAC536. The large, high-quality inserts showed a size of at least 100 kb and