| Summary: | 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 <5% empty vect ors or non-recombinants were detected. Based on estimated turbot genome size: 800 Mb the l ibrary provides 5x coverage. To our knowledge, this is the first reported Scophthalmus maximus BAC library. The library contains 46.080 clones arrayed in 120 384-well microtiter pl ates. To isolate genes related to sex- determination and differentiation we screened the l ibrary using the 4D-PCR method with slight modifications. Several genes and/or markers associated to the main sex-determining region or related with gonad differentiation were i dentified and are being used for their physical mapping using FISH. Since some of them had been previously mapped, they are being useful to establish the correspondence betwee n the cytogenetic and ...
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