Molecular cloning and gene expression analysis in aquaculture science: a review focusing on respiration and immune responses in European sea bass (Dicentrarchus labrax).

Although fish farming has been practiced for 4,000 years, aquaculture research dates back only to about 1,870, whereas molecular techniques, in addition to the more traditional methods of biotechnology, were introduced only recently. Contemporary genomic approaches (often adapted from human or medical research) such as cDNA cloning and sequencing, cDNA microarray/expression analysis, and functional genomics, combined with improvements in transgenic technologies, have enhanced possibilities for aquacultural biotechnologists for improving fish growth rates and increasing resistance to pathogens and stressors. Although genomic technologies in fish have been applied primarily to model organisms, such as zebrafish (Danio rerio), fugu or pufferfish (Tetraodon nigroviridis), and medaka (Oryzias latipes), many teleosts of interest for biological research and with potential application in aquaculture have unique physiological characteristics that cannot be directly investigated from the study of small laboratory fish models. As a consequence, large-scale genomic research studies are increasingly being applied to farmed species of economic relevance, such as farmed rainbow trout, Atlantic salmon, tilapia, catfish, and sea bass. Accordingly, we describe the utilization of molecular cloning and gene expression analysis in cultured European sea bass (Dicentrarchus labrax) to generate "transcriptome-focused" information which may enable a better understanding of the transcriptional programs that underlie fish respiratory physiology and immune response pathways.