Wide-transcriptomic analysis of intestine in Mediterranean fish

Trabajo presentado en el 10º Congreso de la Asociación Ibérica de Endocrinología Comparada (AIEC), celebrado en Castellón (España), del 23 al 25 de septiembre de 2015The intestinal tract of teleosts is involved in water and electrolyte balance, immunity, and endocrine regulation of nutrient availability and metabolism. Hence, gastrointestinal syndromes due to nutritional deficiencies and infectious agents are important causes of low growth performance, poor health or serious mortalities in farmed fish. We presented the current research conducted in our laboratory with gilthead sea bream and European sea bass. Attention is mostly focused on the plasticity at the molecular level of the intestine tract in order to identify/validate new intestine health biomarkers of diagnostic and/or prognostic value. In a first stage, microarray expression profiling of sea bass intestine highlighted almost a constant gene expression profile of middle (MID) and anterior (ANT) intestine segments. Conversely, more than 1,800 genes were differently expressed between posterior (POS) and MID-ANT intestine. Thus, POS intestine emerged as a highly immune-regulated tissue, with also relevance on vitamin B12 and bile acid metabolism (entero-hepatic pathway). The differential expression of different chemosensors along the intestine tract was also evidenced. This issue was further verified in sea bream and more than 5,000 unique genes were differentially expressed across the intestine, although this different expression pattern is especially evident in active feeding periods (summer). Microarray and RNA-seq only revealed minor gene expression changes in fish fed balanced low FM/FO diets and interestingly the use of feed additives is able to reverse most of the observed changes towards the wild phenotype. When season was considered, the number of differentially expressed genes (summer vs winter) was higher than 6,500 genes. The magnitude of the change is even higher than that reported after massive destruction of intestine epithelium in chronically parasitized fish. Likewise, previous studies reflected that the plasticity of the transcriptome of anaerobic and highly oxidative muscle tissues is quite lower in comparison to that of the intestine tract.Peer reviewe