Differential expression of amino-acid transporters along the intestine of Mozambique tilapia (Oreochromis mossambicus) and the effect of water salinity and time after feeding

Nutrients are absorbed through transporters located in the brush border of intestinal absorptive epithelial cells. These transporters are complexes of proteins that control the uptake or removal of different compounds through cell and organelle membranes. Ingested proteins are catabolized to short-peptide and amino acids, which are absorbed through specified intestinal transporters. Two key complexes in this process are the B(0)AT (encoded by the SLC6A19 gene) and B-0,B-+ AT (encoded by the SLC3A1 and SLC7A9 genes), that transfer neutral and cationic amino acids. This research was conducted in Mozambique tilapia (Oreochromis mossambicus), with the aim of characterizing the dynamic of their expression along different intestinal sections at different time-points after feeding, in different water salinities. Our results demonstrated the dynamic of gene expression patterns along the intestine, with significant salinity effect on the genes encoding to the B-0,B-+ AT. Differences in expression levels with time after feeding were found in all three genes, with the highest expression observed at 6 h after feeding, in the middle intestine. Some of our results differ from what was expected based on data from mammalian organisms, and with only few previous studies on these transporters in any fish species, this is one of the first steps toward characterization of their regulation in fish. Statement of Relevance: The results can lead to better food utilization. (C) 2016 Elsevier B.V. All rights reserved.