OCCURRENCE OF BARRED KNIFEJAW, OPLEGNA THUS FASCIA TUS (ACTINOPTERYGII: PERCIFORMES: OPLEGNATHIDAE), IN MALTA (CENTRAL MEDITERRANEAN) WITH A DISCUSSION ON POSSIBLE MODES OF ENTRY

Common carp, Cyprinus carpio, is a model organism within Teleostei. Oligopeptides are a new and promising alternative source of amino acids in animal as well as in human nutrition. In common carp, the membrane protein that transports oligopeptides across the enterocyte membrane is encoded by the gene PepTl (SLC15A1). The aim of this paper was to sequence the PepTl (SLC15A1) in common carp. Materials and Methods. Intestine samples were isolated from six-week old common carp. Total RNA was isolated using a Trizol method. Reverse transcription was used to synthesize cDNA. Two different pairs of primers were designed, according to the zebrafish (Danio rerio) PepTl sequence, and used for PCR. The amplified DNA was isolated by electrophoresis, cloned (pCRII-TOPO vectors), sequenced, and subjected to in silico analysis. Results. Two nucleotide fragments of the PepTl gene were obtained and analyzed using bioinformatic tools. Both fragments showed a high degree of homology with the known PepTl genes of other teleosts, mammals, and birds. High homology of the PepTl gene, and similar primary protein structure among the aforementioned taxa probably reflects the conservative function of the PepTl protein product. Both fragments of the PepTl gene were deposited in GenBank (FJ556590; FJ529670).Conclusions. The sequenced fragments of the common carp PepTl gene will allow evaluation of PepTl expression in the intestines of fish fed diets containing various forms of protein, which is an issue of importance regarding fish nutrition and its import for aquaculture.