Identification and Characterization of Carnitine Palmitoyltransferase 1 (cpt 1) Genes in Nile Tilapia, Oreochromis niloticus

Four cpt 1 genes (cpt 1 alpha 1a, cpt 1 alpha 2a, cpt 1 alpha 2b, and cpt 1 beta) were identified in the Nile tilapia genome. Two transmembrane helix domains (TMH) were identified for Cpt 1 alpha 1a, Cpt 1 alpha 2a, and Cpt 1 beta, while Cpt 1 alpha 2b had only one TMH domain. Evidence was found of conserved gene synteny between cpt 1 genes from Nile tilapia and the cpt 1/CPT 1 genes of zebrafish and human. Phylogenetic analysis showed that Nile tilapia Cpt 1 sequences clustered in distinct clades with their orthologous Cpt 1/CPT 1 from other vertebrates. Nile tilapia cpt 1 alpha 1a, cpt 1 alpha 2a, cpt 1 alpha 2b, and cpt 1 beta contain 18 coding exons encoding polypeptides of 771, 784, 788, and 786 amino acids in length, respectively. The cpt 1 genes were determined in all the tested tissues with varying tissue distribution patterns. These findings suggest that (1) cpt 1 alpha 1a, cpt 1 alpha 2a, and cpt 1 alpha 2b arose in the Nile tilapia genome as a result of the teleost-specific whole-genome duplication; (2) nonfunctionalization is the most likely cause of the loss of cpt 1 alpha 1b in the Nile tilapia genome; (3) the different tissue-specific transcription of cpt 1 alpha 2a and cpt 1 alpha 2b may be either due to the sub- or the neo-functionalization of transcriptional control side.