Molecular cloning, tissue distribution and nutritional regulation of a fatty acyl elovl5-like elongase in large yellow croaker, Larimichthys crocea

In this study, the full-length cDNA of fatty acyl elovl5-like elongase was first cloned from large yellow croaker, Larimichthys crocea. The cDNA of elovl5-like was 1551 bp, including a 5'-terminal untranslated region (UTR) of 120 bp, a 3'-terminal UTR of 546 bp and an open reading frame (ORF) of 885 bp encoding a polypeptide of 294 amino acid residues. Sequence comparison showed that the predicted protein revealed a high percentage identity (>80%) with Elovl5 from other marine fish species. Tissue distribution analysis revealed that the elovl5-like was expressed highly in liver, brain and gill, and at much lower levels in stomach, intestine, heart and spleen. Quantity polymerase chain reaction showed that hepatic elovl5-like transcription decreased significantly with the increase in dietary n-3LC-PUFA (P < 0.05). The mRNA levels of elovl5-like in the liver of fish fed diets with 0.15%, 0.60% and 0.98% n-3LC-PUFA were upregulated by 1.77-fold, 1.41-fold and 1.41-fold than that with 2.25% n-3LC-PUFA respectively. No significant differences were observed in the hepatic mRNA levels of elovl5-like in response to the increased ratio of dietary DHA/EPA (P > 0.05). These results demonstrate for the first time the presence and nutritional modulation of elovl5-like cDNA in large yellow croaker. This could contribute to better understanding the process of n-3LC-PUFA biosynthesis in this fish species.