Expression of intracellular retinoic acid-binding protein in Pinctada fucata martensii and correlation between it and carotenoids

ObjectiveEffects of intracellular retinoic acid-binding protein(CRABP) on absorption and metabolism of carotenoid in Pinctada fucata martensii were investigated to lay a foundation for breeding carotenoid-rich strains.MethodIn this study, cDNA full length sequence of PmCRABP was obtained using RACE technology. Expression cha-racters of PmCRABP gene in different tissues and its expression in white and yellow colored adductor muscle were detected by real-time fluorescence quantitative PCR. ResultThe full length of PmCRABP gene was 1778 bp, including 366 bp of open reading frame(ORF), encoded 121 amino acids, a 5'untranslated region(5'UTR) of 125 bp and a 3'UTR of 1287 bp. The molecular weight was 13.51 kD, theoretical isoelectric point(pI) was 5.68, aliphatic index was 62.81 ,instability index was 35.38 and the grand average of hydropathicity (GRAVY) was -0.517. The 5th to the 120th amino acids of the Pm-CRABP protein were the domains of Lipocalin family. Comparative analysis between amino acid sequence of PmCRABP and that of CRABP of other species indicated that, the similarity between PmCRABP and Metapenaeus ensis CRABP was the highest. Expression of PmCRABP gene in hepatopancreas of P. fucata martensii was the highest, and followed by mantle, gill and adductor muscle. There was significant difference between expressions in different tissues (P<0.05, the same beow). Carotenoid contents and PmCRABP gene expression in yellow and white adductor muscles were signifi-cantly different, and there was a significant positive correlation between carotenoid content and PmCRABP expression.ConclusionThe results showed that PmCRABP gene is involved in carotenoid metabolism of P. fucata martensii.