Cloning, tissue expression of the fatty acid-binding protein (Pt-FABP1) gene, and effects of dietary phospholipid levels on fabp and vitellogenin gene expression in the female swimming crab Portunus trituberculatus

In the present study, the cDNA of fatty acid-binding protein (Pt-FABP1) from the hepatopancreas of swimming crab (Portunus trituberculatus) was cloned by rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of Pt-fabp1 was 730 bp and encoded a 130 amino acids polypeptide that was highly homologous to related genes from other crustacean. Quantitative PCR analysis revealed that Pt-fabp1 expression was detected in various tissues, and the highest expression levels was occurred in the hepatopancreas. The Pt-fabp1 expression levels in the ovary would depend on the stages of ovarian development, and the expression of Pt-fabp1 reached the maximum at the stage IV. The effects of dietary soybean lecithin (SL) on the Pt-fabp1 and vitellogenin (VTG) expression, and steroid hormones levels were investigated. After 16 weeks of feeding, the results showed that the expression level of Pt-fabp1 in hepatopancreas and the content of progesterone (PG) in hemolymph did significantly increase with dietary SL supplementation up to 2% (P < 0.05). Swimming crab fed the diet containing 4% SL had higher hepatopancreas vtg gene expression and the content of 17 β-estradiol (E2) in hemolymph than those fed the control diet (P < 0.05). This study suggested that Pt-FABP may have a positive function in ovary maturation of female swimming crab. Meanwhile, these results not only demonstrated that the gene expression of Pt-fabp1 and vtg in hepatopancreas can be modulated by dietary SL levels, but also clearly supported the hypothesis that the positive effects of dietary SL on the ovarian development of female swimming crab.