Molecular characterization, tissue expression of acyl-CoA ∆9-desaturase-like gene, and effects of dietary lipid levels on its expression in the hepatopancreas of the Chinese mitten crab (Eriocheir sinensis)

Abstract Acyl-CoA Δ9-desaturase has important functions in fatty acid metabolism and cell membrane fluidity regulation. In this study, we isolated and characterized the acyl-CoA Δ9-desaturase-like cDNA encoded in Eriocheir sinensis (Chinese mitten crab) from the hepatopancreas by performing rapid-amplification of cDNA ends. To the best of our knowledge, this study is the first to perform this procedure in crustaceans. The full-length cDNA is 2419 bp long and encodes a polypeptide with 347 amino acids that are highly homologous to related genes found in insects. Gene expression analysis (real-time quantitative PCR) revealed that acyl-CoA Δ9-desaturase-like transcripts were widely distributed in various tissues, in which a high expression level was observed in the hepatopancreas. A significantly increasing trend was also observed in the hepatopancreas at the megalopa stage to the maturity stage of the Chinese mitten crab. Acyl-CoA Δ9-desaturase gene expression is regulated by a number of developmental, dietary, hormonal, and environmental factors; thus, we determined the effects of acyl-CoA Δ9-desaturase-like mRNA expression in the hepatopancreas after the crabs were fed with different diets for 168 days. The different diets were as follows: control diet without oil lipids (with 3% basic lipid of the fundamental diets); fish oil diet (FO; with added 3% of the fundamental diets); soybean oil diet (SO; with added 3% of the fundamental diets); and FO/SO diet (1:1; with added 3% of the fundamental diets). Results showed that the FO diet elicited a strong increasing effect on the amount of acyl-CoA Δ9-desaturase-like genes compared with control and SO diets.