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)

•First report of Δ9-desaturase-like gene from Eriocheir sinensis in crustaceans.•The expression of Δ9-desaturase-like gene in various tissues was investigated.•The effect of dietary lipid levels on the expression of the gene was investigated.•The fish oil diet elicited an increasing effect on the gene compared to the soybean oil diet.

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.