Macrophage migration inhibitory factor in mud crab Scylla paramamosain: Molecular cloning, expression profiles in various tissues and under Vibrio challenge

As one of the first found cytokines, macrophage migration inhibitory factor (MIF) plays an important role in several physiological processes in crabs. In this study, a full-length MIF cDNA (GenBank accession number: JX131610) from mud crab Scylla paramamosain (Sp) was cloned based on a sequence of S. paramamosain cDNA library. The full length of SpMIF was 734 bp consisting of a 363 bp open reading frame encoding the SpMIF, a 120 amino acid peptide chain. The molecular weight of SpMIF was 13.46 kDa with the pI of 6.82. The alignment analysis showed that SpMIF appeared to be closely related to the counterpart from Eriocheir sinensis (68%). Quantitative real-time PCR analysis revealed that SpMIF was highly expressed in hepatopancreas and hemocytes. In addition, the expression level of SpMIF was increased significantly after a 6-h challenge by Vibrio parahaemolyticus (4.00 × 10⁶ CFU/mL), peaked at 8 h, and then declined to the common level in 48 h. This data indicated that SpMIF was cloned successfully, and suggested that it participated in the immune system of mud crabs.