Molecular cloning and characterization of macrophage migration inhibitory factor from small abalone Haliotis diversicolor supertexta.

The macrophage migration inhibitory factor (mif) cDNA and its genome were cloned from small abalone Haliotis diversicolor supertexta. Small abalone mif (samif) was originally identified from an expressed sequence tag (EST) fragment from a normalized cDNA library. It's 5' untranslated region (UTR) was obtained by 5' rapid amplification of cDNA end (RACE) techniques and its genomic DNA was cloned by PCR. The full-length cDNA of samif was of 535 bp, consisting of a 5'-terminal UTR of 49 bp, an open reading frame of 384 bp and a 3'-terminal UTR of 102 bp. The deduced protein was composed of 128 amino acids, with an estimated molecular mass of 14.0 kDa and a predicted pI of 6.90. The full-length samif genomic DNA comprises 3238 bp, containing three exons and two introns. Real time quantitative PCR analysis revealed that samif gene is constitutively expressed in 6 selected tissues, and its expression level in hepatopancreas is higher than that in the other tissues (p < 0.01). Samif expression level in the hepatopancreas at 24 and 48 h after Vibrio parahaemolyticus injection was upregulated significantly (p < 0.01), but there was no significant change after exposure to tributyltin (TBT) (p > 0.05).