Cloning and expression analysis of farnesoic acid O-methyl transferase(FAMeT)gene during molting in Portunus trituberculatus

To study the regulatory role of farnesoic acid O-methyl transferase(FAMeT)in molting process of crustaceans,the full-length FAMeT cDNA(GenBank accession number:KC192659)of Portunus trituberculatus is cloned by using reverse transcript PCR(RT-PCR)and rapid-amplification of cDNA ends(RACE).FAMeT cDNA contains a 201 bp 5′-untranslated region(5′-UTR),a 318 bp 3′-untranslated region(3′-UTR)and a 825 bp opening reading frame,which encodes 274 amino acid residues.Alignment of deduced amino acid sequence with FAMeT amino acid sequences of other crustaceans revealed that it shares the highest identity with P.pelagicus among the identities ranging from 75% to 97%.The amino acid residues consist of two copies of CF(CPAMD8/FAMeT)domain,which are the hallmark domain of FAMeT and are present in all crustacean FAMeTs.Quantitative real-time PCR(qRT-PCR)was used to quantify the relative expression level of FAMeT in different tissues and at molting stages in P.trituberculatus.The results showed that FAMeT was expressed in various tissues.The mRNA level of FAMeT was the highest in taoracic ganglia,followed by gill and mandibular organ(MO).During the molting process,the expression of FAMeT in MO increased to the maximum at D1 stage,then gradually decreased to the minimum at D4 stage.The results suggest that FAMeT plays an important role in molting regulation in P.trituberculatus.