CLONING, CHARACTERIZATION AND EXPRESSION OF FULL LENGTH CDNA ENCODING ALLATOSTATIN (AST) IN MACROBRACHIUM NIPPONENSE

Allatostatin (AST) is a type of neuropeptide, it is made up of a few to dozens of amino acid. In crustaceans, AST has a significant stimulatory effect on MF synthesis, which involved in moulting and reproduction, so it is suggesting that AST in crustaceans has a positive effect on moulting and reproduction. However, AST gene cloning and expression of crustaceans is rarely reported. To investigate gene cloning and expression of AST cDNA in Macrobrachium nipponense, we cloned AST gene in M. nipponense and used quantitative real-time PCR (qRT-PCR) to detecting the expression of AST gene in various tissues. The cloned AST cDNA was 2995 bp in length containing a 242 bp 5′ untranslated region (UTR), a 647 bp 3′ UTR and a 2106 bp open reading flame (ORF). The ORF encoded a AST precursor polypeptide 701 amino acid residues, which can be hydrolyzed into 35 allatostatins at dibasic cleavage sites. These 35 allatostatins had a C-terminal Y/FXFGL-amide in common, which is the characteristics of A type-AST. On the basis the comparison of the amino acid sequences, five amino acids including Tyr, Ala, Phe, Gly and Leu were considered as conserved amino acids during evolution. According to the phylogenetic tree, the insects and crustaceans were divided into two branches through the comparison between different insect and crustaceans. M. nipponense had a closest relationship with M. rosenbergii. The result of qRT-PCR revealed that AST gene was expressed in all the tested tissues. The tissue' expression levels of AST were in the decreasing order hepatopancreas, intestines, testis, brain, heart, and ovary. Our research on AST gene clone and expression contributes to further researching of the function of AST in M. nipponense.