[Molecular cloning and expression of Attacin from housefly (Musca domestica)]

The antimicrobial peptides of insect are the main components of their non-specific immune system, and play a major role in the defense against the foreign disease-related microbes. In this report, a full length cDNA of Attacin, an insect antimicrobial peptide was cloned from housefly (Musca domestica) by homology cloning approach in combine with 3' and 5' RACE. Sequence analysis and phylogenetical study showed that this cDNA contained 778 nucleotides, with a 627 bp open reading frame (ORF) flanked with a 44 bp 5'UTR and a 107 bp 3'UTR. The encoded 208 amino acids housefly Attacin shared a high similarity of 50%-70% with that of the other dipterous insects. In addition, the phylogenetical analysis also indicated that the Attacin from housefly was in the same branch with those of other species, suggesting that they come from the same ancestor. The expression of Attacin transcript was measured by semi-quantitive RT-PCR. The results demonstrated that the expression of housefly Attacin is inducible, and that the level varies with the time of induction and the kinds of pathogens.