Molecular characterization of a crustin-like, putative antimicrobial peptide, Fi-crustin, from the Indian white shrimp, Fenneropenaeus indicus.

摘要

Antimicrobial peptides are important innate immune defense, especially in those animals which lack adaptive immunity [1e8]. Due to their small size, amphipathic structure and cationic character they can rapidly diffuse to the point of infection [9], a mechanism that presumably makes it easier to circumvent microbial resistance against the peptides [10]. Besides providing an immediate and broad-spectrum microbicidal activity, AMPs can kill bacteria in micromolar range, are promptly synthesized at low metabolic cost, and are easily stored in large amounts and readily available shortly after an infection [11e13]. Many AMPs show a remarkable specificity for prokaryotes with low toxicity for eukaryotic cells; a phenomenon which has favored their investigation and exploitation as potential new antibiotics [14]. AMP gene expression and distribution are regulated through haemocyte reactions [15]. Transcripts of crustin-encoding genes have also been observed in gills, heart and intestine [16e18] but as these tissues are highly vascularised, it is assumed the transcripts from these organs are due primarily to the haemocytes.