Diversity
The penaeidins, initially characterized from the shrimp L. vannamei, appear to be a family of antimicrobial peptides ubiquitous among penaeid shrimp. Indeed, recent studies based on genomic approaches have revealed the presence of penaeidins in different penaeid shrimp species. To date, penaeidin sequences have been described in :
All these peptides share high sequence similarities that have allowed the establishment of a penaeidin signature. Moreover, in both L. vannamei and L. setiferus, the three penaeidin sub-groups have been shown to be expressed in one single individual (Cuthbertson et al., 2002), suggesting that the various penaeidins may have different biological functions in shrimp. Expressed sequence tag (EST) analysis from hemocyte cDNA librairies has also revealed the great abundance of penaeidin transcripts found in the shrimps. Penaeidins represent 10.7 and 20%, of all the sequences isolated in both shrimp species, L. vannamei and L. setiferus, respectively. Finally, as shown by biochemical approach, the penaeidin-3 sub-group (PEN3) is dramatically the most abundantly produced. It represents more than 90% of all the penaeidin mRNA sequences detected in both shrimp species (Cuthbertson et al., 2002)
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