Differential distribution and defence involvement of antimicrobial peptides in mussel

In previous papers, we characterised 3 types of 4-kDa, cysteine-rich, catio nic antimicrobial peptides: MGDs (for Mytilus galloprovincialis defensins), mytilins and myticins, which are abundant in the mussel hemocytes. In the present work, me revealed a differential distribution of the cells expressi ng the different genes. In addition, using confocal and electron microscopy , we confirmed that defensins and mytilins were partially located in differ ent sub-types of circulating hemocytes although the peptides can be located in the same cell, and even in the same granule. We also demonstrated that mytilins exert their microbicidal effect within the cells through the proce ss of phagosome-mytilin granule fusion leading to the co-location of ingest ed bacteria and mytilins.