Mussels are filter-feeders living in a bacteria-rich environment.We have previously found that numerous bacterial species are naturally present within the cell-free hemolymph, including several of the Vibriogenus, whereas the intra-cellular content of hemocytes was sterile. When bacteria were injected into the circulation of the mussel, the number of living intra-hemocyte bacteria dramatically increased in less than an hour, suggesting intense phagocytosis, then gradually decreased, with no viable bacteriaremaining 12 h post-injection for micrococcus lysodeikticus, 24 h for Vibrio splendidus and more than 48 h for Vibrio anguillarum. The total hemocyte count (THC) was dramatically lowered by the bacterialinjections, as quantified by flow cytometry. V. splendidus induced the strongest decreases with -66% 9 hpost-injection of living bacteria and -56% 3 h post-injection of heat-killed bacteria. Flow cytometry wasused to identify three main sub-populations of hemocytes, namely hyalinocytes, small granulocytes and large granulocytes. When THC was minimal, i.e. within the first 9 h post-injection, proportions of thethree cell categories varied dramatically, suggesting differential involvement according to the targets, but small granulocytes remained the majority. According to a decrease in their number followed by an increase (+90% at 12 h with living V. splendidus), hyalinocytes also appeared to be involved as cellulareffectors of antibacterial immunity, despite possessing little capacity for phagocytosis and not containing antimicrobial peptides.
|Numero di pagine||7|
|Rivista||Fish and Shellfish Immunology|
|Stato di pubblicazione||Published - 2008|
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