The delayed over expression of a number of proteases and stress proteins supports the functional hypothesis. Timing and complexity of the mussel immune response as well as the immunostimulation protocol citation could also explain the progressive AMP down regulation observed in the hemocytes of the Vibrio challenged mussels. The HSPs showed instead opposing expres sion trends with only a couple of probes for small HSPs down regulated at 48 h post challenge. These stress inducible protein chaperons probably support pro survival pathways but their multiple roles and complex expression patterns suggest further study. In the same hemocyte samples, lectin like and fibrinogen like adhesion recognition molecules showed heteroge neous expression trends whereas the frequent up regulation of mussel genes relating to the cell shape and motility points to chemotactic and phagocytic hemocyte behaviour.

The enhanced expression of LITAF and per sistent MIF down regulation in response to the injected bacteria encourage us to search regulatory mussel monokines with new immunostimulation trials and approaches other than DNA microarray testing. The samples tested on the Immunochip exemplify only two temporal stages of the multi step response to a reference dose of live V. splendidus cells. The observed transcriptional changes apparently mark the hemocyte activity against the Vibrio cells with a mounting inflam matory response and a shift towards a more gen eral stress condition. A previous equal treatment of M. galloprovincialis with live V.

splendidus, caused a dramatic increase in living intra hemocyte bacteria in less than an hour, suggestive of intense phagocytosis, and a subsequent gradual decrease with only a few viable bacteria at 24 h post injection. Recruited against active bacteria, the total counts of three distinct hemolymph cells almost halved at 3 h post injection and, after 48 h were still below the normal levels. Full understanding of the complex and dynamic response of M. galloprovincia lis to the bacterial attack requires further study. The great number of deep sea vent mussel transcripts made available during manuscript submission and the launch of a new InterProScan Sequence Search inter face will prob ably speed up the cross species identification and validation of immune related genes of marine bivalves. A partial comparison between Mytibase and the Deep SeaVent database rescued 5,261 annotated protein sequences expressed in both M. galloprovincialis and Bathymodio lus azoricus. New BLASTN queries performed with the MGC transcript sequences significantly modulated at 3 and 48 h in the Vibrio injected mussels against the 75,407 transcript sequences of Bathymodiolus azoricus confirmed Brefeldin_A the robustness of the Mytibase annotations.