Project description:We aimed to exemplify early and late transcriptional response of M. galloprovincialis to live Vibrio cells. Hemolymph was collected at 3 and 48 hours after the injection of 10 to 7 cells Vibrio splendidus LGP32 into the posterior adductor muscle. Hemolymph samples were similarly collected from paired control mussels injected with PBS-NaCl. The purified RNAs were successfully amplified, labelled and competitively hybridized to the new mussel oligoarray Immunochip 1.0. After acclimatization, groups of 40 farmed mussels from the Venice lagoon (Italy) were injected either with 10 to 7 cells of Vibrio splendidus LGP32 or with NaCl-enriched PBS. One ml of hemolymph was withdrawn at 3 h and 48 h post-injection from each control or treated mussel. Two RNA pools (N=10) per time point were composed from the treated mussels, processed and competitively hybridized in dye-swap combination (Cy3 / Cy5 aRNAs) on the same Immunochip slide against time-paired control RNA pools (N=40). Since each Immunochip array contains 4 replicates per probe, the dye-swap testing yielded a total of 16 expression values per probe per time-point.
Project description:Vibrio species are recognized for their role in food- and water-borne diseases in humans, fish, and aquatic invertebrates. We screened bacterial strains isolated from raw food shrimp for those that are bactericidal to Vibrio strains. Here we identify and characterize Aeromonas dhakensis strain A603 which shows robust bactericidal activity specifically towards Vibrio and related taxa but less potency toward other Gram-negative species. Using the A603 genome and genetic analysis, we show that two antibacterial mechanisms account for its vibriocidal activity -- a highly potent Type Six Secretion System (T6SS) and biosynthesis of a vibriocidal phenazine-like small molecule, named here as Ad-Phen. Further analysis indicates coregulation between Ad-Phen and a pore-forming T6SS effector TseC, which potentiates V. cholerae to killing by Ad-Phen.