10th Symposium on Cladocera location:Lednice, Czech Republic date:28 September - 3 October 2014
Bacterial infections are a widespread threat for many hosts, but experimental model systems for host-bacterial pathogen interactions are limited to a few species. We here investigated the physiological basis of peculiar phenotypic responses and tried to link it to plausible causative agents of White Bacterial Disease (WBD) of the invertebrate crustacean Daphnia. WBD-infected Daphnia can be easily distinguished phenotypically, given that WBD induces intense color changes of the adipose tissue. WBD is a virulent infection, shows horizontal transmission, develops fast and is supposed to be caused by an intercellular bacterial infection of the adipose tissue of its Daphnia host. DAPI staining unraveled the presence of extra living organisms in WBD-infected versus control Daphnia. Denaturing Gradient Gel Electrophoresis (DGGE) indicated the involvement of the Bacteroidetes genera Flavobacterium and Emticicia in WBD-infected individuals. Fluorescence in situ hybridization (FISH) on sections of infected adipose tissue confirmed the presence of members of the Bacteroidetes. The color changes of the adipose tissue of WBD-infected Daphnia can be linked to oxidized fatty acids in the adipose tissue, which makes this host-pathogen system a valuable experimental model to further investigate the link between fatty acid oxidation and immune responses upon infections.