P1.148 Wednesday, Jan. 4 Immune Response to Acute Bacterial Exposure in the American Lobster KLINGENSMITH, K/C*; JORGENSEN, D/D; Roanoke College; Roanoke College firstname.lastname@example.org
Bacterial infection in some crustacean arthropods evokes an immune response involving the mobilization of hemocytes that recognize and engulf the bacterial cells. It has been suggested that these hemocytes move to the gills through the circulation where they aggregate in gill hemolymph channels for later removal from the animal. Our experiments were designed to follow the timing of immune response in American lobsters (Homarus americanus) to acute bacterial exposure. Vibrio campbellii cells were suspended in lobster saline so that 2x108 CFU (colony forming units) could be delivered in an injection volume of 0.5 µL/g wet body mass. Injection of bacterial suspension was made directly into the heart to insure rapid circulation. Access to the heart was made through an opening drilled in the carapace and sealed with dental dam. Hemolymph samples were withdrawn from the pericardial sinus at set time points and analyzed to determine bacterial and hemocyte hemolymph concentrations. Lobsters injected with saline alone served as controls. Our data show that nearly 90% of the bacteria are cleared from the hemolymph within 30 min post-injection. Circulating hemocyte concentrations decreased by nearly 2/3 within about 20 min post-injection, doubled within an hour, but returned to pre-injection levels within about 90 min. Our experiments suggest a relatively rapid and effective immune response to bacterial infection in lobsters.