Meeting Abstract
104.4 Thursday, Jan. 7 Characterization of the Bacterial Properties that Impair Respiration in the Atlantic Blue Crab, Callinectes sapidus JOHNSON, N.G.*; BURNETT, L.E.; BURNETT, K.G.; College of Charleston; College of Charleston; College of Charleston ngjohnso@edisto.cofc.edu
In the blue crab Callinectes sapidus, injection with the bacterial pathogen Vibrio campbellii causes a decrease in oxygen consumption. Histological and physiological evidence suggests that the physical obstruction of hemolymph flow through the gills, caused by aggregations of bacteria and hemocytes in the gill vasculature, may underlie the decrease in aerobic function associated with bacterial infection. Alternatively, the observed decline in oxygen uptake could be a reflection of hormonal changes known to be induced by bacterial lipopolysaccharide (LPS), a major constituent of the Gram-negative bacterial cell wall. To determine whether generic particles of various sizes and surface charges are sufficient to stimulate immune and metabolic responses in C. sapidus, the effects of different inert microspheres on total hemocyte count (THC), hemolymph glucose, and hemolymph lactate were evaluated. Injection of V. campbellii caused a dramatic decrease in THC (80% decrease at 0.5 h) that persisted for up to 4 h. Large (4 µm diameter) microspheres caused a mild decrease (ca. 30%) in THC at 0.5 h, whereas small (1 µm) microspheres did not. Surface charge did not have any discernible effects. Hemolymph glucose and lactate levels did not change in response to injected bacteria or microspheres. In future studies, C. sapidus will be injected with a variety of other bacteria and purified LPS to further elucidate the microbial elements necessary and/or sufficient to elicit changes in THC, glucose, lactate, and oxygen uptake. In exploring the range of particles capable of inducing changes in these variables, we hope to gain further understanding of the mechanisms responsible for inducing this decrease in aerobic metabolism, and reveal the extent to which this phenomenon may impact naturally infected crabs. (Supported by NSF IBN-0212921)
