Meeting Abstract
P2.31 Wednesday, Jan. 5 Bacterial infection in the Dungenness crab, Cancer magister NYERGES, G.; DUNN, S.E.*; PRAMUK, H.E.; SCHOLNICK, D.A.; Pacific University, Forest Grove; Pacific University, Forest Grove; Pacific University, Forest Grove; Pacific University, Forest Grove nyerges@pacificu.edu
The health of the marine environment is deteriorating, coastal regions show increasing signs of pollution and bacteria. Our previous work showed that the Dungeness crab maintains low levels of a Psychrobacter strain in the hemolymph. In the current study we determined the presence of bacteria in the hemolymph from 75 crabs sampled during the summer months of 2010. The level of infection and the strain of bacteria present were identified. Bacteria were isolated from the majority of crabs sampled (between 68 and 84%). The infection level was assessed by plate counting method and showed a considerable range: 0-28760 CFU/ml. The identity of the isolates was determined from 16S rDNA sequence. Psychrobacter was the most prevalent strain, although we obtained 7 other isolates by traditional culturing methods (tryptic soy agar with 5% NaCl and marine agar), and the presence of an unculturable strain was shown by molecular methods. In order to test the effect of bacteria in the hemolymph, crabs were injected with buffered saline (control) or buffered saline with isolated Psychrobacter or Bacillus YT0027 (2.5 X 104 g-1 body weight). The change in hemocyte number was determined by direct cell count in NBF and total hemolymph cell activity was estimated by mitochondrial enzyme activity using XTT. Hemolymph was sampled before injection and 80 min afterward. Injection of Bacillus YT0027 decreased the number of circulating hemocytes, while Psychrobacter did not affect the hemocyte numbers. Total hemolymph cell activity increased after injection of bacteria. These data demonstrate that the chronic presence of a variety of bacteria in the hemolymph is common in the Dungeness crab and may present a constant challenge for their immune system.
