Meeting Abstract
P3.60 Wednesday, Jan. 6 Influence of Hypoxia on Psychrobacter Levels in the Dungeness Crab, Cancer magister SCHOLNICK, David A.; HAYNES, Vena N.*; NYERGES, Gyorgyi; Pacfic University, Oregon; Pacific University, Oregon; Pacific University, Oregon david.scholnick@pacificu.edu
Decreases in environmental oxygen, similar to those experienced by many coastal marine crustaceans, can limit the ability of crabs to respond to indigenous bacteria in the hemolymph and increase the rate of bacterial infection. Male Dungeness crabs, Cancer magister, were collected off of the central Oregon coast and maintained in UV sterilized seawater at 9°C. Innate bacteria was characterized from hemolymph isolated from crabs exposed to either 50 or 100% air-saturated water for 3 h. A partial 16S rDNA sequence (1490 nucleotide), amplified from the isolated bacteria, showed 99% identity to 16S rRNA genes from multiple Psychrobacter strains. In order to test the hypothesis that hypoxia impairs antibacterial defense against Psychrobacter, crabs were injected with buffered saline (control) or buffered saline with isolated Psychrobacter (2.5 X 104 g-1 body weight) following exposure to 3 h of hypoxia or under 100% air saturation conditions. Hemolymph was sampled before injection and at 10, 20, 40 and 80 min afterward. Saline injections produced no change in the bacterial or hemocyte counts under hypoxia or air-saturation. The total number of Psychrobacter, measured as colony forming units (CFU) present per mL of hemolymph, was not significantly different between animals held in hypoxic water when compared to normoxia. Injection of Psychrobacter decreased circulating hemocytes regardless of oxygen levels although the number of hemocytes were significantly higher in hypoxic crabs compared to normoxic (8.2 versus 3.8 million respectively) 80 min after bacterial injection. These data demonstrate that Psychrobacter is present in Dungeness crabs and that low oxygen may limit immune response.
