Carbohydrate dynamics and the crustacean hyperglycemic hormone (CHH): Effects of parasitic infection in Norway lobsters (Nephrops norvegicus)

The effects of a dinoflagellate parasite (Hematodinium sp.) on carbohydrate metabolism were examined in the Norway lobster, Nephrops norvegicus. Five stages of infection were observed. These included uninfected (Stage 0), sub patently infected (SP), and patently infected (Stage 1-4) lobsters. During patent infection, the concentration of glucose in the hemolymph was reduced significantly from its value of 180 mug ml(-1) in uninfected (Stage 0) lob sters to 25.3 mug ml(-1) in Stage 3-4. These changes were accompanied by si gnificantly lower levels of hepatopancreatic glycogen in lobsters at Stage 2 (2.01 mg g(-1)) and Stage 3-4 (0.84 mg g(-1)) of infection than in those at Stage 0 (16.19 mg g(-1)) and Stage 1 (14.71 mg g(-1)). Due to disruption of the normal feedback loops which control the release of crustacean hyper glycemic hormone (CHH), plasma concentrations increased with the severity o f infection from 32.2 fmol ml(-1) in Stage 0 to 106.6 fmol ml(-1) in Stage 3-4. The increased CHH concentrations occurred concomitantly with reduced c oncentrations of plasma glucose and tissue glycogen. A significantly increa sed hemolymph CHH titer (107.7 fmol ml(-1)) was also observed during SP inf ection. It is concluded that the parasite places a heavy metabolic load on the host lobster. (C) 2001 Academic Press.