Response of haemocyte lysosomes to bacterial inoculation in the oysters Ostrea edulis L. and Crassostrea gigas (Thunberg) and the scallop Pecten maximus (L.)

Data are presented that demonstrate the application of the neutral red rete ntion assay (NRR) to monitor the effects of st bacterial inoculation on the haemocyte lysosomes of the European flat oyster Ostrea edulis, Pacific oys ter Crassostrea gigas and scallop Pecten maximus. Bivalves were acclimated to three temperature regimes (5, 15 and 25 degrees C), at constant salinity for 7 days in the laboratory. Once baseline responses to acclimation tempe rature had been established, the effects of an in vivo inoculation on haemo cyte lysosomal stability were assessed using th NRR assay. Lysosomal membra ne stability was reduced in the presence of bacteria for all three species of bivalve, but destabilisation of C. gigas haemocyte lysosomes appeared to be most sensitive to the presence of the bacterium Listonella anguillarum. For all three bivalve species, the reduction in lysosomal stability appear ed to be proportional to the growth of the bacterial inoculate. Using appro priate controls, the NRR assay was demonstrated to have great potential as a tool with which to make rapid initial assessments of the immune status of bivalve molluscs. (C) 2001 Academic Press.