THE APPLICATION OF NEUTRAL RED RETENTION ASSAY TO EVALUATE THE DIFFERENCES IN STRESS RESPONSES TO SEXUAL MATURATION AND SPAWNING BETWEEN DIFFERENT SIZES OF PACIFIC OYSTER, CRASSOSTREA GIGAS (THUNBERG)

Abstract

Abstract Neutral red retention (NRR) assay was used to evaluate the effects of sexual maturation, spawning, and post spawning recovery on lysosomal membrane integrity in hemocytes of two size classes of Pacific oysters. Large (102.23 ± 1.79 mm in height and 24 mo old) and small (52.47 ± 2.08 mm in height and 14 mo old) oysters were divided respectively into two groups: Group H was fed a high quantity of microalgae (approximately 2 × 106 cells mL−1 at a rate of 1.0 L per oyster per day) to enhance gonad development, whereas Group L was fed a low quantity of microalgae (same cell concentrations but at a rate of 0.15 L per oyster per day) to minimize changes in their dry meat weight and NRR time. The results showed that prior to spawning the decrease in lysosomal membrane stability in Group H were negatively correlated with the changes in dry meat weight. After spawning, the dry meat weight reduced to a level that was not significantly different from their initial values on day 0. This indicates that prior t...