2000 Volume 35 Issue 3 Pages 109-116
When separate batches of Macrobrachium rosenbergii hemocytes were cultured in different media at 25°C for 40 min, the percentage of viable hemocytes cultured in modified M-199 medium (M-199;80%) was significantly higher than the percentage cultured in modified crayfish saline (M-CFS;65%), although wide individual variation was noted. The percentage of phagocytic cells increased significantly with lipopolysaccharide (LPS) concentrations up to 16μg/mL, but no further significant increases were found at concentrations from 16 to 100μg/mL. Microscopy of phagocytosis in hemocytes cultured in M-199 and induced with LPS at a final concentration of 20μg/mL showed that target zymosan particles (1-4μm) were engulfed by granulocytes (GC) and semigranulocytes (SGC), but were only attached to and not engulfed by hyaline cells (HC). However, smaller sized fluorescent-labeled beads (0.5μm) were primarily phagocytosed by HC. This suggests that all three types of hemocytes from M. rosenbergii are able to phagocytose foreign particles. Microscopy showed that LPS significantly altered hemocyte morphology by increasing pseudopodia stretching and hemocyte size and it also increased the number of engulfed particles per phagocyte. The percentage of HC positive for two lysosomal enzymes (acid phosphatase and α-naphthyl acetate esterase) related to phagocytosis was higher than that of positive SGC or GC.