In vitro generation of superoxide anion by the hemocytes of Macrobrachium rosenbergii: possible mechanism and pathways.
The hemocytes from the giant freshwater prawn Macrobrachium rosenbergii were examined for their ability to generate superoxide anion (O(2) (-)) in vitro upon exposure to various components derived from microbial cell wall components. Among the test molecules, laminarin (a polymer of beta-1, 3 glucans), mannan and LPS from five different bacterial species produced a differential response in terms of stimulated O(2) (-) production in prawn hemocytes, suggesting the ability of the hemocytes to differentiate non-self. This response was almost completely inhibited by superoxide dismutase (SOD) suggesting SOD-inhibitable O(2) (-) generation by prawn hemocytes. Phorbol 12-myristate 13-acetate (PMA) and Ca ionophore led to enhanced O(2) (-) generation by the hemocytes and this suggests the possible role of protein kinase C and Ca(2+) ions in such generation. Cytochemical analysis using nitroblue tetrazolium (NBT)-staining revealed the importance of granular hemocytes in O(2) (-) generation in these prawns. Inhibition of O(2) (-) generation by inhibitors of NADPH-oxidase and phenoloxidase pathways clearly reveal the involvement of two different pathways in non-self stimulated O(2) (-) generation by the prawn hemocytes. These findings demonstrate the importance of O(2) (-) generation and role of possible pathways in hemocyte mediated cellular immune response of a crustacean.
Vidya
Natarajan
N
Laboratory of Pathobiology, Department of Zoology, University of Madras, Guindy Campus, Chennai, India.
Thiagarajan
Raman
R
Arumugam
Munusamy
M
D000818:Animals; D005936:Glucans; D006434:Hemocytes / Q000276:immunology* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology; D008351:Mannans / Q000276:immunology; D009580:Nitroblue Tetrazolium; D033541:Palaemonidae / Q000276:immunology* / Q000378:metabolism; D011134:Polysaccharides / Q000276:immunology; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000037:antagonists & inhibitors / Q000378:metabolism*
D005936:Glucans; D008070:Lipopolysaccharides; D008351:Mannans; D011134:Polysaccharides; D013481:Superoxides; D009580:Nitroblue Tetrazolium; C008247:laminaran; D013482:Superoxide Dismutase