| 17427930 |
Garcia-Gil De Munoz F, Lanz-Mendoza H, Hernandez-Hernandez FC: Free radical generation during the activation of hemolymph prepared from the homopteran Dactylopius coccus. Arch Insect Biochem Physiol. 2007 May;65(1):20-8.
Superoxide anion (O (-) (2)) and nitric oxide (NO) generation in Dactylopius coccus hemolymph obtained by perfusion and activated with zymosan was studied. Activated hemolymph reduced 3-[4,5 dimethylthiazolil-2]-2,5-diphenyl tetrazolium bromide. This reduction was prevented by superoxide dismutase (SOD) indicating O (-) (2) generation. This activity was dependent on temperature, and hemolymph incubated at 75 degrees C lost its activity. Chromatocytes incubated with zymosan released their content and produced O (-) (2). Activated hemolymph also produced NO and this activity was prevented in the presence of NG-nitro-L-arginine methyl ester, suggesting that nitric oxide synthase (NOS) might be present in D. coccus hemolymph. The probable source of O (-) (2) in the D. coccus hemolymph is the anthraquinone oxidation, since commercial carminic dye produced O (-) (2) during its oxidation by Agaricus bisporus tyrosinase. Gram+ Micrococcus luteus exposed to activated hemolymph were killed in vitro, and addition of NG-nitro-L-arginine methyl ester and D-Mannitol (a hydroxyl radical scavenger) prevented their killing. The cytotoxic effect produced by the activated hemolymph was not observed with the Gram- bacteria Serratia marcescens. These results suggest that D. coccus activated hemolymph generates reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI) that may limit M. luteus growth. |
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