title: Free radical generation during the activation of hemolymph prepared from the homopteran Dactylopius coccus.
abstract: 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.
authors.affiliation: Departamento de Patología Experimental. Centro de Investigación y de Estudios Avanzados. Instituto Politécnico Nacional, México, México.
authors.forename: F
authors.initials: F
authors.lastname: García-Gil De Muñoz
authors.forename: H
authors.initials: H
authors.lastname: Lanz-Mendoza
authors.forename: F C
authors.initials: FC
authors.lastname: Hernández-Hernández
mesh_terms: D000818:Animals; D002329:Carmine / Q000031:analogs & derivatives / Q000378:metabolism; D006430:Hemiptera; D006458:Hemolymph / Q000378:metabolism*; D016982:Micrococcus luteus / Q000187:drug effects; D014442:Monophenol Monooxygenase / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000097:blood* / Q000633:toxicity; D010084:Oxidation-Reduction; D012705:Serratia / Q000187:drug effects; D013482:Superoxide Dismutase; D013481:Superoxides / Q000097:blood* / Q000633:toxicity; D013696:Temperature; D013778:Tetrazolium Salts; D013844:Thiazoles; D018675:Toxicity Tests; D015054:Zymosan
chemical_list: D013778:Tetrazolium Salts; D013844:Thiazoles; D013481:Superoxides; D009569:Nitric Oxide; D015054:Zymosan; D002329:Carmine; D014442:Monophenol Monooxygenase; D013482:Superoxide Dismutase; C022616:thiazolyl blue; D019331:NG-Nitroarginine Methyl Ester