Changes of Super Oxide Dismutase Activity in Hemolymph, Hemocytes and Fat Body of Silkworm (Bombyx mori L.) Challenged by Micrococcus luteus and Escherichia coli

Abstract

The hemolymph, hemocytes and fat body of the silkworm, Bombyx mori L. were determined for superoxide dismutase (SOD) activity following bacteria Micrococcus luteus and Escherichia coli challenged using a photochemical assay system consisting of methionine, riboflavin, and p-nitro blue tetrazolium. The in vitro reduction of nitro blue tetrazolium by superoxide to formazan was measured spectrophotometrically in Bombyx Mori. Hemolymph, hemocytes and fat body were in response to various immune elicitors. We found various tissues and cell-free plasma of silkworm in increased activity of SOD ratio in the one hour and 24 hour (first day) after post inoculation with both bacteria compared with naïve and normal saline-challenged groups. However, SOD activity increased slightly in the hemocytes challenged with Gram −ve bacteria (E. coli) against gram +ve (M. luteus) bacteria. Our results confirm the hypothesis that both Gram +ve and Gram –ve bacterial infection increases the level of oxidative stress in various tissues. In the light of this study, it can be concluded that oxidative damage contributes to cell death in the fat body and hemolymph during bacteriosis.