Abstract

KINETICS OF CATALASE IN SILKWORM BOMBYX MORI L. INFECTED WITH BEAUVERIA BASSIANA (BALS) VUILL.

Thirupathamma.D* and G. Savithri

Abstract

Gradual reduction of catalase activity was noticed in the three selected tissues viz., integument (0.56 to 0.10 μ moles of H2O2 metabolized/mg protein/min), midgut (0.59 to 0.13 μ moles of H2O2 metabolized/mg protein/min) and silkgland (0.50 to 0.12 μ moles of H2O2 metabolized/mg protein/min) of inoculated 5th instar silkworm Bombyx mori larvae with reference to control in all the three tissues i.e., integument (0.65 to 0.21 μ moles of H2O2 metabolized/mg protein/min), midgut (0.66 to 0.32 μ moles of H2O2 metabolized/mg protein/min) and silkgland (0.52 to 0.43 μ moles of H2O2 metabolized/mg protein/min). The reduction of the enzyme activity may be due to metabolic adjustments of the host organism as a part of the defense mechanism due to invasion of fungal pathogen. The decreased catalase activity in experimental larvae may also envisage the possible damage to peroxisomes in the cell and this might be the probable reason for the decreased catalase activity. Reduced catalase activity may lead to accumulation of H2O2 in the Beauveria bassiana inoculated silkworms, which may lead to the mortality of the larvae as H2O2 is cytotoxic.

Keywords: Bombyx mori, Beauveria bassiana, Catalase activity, Integument, Midgut, Silkgland.