Archives

Ageing is a universal, biological and natural phenomenon in all living organism. Oxidant damage
by reactive oxygen species along with impaired antioxidant mechanism play a vital role in common
and age related degenerative diseases in animals. To protect molecules against toxic free radicals
and other ROS, cells have developed antioxidant defence system that include the enzymes super
oxide dismutase (SOD), which dismutates toxic superoxide and glutathione peroxidase. Despite of
the absence of glutathione peroxidase (GPx) in insects, the catalase mediates the main mechanism
for hydrogen peroxide (H2O2) breakdown. The natural antioxidant mechanism can be inefficient and
hence dietary intake of anti oxidant compounds become important. In the present study, a reducing
amino acid tryptophan was administered through the feed material of final instar larvae of
silkworm, Bombyx mori, in order to study its antioxidant effects on the growth and longevity of the
larvae. The profiles of pro-oxidant H2O2 and antioxidant enzyme catalase during the development of
the larvae were evaluated. H2O2 levels in haemolymph and fat body of the normal larvae increased
gradually and recorded a peak value at 72h and decreased thereafter. Catalase activity haemolymph
of normal larvae significantly increased from the beginning of fifth instar larval period and recorded
a peak value at 72h followed by a sharp dip.
Key words: Bombyx mori, tryptophan, ageing, H2O2, catalase, ROS