Copper-induced oxidative stress and biomarkers in the postlarvae of Penaeus indicus

The objective of the present research is to study the levels of reactive oxygen species (ROS) and protein carbonyl (PC) and the functional protein levels of metallothioneins (MT) in Penaeus indicus postlarvae (PL) upon sublethal copper exposure and to determine the biomarkers. The PL were exposed to sublethal copper of 0.164 ppm. The experiments were carried out in the laboratory over a period of 30 days with sampling intervals of 24, 48, and 96 h and 10, 20, and 30 days. The present study confirms that high oxidative stress can be induced from 24 h onwards upon sublethal exposure to copper in P. indicus PL. This is evident from the increasing levels of ROS in the exposed PL during both short-term and long-term exposures to sublethal copper. Since variability in metallothionein levels from 24 h through 30 days of experimental period was observed, metallothioneins cannot be regarded as a good biomarker as far as copper toxicity with respect to P. indicus PL is concerned. The effect of copper on protein carbonyl seems to be very rapid and consistent. The results suggest that protein carbonyl in P. indicus PL is significantly induced in a time-dependent manner upon copper exposure even at sublethal dose, and it seems reasonable to support that protein carbonyl could be used as a biomarker to copper toxicity.