ENHANCED LEVELS OF METALLOTHIONEIN IN SCYLLA SERRATA EXPOSED TO CADMIUMY. PRABHAKARA RAO', A. SIRISHA AND P.V. RAMANA
Metallothioneins (MTs) are low molecular weight proteins rich in cysteine content and are reported to be present in most of the invertebrates. In the present investigation, experiments were carried out to determine the MT content in hepatopancreas of Scylla serrata exposed to cadmium. The MT content was determined by adopting silver saturation method. Parallel controls were maintained throughout the experiments. Initially, static renewal bioassays were conducted to estimate 96h LC50 value of cadmium and it was observed to be 16.87 ppm (Y=1.6364 + 2.7414X; r=0.9962). Experiments were performed further by exposing the crabs to a sublethal concentration (1/5th of LC,) of cadmium for 10 days. Hepatopancreas was isolated from both control and exposed crabs at intervals of 24h, 48h, 961i and 10 days for MT and metal estimation. The results indicate an increase in MT content in relation to exposure period. Though these investigations suggest enhanced levels of MT on cadmium exposure, further experiments are needed to differentiate various types of MTs.
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