Expression of heat shock protein 70 in freshwater prawn Macrobrachium malcolmsonii (H. Milne Edwards) following exposure to Hg and Cu.

Juveniles of freshwater prawn M. malcolmsonii were exposed to 1/6th concentration of LC50 of Hg and Cu for 48 hr. Sampling was done at 1 8, 12, 16, 24, 30, 36, 42 and 48 hr of exposure. Gill and hepatopancreas were dissected and subjected to one-dimensional electrophoresis. Western blotting was employed to determine the relative concentration of heat shock protein, hsp 70 (stress-70) in each sample. In the gill tissue of the prawn that had been exposed to Hg (0.024 mgHg 1(-1)), stress-70 was detected from the 1st hr till the 16th hr of exposure. But in the gills of Cu exposed prawn, synthesis of stress-70 appeared from the 1st hr till the 24th hr. Synthesis of hsp70 was not recorded after the 24th hr in the gills of exposed prawns. Synthesis of stress-70 was also found to be tissue-specific for both metals in this prawn. When the antibody probe raised against stress-70 was used, synthesis of stress-70 was not observed in hepatopancreas of prawns exposed to Hg or Cu, during the entire period of exposure of 48 hr. The expression of stress-70 in M. malcolmsonii following exposure to Hg and Cu is apparently only transient, and also a differential expression of stress-70 between gill and hepatopancreas was observed for both the metals.