Glutathione S-transferase and metallothionein levels in the freshwater prawn Macrobrachium malcolmsonii exposed to mercury.
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Date
2012-01
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Abstract
Healthy juveniles of M. malcolmsonii were exposed to 24.1 <g l-1 of mercury (96 hr LC50: 145 <g l-1 Hg) for a
period of 21 days. The hepatopancreas and gills of the prawns were sampled on 8th, 15th and 22nd day of
exposure. Accumulation and elimination of Hg, activity of glutathione S-transferase (GST), content of glutathione
(GSH) and metallothionein (MT) level were studied. Mercury accumulation was found to be higher in the
hepatopancreas (88.60 <g g-1) and lower in the gills (67.8 <g g-1). However, Hg elimination was found to be faster
in the gills (62%) and slower in the hepatopancreas (58%). Therefore, the rate of Hg elimination did not match the
rate of its uptake. The activity of GST was found to be higher in tissues of test prawns (5.94-9.13 nmol mg-1 protein
min-1) on all sampling days when compared with controls (3.45-4.23 nmol mg-1 protein min-1). Similarly, the content
of GSH was found to be higher in tissues of test prawns (0.80-1.43 <mol g-1 protein) on all sampling days when
compared with controls (0.55-1.00 <mol g-1 protein). These results indicate the formation of glutathione conjugate
in test prawns to eliminate Hg. The induction of MT level was also found to be higher in tissues of test prawns
(57.50-75.76 nmol g-1 protein) on all sampling days when compared with control (20.24-45.22 nmol g-1 protein).
This indicates the fact that sequestration of Hg has occurred for its easy elimination. Thus, induction of GST-GSH
and MT ensured protection and adaptation of test prawns to thrive in Hg contaminated environment.
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Keywords
Prawn, Mercury, Glutathione S-transferase, Reduced glutathione, Metallothionein
Citation
Yamuna A, Bhavan P Saravana, Geraldine P. Glutathione S-transferase and metallothionein levels in the freshwater prawn Macrobrachium malcolmsonii exposed to mercury. Journal of Environmental Biology. 2012 Jan; 33(1): 133-137.