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Effects of Hg and Cu on hemocytes-mediated functions in the prawn, Macrobrachium malcolmsonii
A Yamuna1, P Saravana Bhavan, P Geraldine
1Department of Animal Science, Bharathidasan University, Tiruchirappalli-620 024 Tamilnadu, India.
Abstract:
Sublethal effects of Hg (9.6, 14.5 and 24.1 microg/l) and Cu (60.5, 90.8 and 150.5 microg/l) on the hemocytes-mediated functions in the juveniles of the economically important freshwater prawns, Macrobrachium malcolmsonii were investigated. The population of total hemocytes, percentile phagocytosis and superoxide anion production were found to be increased in test prawns exposed to the lowest sublethal concentration of these two metals in comparison to controls. This indicates the fact that a mechanism of host-defence was in an active state to encounter metal toxicity. The total hemocytes population, percentile phagocytosis and superoxide anion production were found to be decreased in test prawns exposed to intermediate as well as the highest sublethal concentrations of Hg and Cu when compared with controls. This suggests that high concentrations of both Hg and Cu have inhibitory effects on the immune functions of the hemocytes in the prawn, M. malcolmsonii.
Insights
Sublethal mercury (Hg) and copper (Cu) exposure initially boosts prawn immune defenses. However, higher concentrations of these metals impair hemocyte functions in Macrobrachium malcolmsonii, indicating toxicity.
Area of Science:
- Environmental toxicology
- Aquatic toxicology
- Crustacean immunology
Background:
- Hemocytes are crucial for invertebrate immune responses.
- Mercury (Hg) and copper (Cu) are common aquatic pollutants.
- Macrobrachium malcolmsonii is an economically important freshwater prawn species.
Purpose of the Study:
- To investigate the sublethal effects of Hg and Cu on hemocyte-mediated immune functions in M. malcolmsonii juveniles.
- To determine the dose-dependent impact of these metals on immune parameters.
Main Methods:
- Exposure of M. malcolmsonii juveniles to varying sublethal concentrations of Hg and Cu.
- Quantification of total hemocyte count.
- Assessment of phagocytosis.
- Measurement of superoxide anion production.
Main Results:
- Lowest sublethal Hg and Cu concentrations increased total hemocyte count, phagocytosis, and superoxide anion production, suggesting an activated host defense.
- Intermediate and highest sublethal concentrations of Hg and Cu decreased these immune parameters compared to controls.
- Indicates a biphasic response to metal toxicity.
Conclusions:
- Sublethal Hg and Cu exposure exhibits a dose-dependent effect on M. malcolmsonii hemocyte functions.
- Low concentrations may stimulate immune responses, while higher concentrations cause immunosuppression.
- Hg and Cu toxicity can significantly impair the immune system of freshwater prawns, with implications for aquaculture and ecosystem health.