Rama Krishnan Poopal

Short-term mercury exposure on Na+/K+-ATPase activity and ionoregulation in gill and brain of an Indian major carp, Cirrhinus mrigala

Recently mercury pollution has been increased considerably in aquatic resources throughout the world and it is a growing global concern. In this study, the 96 h LC50 value of waterborne mercuric chloride for Cirrhinus mrigala was found to be 0.34 mg/L (with 95% confidence limits). Fingerlings of C. mrigala were exposed to 0.068 and 0.034 mg/L of mercuric chloride for 96 h to assess the Na(+)/K(+)-ATPase activity and ionoregulation (Na(+), K(+) and Cl(-)) in gill and brain. Results showed that Na(+)/K(+)-ATPase activity and ionic levels (Na(+), K(+) and Cl(-)) in gill and brain of fish exposed to different concentrations of mercuric chloride were found to be significantly (p<0.05) decreased throughout the study period. Mercury inactivates many enzymes by attaching to sulfur atoms in which the enzyme Na(+)/K(+)-ATPase is highly sensitive to mercury. The inhibition of gill and brain Na(+)/K(+)-ATPase activity might have resulted from the physicochemical alteration of the membrane due to mercury toxicity. Moreover, inhibition of Na(+)/K(+)-ATPase may affect the ion transport and osmoregulatory function by blocking the transport of substances across the membrane by active transport. The present study indicates that the alterations in these parameters can be used in environmental biomonitoring of mercury contamination in aquatic ecosystem.

Hematological, biochemical and enzymological responses in an Indian major carp Labeo rohita induced by sublethal concentration of waterborne selenite exposure

Selenium (Se) pollution in aquatic ecosystem is an environmental issue throughout the world. Elevated concentrations of inorganic Se from agricultural and industrial processes may cause adverse biological effects in aquatic organisms such as fish. In the present study, Labeo rohita an Indian major carp were exposed to sublethal concentration of Se (sodium selenite) for 35days and certain hematological, biochemical and enzymological parameters were estimated. The median lethal concentration of waterborne sodium selenite (Na2SeO3) to L. rohita was found to be 23.89mgL(-1) for 96h. During sublethal (2.38mgL(-1)) treatment, hematological and biochemical parameters such as hemoglobin (Hb) (except 14th day), hematocrit (Hct), erythrocyte (RBC) count and protein levels were found to be decreased in Se treated fish whereas leucocyte (WBC) count and glucose level increased in Se treated fish throughout the study period. The enzymatic parameters such as glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT) and lactate dehydrogenase (LDH) activities were found to be increased in liver of Se treated fish L. rohita. A biphasic response was observed in the value of mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC). The alterations of these parameters can be used as suitable biomarkers in monitoring of selenium in the aquatic environment and to protect aquatic life.

Bioconcentration of methylmercury in microzooplankton in a temperate river

To understand the bioconcentration of methylmercury (MeHg) at the base of the riverine food chain, we determined levels of dissolved organic carbon, microseston, Hg, and MeHg in surface water in relation to the microzooplankton MeHg from Yeongsan River. The spatial distribution of unfiltered Hg (0.29-3.1 ng/L) and dissolved Hg (0.15-0.74 ng/L) closely followed the microseston distribution. The spatial distribution of unfiltered MeHg (0.0078-0.077 ng/L) and dissolved MeHg (0.0069-0.018 ng/L) increased with increasing distance from the river mouth and appeared to arise from the shallow wetlands surrounding the upper riverbanks and then to be transported downstream. The logarithm of the MeHg bioconcentration factor for microzooplankton ranged from 5.3 to 6.0 (5.7 ± 0.18), and for microseston ranged from 4.0 to 5.4 (4.9 ± 0.35). Linear correlation statistics comparing microzooplankton MeHg and river water characteristics revealed that microzooplankton MeHg concentration was most significantly correlated with unfiltered MeHg (r = 0.83) and particulate MeHg (r = 0.80) levels. This result suggests that MeHg in unfiltered river water, which is relatively easy to determine, can be used as a surrogate for MeHg in microzooplankton that may influence MeHg levels in higher-trophic-level organisms.

Evaluation of acute and sublethal effects of chloroquine (C 18 H 26 CIN 3 ) on certain enzymological and histopathological biomarker responses of a freshwater fish Cyprinus carpio

Abstract In this study the toxicity of antimalarial drug chloroquine (CQ) on certain enzymological (GOT, GPT and LDH) and histopathological alterations (Gill, liver and kidney) of a freshwater fish Cyprinus carpio was studied after acute (96h) and sublethal (35days) exposure. The median lethal concentration (96h) of CQ was 31.62mg/ml. During acute treatment (CQ at 31.62mg/ml) the treated fish groups showed a significant increase in GOT and GPT activities in blood plasma; whereas LDH activity was decreased when compare to control groups. To analyse the effects of drug at the lowest concentration, the fish were exposed to 3.16mg/ml (1/10th of 96h LC50 value) for 96h. In sublethal treatment (3.16mg/ml) GOT activity increased up to 14th day and decreased during the rest of the exposure period (21, 28 and 35th day). A biphasic response in GPT activity was observed. LDH activity was found to be increased throughout the study period (35days) compare to control groups. The alterations in enzyme activities in blood plasma were found to be significant at p<0.05 (DMRT). Many histopathological changes in vital organs such as gill, liver and kidney of fish were observed in CQ treated group (acute and sub-lethal) compare to normal group. The alterations in the enzymological and histopathological study in the present investigation indicate that the drug CQ has toxic effects on non-target organisms. We conclude that the alterations in enzymological parameters and histopathological changes can be used as biomarker to assess the health of the aquatic organism/environment. Further data on molecular studies are needed to define the mode of action and toxicity of these emerging pollutants.

Responses of Labeo rohita fingerlings to N-acetyl-p-aminophenol toxicity

The short term (96 h) toxicity of N-acetyl-p-aminophenol (0.58 mg/L - Treatment I and 0.29 mg/L - Treatment II) on certain health indicators (haematology, biochemical, and enzymology) of an Indian major carp Labeo rohita was studied. When compared to control, N-acetyl-p-aminophenol treated fish showed a significant (P < 0.05) decrease in haemoglobin (Hb), haematocrit (Hct), and erythrocyte (RBC) levels throughout the study period. Whereas, a significant (P < 0.05) increase were noted in leucocyte (WBC) counts (except 48 h in Treatment-I), mean corpuscular volume (MCV), and mean corpuscular haemoglobin (MCH) values (except 24 h in Treatment-I). Mean corpuscular haemoglobin concentration (MCHC) values were found to be decreased significantly (P < 0.05) in fish exposed to 0.58 mg/L of N-acetyl-p-aminophenol, whereas in 0.29 mg/L exposed fish the values were found to be increased significantly (P < 0.05) (except 72 h). A significant (P < 0.05) increase in plasma glucose levels was noticed in fish exposed to 0.58 mg/L of N-acetyl-p-aminophenol (except 96 h). However, a biphasic trend in plasma glucose level was observed at 0.29 mg/L of N-acetyl-p-aminophenol exposed fish. Protein levels were found to be increased in both the treatments except at the end of 48 and 96 h in 0.58 and 0.29 mg/L, respectively. In both the treatments fluctuations of enzyme (GOT, GPT, and LDH) activities in gill and liver were also noted. However, these enzyme activities found to be significantly (P < 0.05) decreased in kidney and plasma of fish. From the result we conclude that the drug N-acetyl-p-aminophenol upon short term exposure could pose a risk to fish and the alteration of these parameters can be used to ecological risk assessment of pharmaceuticals in aquatic organisms.