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  • br Materials and methods br Results br


    Materials and methods
    Discussions The treated tannery effluent (both MF and MF+RO treated) was free from most of the organic and inorganic loadings as reflected from the values of COD, BOD, total kjeldahl nitrogen (TKN) and sulfides etc. Toxicity study of the effluent (both treated and untreated) was conducted on P. globosa, a fresh water snail. The results thus obtained are discussed in the following section. The enzyme activities (SOD, CAT, GST, GR and GP) were found to decrease in MF treated effluent compared to that of the untreated effluent. In case of MF+RO treatment, the activity was observed close to that of the control. Activity of SOD and CAT in untreated effluent increased in comparison to control due to increased level of reactive oxygen species (ROS) induced antioxidative levels. This level increases when the Silydianin receptor is under stress and to manage with the stress, the enzyme activities increase. GP plays an important role in protecting an organism from oxidative damage caused by heavy metals like chromium and other toxic organic and inorganic pollutants present in untreated tannery effluent. Similar effect was observed in gold fish that exhibited oxidative stress in response to chromium toxicity. Significant alterations in enzyme activity like SOD, CAT etc. were observed in addition to DNA damage (Velma and Tchounwou, 2010). Glutathione reacts with superoxide radicals, peroxy radicals, etc. thereby exerting its antioxidative function. The main function of GP is to catalyze reduction of H2O2, thereby protecting organism from oxidative damage. Tsangaris et al. (2010) assessed the pollution impacts in mussel wherein the responses of the antioxidant enzyme glutathione peroxidase indicated the possible presence of pesticide contaminants capable of ROS production. Activity of GR is to protect cellular membranes from H2O2 by maintaining optimum level of GSH. On the other hand GST detoxifies various carcinogenic compounds causing DNA damage (Velma and Tchounwou, 2010, Tsangaris et al., 2007). The whole body is directly exposed to the effluent which results in increased activity of enzymes. Enzyme activities increased in mantle tissue due to entry of toxic components by endocytosis or transportation of metals into cells. Gonad also has the ability to incorporate heavy metals thus increasing the enzyme activity (Gagné et al., 2007). It may be noted that the MF treatment facilitated significant reduction of the pollutant loadings resulting into lower activity of the stress enzymes as compared to the untreated effluent. The MF+RO treatment further enhanced the quality of the effluent including removal of the dissolved contaminants which has been reflected in the values of stress enzyme activities almost to control. Carbohydrate, protein and amino acid content in P. globosa following exposure to MF and MF+RO treated effluent were less hampered. Carbohydrates are an important biomolecule which is stored in organism and releases energy under stressed conditions. When an organism is under stress due to various factors like toxic heavy metals, organic substances, etc. the body derives energy by breaking the glucose molecules. Therefore reduction in carbohydrate level in the untreated effluent might be related to its rapid utilization to combat the stress which has been overcome considerably on application of the treated effluents and subsequently, carbohydrate content was observed to increase. Compared to the treated effluents, the reduction in total protein content of molluscs exposed to the untreated effluent might be due to faster breakdown and subsequent utilization of the byproducts by the tissues. On the other hand, increase in total free amino acid content of molluscs in 100% effluent might be due to more protein degradation and less utilization of amino acid in protein synthesis due to imbalance in the metabolic activities which could be prevented considerably for the treated effluents. The results also imply that the acid–base balance of the body is inhibited in exposure of the effluent due to insufficient use of amino acids. Similar phenomenon has been observed on Lymnaea acuminate (Chauhan et al., 2011).