International Research Journal of Environment Sciences________________________________ ISSN 2319–1414Vol. 4(9), 21-24, September (2015) Int. Res. J. Environment Sci. International Science Congress Association 21 Effects of an Organophosphate Pesticide, Malathion (50% E.C) on the Liver of air breathing fish, Heteropneustes fossilisBarbhuiya Hasina Begum* and Dey MithraDepartment of Ecology and Environmental Science, Assam University, Silchar-788011, Assam, INDIAAvailable online at: www.isca.in, www.isca.me Received 26th May 2015, revised 30th June 2015, accepted 6th July 2015 AbstractIn the present study histological alterations in the liver of Heteropneustes fossilis was studied after exposure to malathion. Fishes were exposed to 1.07ppm (1/10th of 96h LC50) concentration of malathion. The experiment was maintained for 21 days. Light microscopic study of liver of the treated fishes showed haemorrhage, formation of vacuoles and appearance of macrophages. Degeneration of hepatocytes and fibrous tissue invaded with some inflammatory cellswere also observed in malathion treated liver of Heteropneustes fossilis.Keywords: Malathion, Heteropneustes fossilis, liver, histological alteration. Introduction Pesticides are extensively used throughout the world for pest control. Among the different types of pesticides organophosphates have become one of the widely used classes of insecticides. These types of insecticides have low solubility and also degrade very rapidly. Because of this reason exposure of aquatic organisms to organophosphates is difficult to assess. But such insecticides are highly toxic to aquatic organisms and therefore monitoring the impact of these insecticides is essential. In aquatic toxicology, fish plays an important role in toxicity testing and hazard evaluation, as do the white rat and guinea pig in mammalian toxicology. Pesticidal pollution not only has adverse effects on fish production but it also constitutes the most dangerous health hazard. Fishes are quite sensitive to a wide variety of toxicants and are used as indicator of pollution in water-quality management. Toxicants impair both the metabolic and physiological activities of the organisms. But only physiological studies are not sufficient for the complete understanding of pathological conditions of tissues under the stress of toxicants. Hence it is essential to have an insight into histological analysis. The severity of tissue damage is a consequence of the concentration of toxicant and it is time dependent. Tissue damage is also related to the toxic potentiality of a particular compound or pesticide accumulated in the tissues. Histopathological changes are widely used as biomarkers in the evaluation of the effect of contaminants on fish health both in the laboratory5,6 and field studies7, 8. Such type of biomarker not only allows examining specific target organs which are responsible for vital functionsbut also provides information regarding to the damage of animal health10. Material and Methods Live specimens of Heteropneustes fossilis (10-12 cm in length and 4-6 gm in weight) were collected locally. Fishes were washed with 0.5% KMnO4 solution for five minutes to remove any external infections and then acclimatized under laboratory condition for a period of 15 days prior to experiment. The physico-chemical characteristics of water which was used for the experiment were pH 6.4±.04, dissolved oxygen 7.8±0.32mg/l and temperature 28±0.47C. Commercial fish food was given to fishes during acclimatization. Water of the aquarium was changed daily. The dead fishes were removed immediately. For histological study 1.07 ppm concentration of malathion was taken which was the 1/10th concentration of 96h LC50 value of malathion. The experiment was continued for 21 days. Ten fishes with replicate were maintained in test solution along with control. During the experiment fishes were fed once a day and uneaten food was removed 30mins after feeding. After 21 days both the control and pesticide treated fishes were sacrificed for histological study. Liver was dissected and kept in formaldehyde for 24 h, then dehydrated, embedded in paraffin and sections were cut at 5 m thickness and stained with haematoxylin and eosin. Slides were viewed under Olympus CX41 microscope (X100) and photographs were taken. Results and Discussion The organ which is associated with the detoxification process and biomarker process is the liver. Because of function, position and blood supply this organ is also one of the most affected organ by contaminants in water11. The liver is susceptible to a number of toxicants and serves as an index to toxicity of surrounding water12. Liver is the main storage and central metabolizing organ that plays a dual role of secretion of International Research Journal of Environment Sciences _____________________________________________ ISSN 2319–1414Vol. 4(9), 21-24, September (2015) Int. Res. J. Environment Sci. International Science Congress Association 22 digestive enzymes and as storage organ for nutrients13. Histological observation of liver from control fish in the present study showed normal homogenous mass of hepatocytes with no abnormalities. Sinusoids and central vein were systematically arranged. (figure-1 and figure-2). After treatment with malathion the liver of Heteropneustes fossilis showed several pathological alterations. In the present study malathion induced haemorrhage (figure-3) in the liver of Heteropneustes fossilis. Break down of blood vessels may result in haemorrhagic area. This type of finding was reported by many authors after toxicant exposure. Haloi et al.14 found haemorrhage in the endosulfan treated liver of Channa puctatus. Ganesan et al.15 studied the histopathological impact of sublethal concentrations of 1, 2 dichlorobenzene on the liver of Catla catla and reported similar observation. Formation of vacuoles (figure-4) was one of the common alteration in the malathion treated liver. This is probably due to metabolic damage related to exposure with pesticide contaminated water16. This finding is in agreement with Ba-Omar et al17. The histopathological appearance of liver of Tilapia zilliiexposed to aluminum also showed cytoplasmic vacuolization which was studied by Hadi and Alwan18. Vacuoles in cytoplasm of liver tissue of Oncorhynchus mykiss was also observed by Velisek et al19 after exposure to bifenthrin. Appearance of macrophages (figure-5) were also observed in the present study. Doaa and Hanan20 reported macrophages aggregation in lead treated liver of Oreochromis niloticus. The macrophages usually take up scavenger molecules. Scavenger materials are degraded within the vacuoles of macrophage and reused in the synthesis of new substances21,22. In the present study malathion induced degeneration of hepatocytes (figure-6) in the liver of Heteropneustes fossilis. This finding is in agreement with Muthukumaravel et al23who studied histopathological impact of monocrotophos on the liver of Labeo rohita. Degenerating hepatocytes were also reported by Ahmed et al24 in cadmium chloride treated liver of Clarias batrachus. Fibrous tissue invaded with some inflammatory cells (figure-7) was also observed in the present study. According to Kadryet al25 atrazine also resulted in similar pathological alteration in the liver of Clarias gariepinus. Conclusion From the present study it can be concluded that sub lethal concentration of malathion resulted in a large number of histopathological alterations in the liver of fish which is a non target and economically important organism. Liver perform many important functions like detoxification, metabolism and secretion of digestive enzymes. It also acts as a storage organ of essential nutrients. So, histopathological alterations like haemorrhage, formation of vacuoles appearance of macrophages, degeneration of hepatocytes etc. as observed in the present study can result in metabolic disturbances. Such disturbance can have an adverse effect on fish health. Figure-1 Control liver showing central vein (100X) Figure-2 Control liver showing hepatocytes (white arrow) and sinusoids (black arrow) (100X) Figure-3 Malathion treated liver showing haemorrhage (100X) International Research Journal of Environment Sciences _____________________________________________ ISSN 2319–1414Vol. 4(9), 21-24, September (2015) Int. Res. J. Environment Sci. International Science Congress Association 23 Figure-4 Malathion treated liver showing formation of vacuoles (100X) Figure-5 Malathion treated liver showing appearance of macrophages (100X) Figure-6 Malathion treated liver showing degeneration of hepatocytes (100X) Figure-7 Malathion treated liver showing fibrous tissue invaded with some inflammatory cells (100X) AcknowledgementAuthors are grateful to University Grant Commission (UGC), New Delhi, India for the fellowship. 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