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(W/MF139) Effects of xenobiotics on cage-cultured Nile tilapia (Oreochromis niloticus) in Laguna de Bay, Philippines. Körner, Oliver1, Pagulayan, Roberto2, Preuß, Thomas1, Schill, Ralph1, Köhler, Heinz-R.1, Triebskorn, Rita1,3, 1 2 3 ABSTRACT- In the present study, we examined the influence of xenobiotics on the tropical teleost Nile tilapia (Oreochromis niloticus) in different fish cage areas of Laguna de Bay, Philippines in comparison to a non-polluted site at Lake Taal, Philippines. Laguna de Bay, the largest lake of the Philippines, is influenced by various kinds of organic and inorganic contaminants. To assess risk for fish in this important fishery ground, we used different histological and biochemical biomarker responses, namely the occurrence of pathological symptoms in gills and gonads, and the expression of the heat shock proteins hsp70 and hsp90 in the liver. Determination of heat shock proteins, particularly of hsp70, has been shown to be suitable as a tool to investigate several kinds of environmental stress (e.g. pollution and temperature stress) in aquatic organisms. In the present study, we focused not only on general stress but also on possible impact of endocrine disruptors on fish development using hsp90 and gonad histology as biomarkers. Hsp90 has been shown to be associated with estrogen receptors (ER) prior to any steroid-receptor interaction, and to modulate the hormonal response. After formation of the steroid-receptor-complex, hsp90 is released from the receptor. Compared to hsp70, levels of hsp90 in non-stressed cells are relatively high. However, differences between receptor-bound and released fractions of hsp90 can be used as a marker for the action of xenohormones on this system. To separate these two fractions, we used Native PAGE followed by Western blotting. Key words: biomarker, heat-shock-proteins, histopathology, fish |
