Changes in fatty acid content of the liver and gill tissue of Oreochromis niloticus exposed to various pesticides

In this study, it was aimed to investigate changes that can occur in total, phospholipid (PL) and triacylglycerol (TAG) fatty acid fraction in the liver and gill tissues of Oreochromis niloticus exposed to the sublethal concentrations of Diazinon from the group of organophosphate, Carbaryl from the group of the carbamate, Atrazine from the triazine group and Lambda cyhalothrin from the pyrethroid group for 7, 14 and 21 days. Pesticides are widely used chemical compounds or biological agents in many areas, especially in the fight against harmful effects that adversely affect agricultural production. Although the use of these substances has several benefits, they can also lead to ecological problems due to potential toxicity to humans and other living things by reaching the natural environment in various ways. The chemical stability and widespread use of these compounds have caused serious contamination in natural waters. Therefore, it is important to know that these pollutants transmitted to the natural environment can bring about what kind of toxicological effects on the organisms living in these environments. Different methods are used to investigate the effects of pesticides on organisms. Among these methods, the toxicological tests applied to the conditions which are similar to the environmental conditions and giving the best results are leading one. Assessing the ecotoxicological risks of pesticides in ecosystems is based on data for the toxicity and effects of non-target organisms of pesticides. The obtained data are analyzed and the adverse effects of the pesticides on the organisms are determined. Thus, necessary measures can be taken against these adverse effects. Fish are a good indicator of water contamination, because the biochemical stress response is very similar to that in mammals. Toxicological investigations are used in a biologically effective way to diagnose metabolic impairments caused by potential pollution conditions of the water environment that occur due to very low concentrations of pollutants that appear days or weeks later. Toxicological responses are highly susceptible to determine environmental contamination, since aquatic organisms are in balance with the environment in which they are present. There is a significant relationship between the biochemical effects that occur in the organism and those that occur in the population. In our study, fish were exposed to subletal concentrations of Diazinon, Carbaryl, Atrazine and Lambda cyhalothrin for 21 days and changes in the total, phospholipid (PL) and triacylglycerol (TAG) fatty acid fractions in the liver and gill tissues of Oreochromis niloticus were investigated by Gas Chromatography (GC). When compared with control fish, the applied pesticides caused different percentages of total saturated, n-9, n-6, n-3 fatty acids and on different days. According to the results of gas chromatography, out of saturated fatty acid, myristic acid (14:0), pentadecanoic acid (15:0), palmitic acid (16:0), heptadecanoic acid (17:0) and stearic acid (18:0); out of monounsaturated fatty acids, palmitoleic acid (16:1(n-7)), oleic acid (18:1(n-9)) and eicosenoic acid (20:1(n-9)); out of polyunsaturated fatty acids, linoleic acid (18:2(n-6)), linolenic acid (18:3(n-3)), eicosadienoic acid (20:2(n-6)), eicosatrienoic acid (20:3(n-6)), arakidonic acid (20:4(n-6), AA), eicosapentaenoic acid (20:5(n-3), EPA), docosapentaenoic acid (22:5(n-3)) and docosahexaenoic acids (22:6(n-3), DHA) were determined in the liver and gill tissues of O. niloticus. In the present study, percents of SFA (Saturated Fatty Acids), MUFA (Monounsaturated Fatty Acids) and PUFA (Polyunsaturated Fatty Acids) varied depending on different tissues and different pesticide exposures of the same fish species. When the total fatty acids in the liver tissue of the control fish are considered, the most important fatty acids were found to be C16:0 and C18:0 from SFA; C18:1 from MUFA; C18:2(n-6) and C22:6(n-3) from PUFA. The most variable fatty acids in pesticide-applied fish were C16:0, C18:1, C18:2(n-6) and C22:6(n-3) on which Carbaryl was applied; C18:1 and C22:6(n-3) on which Diazinon was applied; C18:1, C18:2(n-6) and C22:6(n-3) on which Lamda cyhalothrin was applied, and C16:0 and C18:2(n-6) on which Atrazin was applied. When the total fatty acids in the gill tissue of the control fish are considered, the most important fatty acids were found as C16:0 and C18:0 from SFA; C18:1 from MUFA; C18:2(n-6), C18:3(n-3) and C22:6(n-3) from PUFA. There were significant changes in fatty acids in fish such as C18:0, C18:2(n-6) ve C22:6(n-3) in fish exposed to Carbaryl; C16:0, C18:0, C18:1 and C18:3(n-3) in fish exposed to Diazinon; C16:0, C18:0 and C18:3(n-3) in fish exposed to Lamda cyhalothrin; C16:0, C18:0, C18:1, C18:2(n-6) ve C18:3(n-3) in fish exposed to Atrazin. When the fatty acids in the phospholipids (PL) in the liver tissue of the control fish are considered, the most significant fatty acids were found to be C16:0 and C18:0 from SFA; C18:1 from MUFA; C18:2(n-6), C20:4(n-6) and C22:6(n-3) from PUFA. The most variable fatty acids in pesticide-applied fish were C16:0, C18:0 and C22:6(n-3) in the group on which Carbaryl was applied, C18:1 and C22:6(n-3) in the group on which Diazinon was applied, C18:1 and C22:6(n-3) in the group on which Lamda cyhalothrin was applied, and C16:0, C18:2(n-6) and C22:6(n-3) in the group on which Atrazin was applied. When fatty acids found in the phospholipids (PL) in the gill tissue of the control fish are considered, it was found that the most significant fatty acids were C16:0 and C18:0 from SFA; C18:1 from MUFA; C18:2(n-6), C20:4(n-6) and C22:6(n-3) from PUFA. There were significant changes in C16:0, C18:0, C18:2(n-6), C20:4(n-6) and C22:6(n-3) fatty acids in fish exposed to Carbaryl; C22:6(n-3) in fish exposed to Diazinon; C18:0 and C22:6(n-3) in fish exposed to Lamda cyhalothrin; C18:2(n-6) and C22:6(n-3) in fish exposed to Atrazin. When the fatty acids found in the triacylglycerols (TAG) in the liver tissue of the control fish were considered, the most significant fatty acids were C16:0 and C18:0 from SFA; C16:1 and C18:1 from MUFA; C18:2(n-6) and C20:4(n-6) from PUFA. The most variable fatty acids in pesticide-applied fish were C16:0, C18:1 and C22:6(n-3) in the one on which Carbaryl was applied; C16:0, C18:1 and C22:6(n-3) in the fish on which Diazinon was applied; C16:0, C18:0, C18:1 and C22:6(n-3) in the fish on which Lamda cyhalothrin was applied; C16:0, C18:0, C18:1 ve C18:2(n-6) in the fish on which Atrazin was applied. When the fatty acids found in the triacylglycerols (TAG) in the gill tissue of the control fish were considered, the most significant fatty acids were found to be C16:0 and C18:0 from SFA; C16:1, C18:1 and C20:1 from MUFA; C18:2(n-6) and C22:6(n-3) from PUFA. There were significant changes in fatty acids in fish such as C16:0, C18:0, C18:1 and C18:2(n-6) fatty acids in fish exposed to Carbaryl; C16:0, C18:0, C18:1 and C18:2(n-6) in fish exposed to Diazinon; C16:0, C18:0, C18:1 and C18:2(n-6) in fish exposed to Lamda cyhalothrin; C18:1 and C18:2(n-6) in fish exposed to Atrazin. As a result of the study, it was determined that there were irregular decrease and increase in fatty acid percentage of total, phospholipid (PL) and triacylglycerol (TAG) in the liver and gill tissues of O. niloticus exposed to the sublethal effect of pesticides compared to those of the controls. Our studies have shown that almost similar effects are observed on total, phospholipid (PL) and triacylglycerol (TAG) fatty acid fraction due to exposure and duration to organochlorine, organophosphorus, pyrethroid and carbamate pesticides, and that these pesticides affect the desaturation and elongation pathways of the fatty acids which, in turn, cause changes. It is an important point that fatty acids, which are the main component of living cell and organelle membranes, are affected by the membrane enzyme reaction. Keywords: Oreochromis niloticus, Liver, Gill, Total Lipid, Phospholipid, Triacylglycerol, Toxicology, Pesticide, Atrazin, Diazinon, Lambda-cyhalothrin, Carbaryl.