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This study investigated the influence of the pesticide methomyl on different enzymatic activities in carp. The fish were exposed to a sub-lethal concentration (0.34 mg L^sup -1^) of methomyl for 15 days. On days 4 and 15, catalase (CAT) and glutathione-S-transferase (GST) activities were measured in the liver and gills. Acetylcholinesterase (AChE) activity in brain and muscle was also determined. Liver catalase activity slightly increased in exposed fish when compared to controls, but it was statistically significant only at the beginning of the experiment. No changes in CAT activity in the gills of exposed and control animals were observed (mean values were in the range 10.7-11.7 nmol min^sup -1^ per mg of protein). Liver GST activity was slightly inhibited in the exposed animals at the beginning of the study; however, it was significantly inhibited in the gills. Brain AChE activity was diminished throughout the experiment and significantly decreased after 96 h of exposure compared to controls (0.041 vs. 0.075 nmol min^sup -1^ per mg of protein; p<0.001). Our findings suggest that CAT, GST, and AChE are reliable biomarkers of effect after exposure to methomyl.
KEY WORDS: acetylcholinesterase; carbamate; catalase; fish; glutathione S-transferase
Sazetak
Razlike u enzimskim aktivnostima u tkivima sarana (Cyprinus carpio L.) kao moguci bioloski pokazatelji izlozenosti pesticidu metomilu
Istrazen je utjecaj pesticida metomila na razine enzimskih aktivnosti u tkivima sarana izlozenih subletalnoj koncentraciji od 0,34 mg L-1 tijekom 15 dana. Nakon 4 i 15 dana u jetrima i skrgama pokusnih zivotinja izmjerene su aktivnosti katalaze i glutation S-transferaze (GST), a aktivnost acetilkolinesteraze (AChE) u mozgu i misicima. Aktivnost katalaze u jetrima blago se smanjila u izlozenih riba u usporedbi s kontrolnom skupinom, no to je smanjenje bilo statisticki znacajno tek na pocetku pokusa. Istovremeno nisu zamijecene znacajne promjene u aktivnosti katalaze u skrgama izlozenih i kontrolnih riba (srednje vrijednosti bile su u rasponu 10,7-11,7 nmol min-1 po miligramu proteina. Dok je aktivnost enzima GST u jetrima izlozenih riba bila tek blago inhibirana na pocetku pokusa, u skrgama je utvrðena znacajna inhibicija. Aktivnost acetilkolinesteraze u mozgu s vremenom se smanjivala i pokazala znacajan pad nakon 96 sati izlozenosti (0,041 vs. 0,075 nmol min-1 po miligramu proteina; p<0.001). Rezultati upucuju na zakljucak da su katalaza, GST i AChE pouzdani bioloski pokazatelji ucinka izlozenosti metomilu.