Master Dissertation
This study was conductedto investigate the effect of Actellic Super (pirimiphos-methyl) in Oreochromis niloticus (Nile tilapia)in Mvomero District, Morogoro, Tanzania. Field surveys using questionnaire interviews were used to collect sociological data from households that own fish ponds. The response of Acetylcholinesterase(AChE) and Pseudocholinesterase (BuChE/PChE) activities in O. niloticusas a result of Organophosphates (OPs) and carbaryl water borne exposure was determined in plasma and brain samples of fish usingEllman’s method and 5,5’-dithiobis-2-nitrobenzoic acid (DTNB) chromophore. . The in vivodose-effect relationships were assessed using pirimiphos-methyl at 0.04,0.08 and 0.16µM. The majority, 56% (n=25) of respondents with the age above 51 years practiced fish farming. Males 64.0% (n=25) were more than females. Sixty eight percent of all respondents (n=25)had primary education.Oreochromis niloticus was the most keptfishspeciesbecauseof its good and lucrative market.Moreover, 24percent (n=25) of respondents used pirimiphos-methyl. Concentrations that inhibited 50% (IC50) of AChE activities in brain in in vitroexposures were 0.004, 0.005 and 1.307mMand in BuChE exposure were0.743,0.007and 0.031 mM for carbaryl, pirimiphos-methyl, and profenofos respectively. Also,concentrations that inhibited 50% (IC50) of AChE and BuChE activities in plasma in in vitroexposurewere 1.801,0.031and 0.630mM for carbaryl, profenofos and pirimiphos-methyl and 0.045, 0.153and 0.091 mM for carbaryl, pirimiphos-methyl and profenofos respectively. Following in-vivoexposure of fish to pirimiphos-methyl at concentrations of 0.16µMa significant inhibition of AChE (53%), PChE (90%) activities in plasma and AChE (50%), PChE (75%) in brain was observed respectively. The investigation from this work revealed that inhibition of AChE and BuChE activity in O. niloticusis a useful biomarker for assessing aquatic environmental pollutants by anticholinesterases.