Methods in Anopheles Research - MR4

Chapter 5 : Insecticide Resistance Monitoring5.2 Microplate Enzyme Activity AssaysPage 3 of 4• Bottles of various sizes to store chemical solutions• Graduated cylinders• pH meter• Laboratory stirrerabsorbance oxidase21.81.61.41.210.80.60.40.20susceptiblepermethrin-selected0 0.5 1 1.5absorbance esteraseFigure 5.2.3. Oxidase and esterase absorbances of individual mosquitoes have beenplotted for two populations in an XY graph. In this example, permethrin exposure has beenapplied and has increased the level of resistance observed in bioassays. The upper limit ofoxidase activity in the unselected population is indicated by the horizontal line. Manyindividuals in the permethrin-selected stock now have elevated levels of oxidase thoughthe level of esterase has not been affected.Reagent Preparation:0.25 M Potassium Phosphate Buffer [KPO 4 ]1. Place 800 ml purified water in a glass beaker on a stirrer2. Add 6.6 g dibasic potassium phosphate3. Add 1.7 g monobasic potassium phosphate4. Adjust to pH 7.2 using one of the above.5. Store at room temperature6. Adjust to 1000 ml final volume