SUBCELLULAR-DISTRIBUTION AND CHARACTERIZATION OF ESTERASE ISOZYMES FROM INSECTICIDE-RESISTANT AND INSECTICIDE-SUSCEPTIBLE STRAINS OF GERMAN-COCKROACH (DICTYOPTERA, BLATTELLIDAE)

Esterases from insecticide-resistant and -susceptible strains of Germa n cockroach, Blattella germanica (L.), were isolated and analyzed for differences in activity. The isozymes E5, E6, E7, and E8 of resistant strains indicated about two- to fivefold increases in activity compare d with those of the susceptible strain. These isozymes constituted alm ost-equal-to 60% of the total activity in the resistant strains, where as they contributed only about 40% activity in the susceptible strain. Subcellular distribution studies showed that most esterase activity i s present in the 100,000 x g fraction of the homogenate (cytosolic). O nly a small portion of activity was membrane bound. Molecular weights of the esterase isozymes calculated based on their retardation coeffic ients ranged between 48 and 81 kd.