Influence of enzyme levels on the toxicity and in vitro metabolism of 2,2',5-trichlorobiphenyl in houseflies.
Adult female houseflies (Musca domestica) were topically dosed with 10, 15, and 20 micrograms of 2,2',5-trichlorobiphenyl (PCB-18) in acetone at 1, 5, and 15 days following emergence. These doses caused a significant decrease in the mean survival time in 5-day-old flies. LT50's (time for 50% death) were dramatically reduced in 5-day-old flies, whereas no significant difference was found at any treatment level in 15-day-old flies. Abdomenal microsomal enzyme levels were determined by the rate of O-dealkylation of (p-nitrophenyl)ethyl ether for 1-, 5-, 11-, and 15-day-old female houseflies. The highest levels were found in 5-day-old flies and the lowest in 15-day-old flies. The greatest metabolism of PCB-18 by housefly microsomes also occurred in 5-day-old flies. The enzyme levels, metabolism, and toxicity suggest that PCB-18 is bioactivated to a product(s) which reduces the mean survival time of houseflies.
Saghir
S A
SA
College of Veterinary Medicine, University of Illinois, Urbana 61801.
Hansen
L G
LG
D000375:Aging / Q000502:physiology; D000818:Animals; D001345:Autoradiography; D001711:Biotransformation; D001835:Body Weight / Q000187:drug effects; D003640:Dealkylation; D004785:Environmental Pollutants / Q000378:metabolism* / Q000493:pharmacokinetics / Q000633:toxicity*; D005260:Female; D006793:Houseflies / Q000201:enzymology*; D007305:Insecticide Resistance; D008136:Longevity; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology; D011078:Polychlorinated Biphenyls / Q000378:metabolism* / Q000493:pharmacokinetics / Q000633:toxicity*
D004785:Environmental Pollutants; C078449:2,2',5-trichlorobiphenyl; D011078:Polychlorinated Biphenyls