INDUCTION OF MICROSOMAL OXIDASES BY DIELDRIN IN MUSCA DOMESTICA

Abstract

Dieldrin is a potent inducer of microsomal naphthalene hydroxylase and heptachlor epoxidase in the housefly, causing up to five‐fold increases in the activities of these enzymes. The activation of these detoxifying enzymes is also demonstrated in vivo by a reduction in the susceptibility of the dieldrin‐treated insects to carbaryl. The inductive effect is prevented in insects treated with the drug cycloheximide, an inhibitor of protein synthesis. Dieldrintreated flies also incorporate more amino acid into protein. Under similar experimental conditions, DDT is a less effective inducer. Three housefly strains, all resistant to dieldrin but with differing levels of microsomal oxidase activity, were compared in terms of dieldrin dose, rate of appearance of the inductive effect, response on aging, and response to a second treatment with dieldrin. All of the strains, both male and female, were induced, as indicated by increased epoxidation of heptachlor. However, the strain with the lowest pretreatment microsomal oxidase activity, dieldrin‐curly wing, responded least while the strain with the highest basal microsomal oxidase activity, Isolan, responded most to the dieldrin treatment. Comparing the three strains on the basis of maximum increases in heptachlor epoxide production, induction in the Isolan and Orlando strains was approximately three and two times, respectively, that found in the dieldrin‐curly wing strain. It is suggested that this difference in response to the inducing agent represents differences in the number of structural genes for oxidase synthesis in the three strains. The results are discussed in terms of genetic control. Résumé INDUCTION DES OXYDASES MICROSOMIALES PAR LA DIELDRINE CHEZ MUSCA DOMESTICA Chez la mouche domestique, la dieldrine est un inducteur efficace de la naphtalène‐hydroxylase et de l'heptachlore‐epoxydase, augmentant jusqu'à cinq fois l'activité de ces enzymes. L'activation de ces enzymes de détoxification est démontrée aussi in vivo, par une baisse de la sensibilité au carbaryl des insectes traités à la Dieldrine. L'effet inducteur est supprimé par un inhibiteur de la synthèse des protéines, la cyclo‐heximide. De même l'incorporation des acides aminés dans les protéines est diminuée chez les mouches traitées à la Dieldrine. Dans des conditions expérimentales équivalentes, le D.D.T. est un inducteur moins efficace. Trois souches de mouches domestiques, toutes les trois résistantes à la Dieldrine, mais dont les oxydases possèdent des niveaux d'activité différents, ont été comparées pour les facteurs suivants: dose de Dieldrine, taux d'apparition de l'effet inducteur, âge, et effet d'un second traitement à la Dieldrine. L'induction se vérifia, dans toutes les souches, à la fois chez les mâles et les femelles, par une augmentation du taux d'époxydation de l'heptachlore. Cependant, la souche possédant à l'origine la plus faible activité oxydasique, la souche «dieldrin‐curly wing», a une réponse inférieure à la souche «Isolan» dont les oxydases possèdent la plus forte activité originel...

Permeation of Dry Seeds with Chemicals: Use of Dichloromethane

“…Different species respond differently to the toxin (1), but susceptibility of man is unknown. Human exposure sometimes occurs (4,5), and evidence presented in case reports implicates aflatoxin in acute poisoning (6) and supports the hypothesis that aflatoxin exposure is associated with elevated incidence of primary liver cancer in certain populations (7).…”

Consequences of Induction of Foreign Compound-Metabolizing Enzymes in Insects

“…The PSMOs can be induced by a variety of chemicals with diverse structures including insecticides such as DDT and cyclodienes (Walker and Terriere, 1970;Plapp and Casida, 1970;Yu and Terriere, 1972;Khan and Matsumura, 1972); insect hormones and growth regulators such as ecdysone and juveni le hormone Terriere, 1971, 1975;Terriere and Yu, 1976), organic solvents such as pentamethylbenzene (Brattsten and Wilkinson, 1973;, drugs such as phenobarbital and 3-methylcholanthrene (Agosin et al, 1969;Yu and Terriere, 1973;Gil et al, 1974;Brattsten et al, 1976;Yu and lng, 1984), butylated hydroxy toluene and triphenyl phosphate (Perry et al, 1971), and allelochemicals such as terpenoids, indoles and flavonoids (Brattsten et al, , 1984Yu, 1982a;Yu, 1983).…”

Metabolic Interactions Among Environmental Chemicals and Drugs

“…Exposure of the housefly, Musca domestica L., to DDT or dieldrin enhanced the metabolism of DDT, aldrin, allethrin, propoxur, and diazinon (99). The microsomal oxidation of heptachlor and naphthalene was increased severalfold in dieldrinresistant houseflies exposed to sublethal doses of dieldrin (100), and the susceptibility of these insects to carbaryl was decreased. The ability of halogenated hydrocarbon pesticides to stimulate their own metabolism and the metabolism of other pesticides by microsomal enzymes suggests that the resistance and cross-resistance that occurs in insects after they have been sprayed with various chemicals may, in part, result from the induction of enzymes that detoxify pesticides in insect microsomes.…”