In vitro inactivation of corpora allata of the bugOncopeltus fasciatus by precocene II

Müller, Peter; Masner, P.; Kälin, Maria; Bowers, William S.

doi:10.1007/bf01960409

Cited by 25 publications

(3 citation statements)

References 6 publications

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“…Bioactivation, if required, must occur in the target tissue, since the epoxide formed elsewhere is probably not stable enough to undergo transport within the insect. Since 1 inactivates CA in tissue culture (Pratt and Bowers, 1977;Müller et al, 1979) and epoxidation (detected as diol formation) is observed with milkweed bug corpora allata incubated with 3H-labeled 1 in vitro (Aldrich and Soderlund, 1979), it appears that if 1 in fact is bioactivated, such reactions occur in the CA itself. The ability of the 6,7- methylenedioxyphenyl-substituted analogue of 1 to prevent the antihormonal action of 1 in vivo (Brooks et al, 1979) provides further evidence for an oxidative activation step.…”

Section: Metabolismmentioning

confidence: 99%

Precocene II Metabolism in Insects: Synthesis of Potential Metabolites and Identification of Initial in Vitro Biotransformation Products

Soderlund¹,

Messeguer²,

Bowers³

1980

J. Agric. Food Chem.

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Syntheses are described for the following derivatives of the insect antijuvenile hormone precocene II (6,pyran), all of which are possible metabolites in insects: 6hydroxy, 7-hydroxy, 3,4-dihydro-3-hydroxy, cisand irans-3,4-dihydro-3,4-dihydroxy, 2-hydroxymethyl, 3,4-dihydro-4-hydroxy, and 3,4-epoxy. Of these, the first five are identified by cochromatography as metabolites of [14C]precocene II formed in vitro on incubation with NADPH-dependent monooxygenases in fat body homogenates of cabbage looper (Trichoplusia ni Hübner) larvae. The 3,4-epoxide is inferred as a metabolic intermediate from the presence of the isomeric dihydrodiols, but could not be isolated directly. The extreme reactivity of the synthesized epoxide suggests this compound as a possible bioactivation product involved in the allatotoxic action of precocene II. One metabolite, which is apparently nonphenolic, has properties different from the synthesized standards and remains to be identified.Precocene II (6,7-dimethoxy-2,2-dimethyl-2H-benzo-[6]pyran, 1) is selectively cytotoxic to the secretory cells of the insect corpus allatum (CA), thereby eliminating the

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Section: Metabolismmentioning

confidence: 99%

Precocene II Metabolism in Insects: Synthesis of Potential Metabolites and Identification of Initial in Vitro Biotransformation Products

Soderlund¹,

Messeguer²,

Bowers³

1980

J. Agric. Food Chem.

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“…In addition to their effects of limiting development and juvenile hormone secretion by the CA* (1-2, [6][7][8][9][10][11][12][13][14], nymphs of several species of insects fail to continue ecdysis and remain as permanent nymphs until death (1, 2, 6, 8, E-18). The mechanism by which exposure to precocene results in ecdysial stasis is unexplained.…”

Section: Introductionmentioning

confidence: 99%

“…The precocenes and their analogs are known to induce, in a number of insect species, morphogenetic effects that clearly result from the destruction of the corpus allatum (1)(2)(3)(4)(5). In addition to their effects of limiting development and juvenile hormone secretion by the CA* (1)(2)(6)(7)(8)(9)(10)(11)(12)(13)(14), nymphs of several species of insects fail to continue ecdysis and remain as permanent nymphs until death (1, 2, 6, 8, E-18). The mechanism by which exposure to precocene results in ecdysial stasis is unexplained.…”

Section: Introductionmentioning

confidence: 99%

Inhibition of ecdysteroid production in nymphs of Rhodnius prolixus treated with ethoxyprecocene II

Garcia

Feder

Bowers

1988

Arch Insect Biochem Physiol

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Rhodnius prolixus nymphs fed 7-ethoxyd-methoxy-2,2-dimethylchromene (ethoxyprecocene I I, EPII) show a variety of responses, including precocious molting to diminutive adults, severe retardation of molting, or a condition of permanent ecdysial stasis. The latter two conditions are reversible by subsequent treatment with 20-hydroxyecdysone. Ecdysteroid titers in the hemolymph of individual insects, determined by radioimmunoassay (RIA), show that the ecdysteroid cycle in nymphs undergoing precocious metamorphosis is similar to that of untreated fifth stage nymphs during normal imaginal molting. Nymphs in ecdysial stasis, following EPll treatment, were found to have very low ecdysteroid titers. Analysis of ecdysteroid synthesis by the prothoracic glands (PG), cultured in vitro, showed that: 1) only traces of ecdysteroid were detectable in PG from nymphs treated in vivo with EPII; 2) the PG from untreated nymphs incubated in culture medium with EPll possessed significantly lower ecdysteroid synthesis compared with controls. These studies sought t o determine if the inhibition of ecdysteroid biosynthesis observed in Rhodnius, following exposure to EPll in vivo and in vitro, is due to a direct action on the PG or result as an indirect effect perhaps mediated by the neuroendocrine system.

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Comparison of structurally analogous allatotoxins on the molting and morphogenesis of Rhodnius prolixus, and the reversal of ecdysial stasis by ecdysone

Garcia¹,

Bowers

1984

Arch Insect Biochem Physiol

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The allatotoxic effect of 3-ethoxy4methoxy-6iso-pentenylphenol o n nymphal molting and metamorphosis of Rhodnius prolixus was examined. Continuous contact treatment with IPP induced the formation of precocious adults and retarded molting or initiated a permanent ecdysial stasis. Insects treated with 7-ethoxy-6-methoxy-2,2-dimethylchromene were similarly affected. Ecdysone given orally counteracted the ecdysial stasis and also reduced the duration of the molting delay caused by IPP.Key words: Rhodnius prolixus, precocious metamorphosis, allatotoxin, antijuvenile hormone activity, ecdysial stasis, precocene, ecdysone INTRODUCTIONSince the discovery of the antijuvenile hormonal compounds precocene I and I1 [1,2] a significant body of literature has accumulated detailing the action of these compounds on insects [3-51. In general, these investigations show that the precocenes inhibit development of the corpus allatum [1,2,6-81 through an induced atrophy of its parenchymal cells [9-111. The degeneration of the gland and its subsequent invasion by connective tissue terminates JH* production in vivo [l-31 and in vitro [12-l5]. Morphogenetic, 'Abbreviations: Ethoxy precocene I I = 7-ethoxy-6-methoxy-2,2-dimethyl chromene = EPII; 3-ethoxy4methoxy-6-iso-pentenylphenol = IPP; juvenile hormone = JH; prothoracicotropic hormone = PTrH.Acknowledgments:

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In vitro inactivation of corpora allata of the bugOncopeltus fasciatus by precocene II

Cited by 25 publications

References 6 publications

Precocene II Metabolism in Insects: Synthesis of Potential Metabolites and Identification of Initial in Vitro Biotransformation Products

Precocene II Metabolism in Insects: Synthesis of Potential Metabolites and Identification of Initial in Vitro Biotransformation Products

Inhibition of ecdysteroid production in nymphs of Rhodnius prolixus treated with ethoxyprecocene II

Comparison of structurally analogous allatotoxins on the molting and morphogenesis of Rhodnius prolixus, and the reversal of ecdysial stasis by ecdysone

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