The aerobic aquatic soil metabolism of three ¹⁴C-labeled organophosphorus pesticides was examined in French lake water-sediment systems to estimate factors controlling their behavior in the natural aquatic environment. The more hydrophobic tolclofos-methyl and butamifos rapidly distributed between the aqueous and sediment phases even in the early stage of incubation, while partition of cyanophos to the sediment was found to be more gradual. The three pesticides were degraded in the water-sediment systems with half-lives of 8.8 to 24.5 days. Tolclofos-methyl and cyanophos commonly underwent cleavage of the P-O-methyl and P-O-aryl linkages the latter with a stepwise hydration of the cyano group, while butamifos was degraded to many unknown compounds each with less than 1.4% of the applied radioactivity. The evaporative loss of tolclofosmethyl and butamifos possibly due to azeotropic co-distillation was observed. The behavior of pesticides in the water-sediment system was considered to be mainly controlled by the balance among partition, degradation and evaporative processes, at least in part due to their chemical structures and physico-chemical properties.

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Thirty different antibiotics with various structures and modes of action were tested for effects on the formation of aerial mycelia in Streptomyces scabies, S. acidiscabies, and S. alboniger. Many antibiotics inhibiting protein synthesis suppressed the development of aerial mycelia at less than 10% of the concentration required for growth inhibition in substrate mycelia. Spectinomycin selectively prevented aerial mycelium formation without inhibiting substate mycelia in all strains tested. Chlortetracycline inhibited aerial mycelium formation in the pathogens causing potato scab, S. scabies and S. acidiscabies, but was ineffective in S. alboniger. In the two pathogenic strains, inhibition of aerial mycelia by spectinomycin and chlortetracycline decreased phytotoxin production substantially.

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Castasterone/ponasterone hybrid compound, (20R)-2α,3α,20, 22-tetrahydroxy-5α-cholestan-6-one, was newly synthesized from the corresponding α-alkoxystannane, in which the α-hydroxy group was protected with a benzyloxymethyl ether, and 6,6-ethylenedioxy-2α,3α-isopropylidenedioxy-5α-pregnan-20-one. The inhibition of the incorporation of [³H]ponasterone A into two insect cell lines was examined, and the concentrations of this hybrid compound required to give 50% inhibition were determined to be 0.29μM and 0.89μM for Kc and Sf-9 cells, respectively. This hybrid compound was 10 times more potent than ecdysone, but 100-200 times less potent than ponasterone A. The potency of this compound was equivalent to inokosterone against Sf-9 cells. The molting hormonal effect of this compound was also evaluated in the cultured integument system of the rice stem borer Chilo suppressalis for the induction of chitin synthesis, and the 50% effective concentration was determined to be about 10μM, equipotent to ecdysone.

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Four hydrazones (HZs) and six semicarbazones (SCZs) of substituted benzaldehydes were synthesized and examined for their ability to control insect adenylate cyclase through their interaction with biogenic amine receptors. Among the compounds synthesized, two with a hydroxyl group at the 4-position of the phenyl moiety, HZ-01 and SCZ-03, were found to reduce the basal levels of cAMP in head membrane homogenates of fifth instar larvae of the silkworm Bombyx mori. The semicarbazone SCZ-03 dose-dependently attenuated not only basal but also forskolin-stimulated cAMP levels. Tyramine (TYR) and dopamine (DPM) also produced a dose-dependent reduction in basal cAMP levels. DPM and TYR receptor antagonists abolished the attenuating effects of SCZ-03. These findings suggest that SCZ-03 acts as a non-selective agonist for DPM and TYR receptors to inactivate adenylate cyclase in B. mori larvae.

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Ipconazole is a triazole fungicide for treating rice seed. In the present study, degradation of ipconazole by isolated microorganisms from paddy soil was investigated. To enrich the degraders, the soil sample was perfused with ipconazole solution for 41 days. After the perfusion, the ipconazole-tolerant microbes in the perfused soil were cultivated on various media containing ipconazole. One bacterial, 12 actinomycetous, and 7 fungal strains showed ipconazole-degrading activity among 39 strains of bacteria, 14 strains of actinomycetes, and 14 strains of fungi in the liquid media containing 0.1 μg/ml ¹⁴C-ipconazole after 28 days of incubation. In particular, 8 strains of actinomycetes decomposed more than 90% of the ipconazole. The metabolism of ipconazole was investigated using two strains of actinomycetes, A1 and D16, with a higher level of degrading activity than the others. The isolates A1 and D16 were identified as Kitasatospora sp. and Streptomyces sp., respectively. A1 degraded more than 80% of the applied ipconazole after 3 days incubation in a liquid culture containing ¹⁴C-ipconazole at 1 μg/ml. D16 degraded approximately 20% of the applied ipconazole after 2 days, but more than 99% after 6 days of incubation. The primary metabolic reaction could be dominated by oxidation at either the carbon of the methine in the isopropyl group or the carbon of the benzylmethylene. A1 and D16 also possess the ability to oxidize the carbon of the methyl portion of the isopropyl group as well as that of the methylene portion of the cyclopentane ring. The polar metabolites in ethyl acetate extracts had increased by the end of incubation. 1,2,4-Triazole was detected as a water-soluble metabolite in the culture. There is little information available regarding microbial degradation of azole compounds, but our results suggest that some soil microorganisms contribute to the biodegradation of the triazole fungicide ipconazole in soil.

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