The binding of [³H]abamectin was studied in susceptible and abamectin resistant strains of house fly, Musca domestica. There was a higher binding site density (B_max) and a higher dissociation constant (K_D) in the heads and thoracic ganglia compared to the thoraces without ganglia in both strains. The only difference between the resistant and susceptible strains was a small, but significant, decrease in the B_max found in the thoraces without ganglia. Picrotoxinin, dieldrin, muscimol, Ro5-4864 and 4-tert-butyl-1-(4-cyanophenyl)trioxabicyclo[2.2.2]-octane did not displace [³H]abamectin binding in the house fly suggesting the binding site of abamectin is unique and not the same as these other well characterized ligands. Abamectin resistance did not confer cross-resistance to the bicycloorthobenzoate insecticide 4-tert-butyl-1-(4-ethynylphenyl)trioxabicyclo[2.2.2]octane.

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The effect of chlorothalonil (Daconil^® 1000) application on cellulose decomposing process in soil, and the impact and duration of the effect were estimated in laboratory experiments at 25°C and 13°C under upland conditions. In the soil just after the application, the pesticide caused the retardation of cellulose decomposition and the shifts in the balance of fungal flora on the cellulose sheets at doses above 75μg a. i./g-soil at 25°C and at doses above 15μg a. i./g-soil (recommended rate of the pesticide for drenching) at 13°C. In the soil after 10 weeks of the application, no retardation in cellulose decomposition and incomplete recovery of the fungal flora were observed at doses of 75μg a. i./g-soil at 25°C. Relative dominance and frequency of a fungal species, Rhizoctonia solani, on the cellulose sheets at 13°C were high in the control soil but low in applied soil. The retardative effects of the chlorothalonil application on cellulose decomposition in the soils at low temperature seem to be attributable to reduction in the dominance of R. solani on the cellulose sheets. Since the species is one of the target pathogen for the drenching of chlorothalonil, the retardative effect on cellulose decomposition should be defined as a side-effect in respect of phenomenon, whereas, as a objective effect in respect of mechanism. These results represent the importance of research on the structure of microflora and consideration on the environmental condition such as temperature in assessment on effect of pesticide on soil ecosystem.

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Two atrazine-degrading bacteria, RK014 from Anjo (Japanese) soil and RK016 from Pak Chong (Thai) soil, were isolated. The isolate RK014 was an unidentified, Gram negative and non spore-forming rod, while RK016 was classified into Bacillus sp. The study on the degradation of atrazine in tenfold diluted nutrient broth containing 10mg/l of atrazine revealed that atrazine was degraded mainly at stationary phase in both bacterial cultures. Higher than 10⁸-10⁹cfu/ml of initial cell density was required for rapid degradation. The degradation rate of atrazine was higher at pH 8 than pH 5 in both cultures with the high density of inoculum. Deethylatrazine was a major metabolite by both isolates in the cultures. It is suggested that these characteristics of atrazine-degrading bacteria caused the slow microbial degradation of atrazine in soils in spite of ubiquitous presence of degrading microorganisms at 10⁵MPN/g-soil.

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The effects of various molecular probes on the dynamic behaviour of O^-·₂ generation and α-linolenate release from rice (Oryza sativa) blade tissue preparations with press-injured spot (2mm), pre-treated with the molecular probe and post-stimulated with blast fungus (Pyricularia oryzae) elicitor, were surveyed. Neomycin (1mM), an inhibitor on PI (phosphatidylinositol) turnover, inhibited two parameters. Using an immunoblotting assay to detect PIP₂ (phosphatidylinositol 4, 5-bisphosphate) in extracts of elicitor stimulated protoplasts, the disappearance or reappearance of PIP₂ were observed 1min or 10min after the stimulation. The press-injured blade disks treated with GTP-γ-S (guanosine-5′-O-(3-thiotriphosphate)) (1mM) shortened the time to maximum O^-·₂ generation and also activated O^-·₂ generation after elicitor stimulation. The press-injured blade disks applied with B. cereus phospholipase C generated O^-·₂. Using the stimulated protoplasts and a specific binding assay for IP₃ (inositol 1, 4, 5-trisphosphate), the maximum accumulation or the decline of IP₃ was observed 1min or 5min after the stimulation. The application of diltiazem, nifedipine or verapamil (10-100μM), potent inhibitors on an opening of calcium channels, strongly inhibited both parameters. The lines of evidence strongly bore out the suggestion that the phospholipase C system is operating in rice blade cells stimulated by blast fungus elicitor.

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3-Arylimino-5, 6-dihydro-3H-thiazolo[2, 3-c][1, 2, 4]thiadiazoles (III) were synthesized by oxidative ring closure of 3-(N-arylthiocarbamoyl)-2-iminothiazolidines. And this synthetic method was successfully applied to the synthesis of other 3-arylimino-1, 2, 4-thiadiazolo-fused heterocyclic systems. In foliage treatment this series of compounds exhibited fast-acting and light dependent herbicidal actions which are similar to those of diphenyl ethers and tetrahydrophthalimides. The potency of the herbicidal activity was found to depend on both the substituents on the benzene ring and heterocyclic moieties. Substituent effect of the benzene ring on the herbicidal activity was similar to that of tetrahydrophthalimides. Acid-catalyzed hydrolysis, base-catalyzed hydrolysis and photo-decomposition of III were also studied. Several products were isolated and their structures were determined. However any 1, 2, 4-triazole-3-thione derivative, which is known to exhibit herbicidal activity similar to that of tetrahydrophthalimides, was not isolated. Under such chemical conditions, the rearrangement of 3-arylimino-1, 2, 4-thiadiazolo-fused ring systems to form 2-aryl-3-thio-1, 2, 4-triazolo-fused ring systems seemed to be difficult.

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Pseudomonas glumae was isolated from the lower leaf sheaths, stem bases and roots up to maximum tiller number stage. P. glumae populations on the flag leaf sheaths and the 2nd leaf sheaths under the flag leaf sheaths increased during booting stage. And there was a remarkable increase in the bacterial population on spikelets during heading. The higher the number of P. glumae population on rice plants at maximum tiller number stage was, the higher the number of the bacterial population on the upper leaf sheaths and spikelets was. And the higher the number of the bacterial population on spikelets was, the severer bacterial grain rot of rice was. Treatment with oxolinic acid (5-ethyl-5, 8-dihydro-8-oxo[1, 3]dioxolo-[4, 5-g]quinoline-7-carboxylic acid, Starner^®) at heading stage inhibited an increase in the bacterial population on spikelets and was highly efficacious in the control of disease. These results suggest that disease severity depends on an increase in P. glumae population on spikelets during heading, and the bacterial population on spikelets is affected by the bacterial populations on the upper leaf sheaths at booting stage, and subsequently the bacterial population colonized on rice plants at maximum tiller number stage.

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The effects of molecular probes on the dynamic behaviours of O^-·₂ generation and α-linolenate release from rice (Oryza sativa) blade tissue preparations with press-injured spot (2mm), pre-treated with the molecular probes and post-stimulated with blast fungus (Pyricularia oryzae) elicitor, were further surveyed. Compound W-7 or ophiobolin A, potent inhibitors on the function of CaM (calmodulin), strongly inhibited both O^-·₂ generation at 10μM and α-linolenate release at 500μM after the elicitor stimulation. The comparative coupledenzymic analysis on the behaviour of free CaM in the healthy or infected rice blades with blast fungus conidia revealed an immediate decrease of free CaM by the infection. TPA (10μM), an agonist of diacylglycerol for proteinkinase C, did not activate both parameters with the elicitor stimulation, although TPA (10μM) markedly activated the α-linolenate release at the later phase with the stimulation. The application of H-7 (1mM) or staurosporin (10μM), unspecific inhibitors on proteinkinases, inhibited the O^-·₂ generation, but staurosporin (50μM) activated the α-linolenate release at the later phase and H-7 (1mM) inhibited the α-linolenate release after the elicitor stimulation. The application of 1, 2-benzisothiazol-3(2H)-one 1, 1-dioxide (1mM) with the elicitor stimulation further activated the O^-·₂ generation and markedly activated the α-linolenate release at the later phase. The lines of evidence strongly bore out the suggestion that the formations of Ca²⁺-MPs (Ca²⁺-calcium modulated proteins), which signal-coupled with the operation of phospholipase C system, play an indispensable role in activating rice blade O^-·₂ forming redox system and phospholipase A₂.

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The effect of a moisture content and UV irradiation on the degradation of the pyrethroid insecticide fenpropathrin (I) [(RS)-α-cyano-3-phenoxybenzyl 2, 2, 3, 3-tetramethylcyclopropanecarboxylate] on soil surfaces was examined using a xenon lamp (λ>290nm). I was rapidly degraded at a lower moisture content of soil via hydration of the α-cyano group and UV irradiation was found to slightly facilitate the degradation. As with an increase of moisture, the degradation pathways previously reported in aerobic and anaerobic soil metabolism became predominant on the soil surfaces. The marked change of a surface acidity of clay with a moisture content was likely to account for the moisture dependency of the degradation.

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Hydrolysis of a pyrethroid insecticide trans-tetramethrin (I) [3, 4, 5, 6-tetrahydrophthalimidomethyl (1RS)-trans-chrysanthemate] was examined at 25±1°C, using the ¹⁴C preparations labeled at 1-position of the cyclopropyl ring or at 1- and 2-positions of the 3, 4, 5, 6-tetrahydrophthalimido moiety. HPLC analysis of the buffered aqueous solutions showed that I was degraded following pseudo-first-order kinetics at pH 5.0 with a rate of 4.08-4.99×10^-7 sec^-1, while it was rapidly hydrolyzed with initial rates of 7.82-8.75×10^-6 sec^-1 at pH 7 and 6.02-8.62×10^-4 sec^-1 at pH 9, followed by slower hydrolysis. HPLC and TLC cochromatographies with synthetic standards and LC-MS analysis showed that I was primarily hydrolyzed to the unstable tetrahydrophthalamic acid derivative of I via opening of the cyclic imido moiety. The ester linkage was subsequently cleaved to form trans-chrysanthemic acid and the unstable N-hydroxymethyl 3, 4, 5, 6-tetrahydrophthalamic acid. The latter amic acid was stepwisely hydrolyzed by liberating formaldehyde to 3, 4, 5, 6-tetrahydrophthalic acid via its amide derivative.

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Two soil bacteria, Bacillus sp. B75 and an unidentified Gram-variable rod B116, degraded 1, 1, 1-trichloro-2, 2-bis(4-chlorophenyl)ethane (DDT) at extremely low concentration levels in the range of 10pg/ml to 100ng/ml in one-tenth diluted nutrient broth. Higher than 88% of DDT was degraded after 2 weeks of incubation. The metabolites produced, 1, 1-dichloro-2, 2-bis(4-chlorophenyl)ethylene, 1, 1-dichloro-2, 2-bis(4-chlorophenyl)ethane and other acetone/hexane-extractable compounds, and their proportion were identical between 160pg/ml and 100ng/ml of DDT concentration levels except for the different proportion of metabolites in the B116 culture. A large part of DDT was sorbed to both bacterial cells in 48hr even at extremely low concentration levels, suggesting that the uptake rate of DDT by the bacteria does not limit the degradation rate. These findings indicate that there is no threshold concentration for bacterial degradation of DDT under the presence of other carbon and energy sources.

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Various trichloromethyl-1, 3, 5-triazines were synthesized and effects of trichloromethyl-1, 3, 5-triazines on nitrification in the upland soil were investigated. 2-Substituted-4, 6-bis(trichloromethyl)-1, 3, 5-triazines were prepared by trimerization or cotrimerization using CCl₃CN in the presence of Norton-Wakabayashi complex catalyst, e. g. AlBr₃-HCl. 2-Amino-4-substituted-6-trichloromethyl-1, 3, 5-triazines were obtained through the haloform type of reactions of trichloromethyl-1, 3, 5-triazines with amines. The pI₅₀ values of highly active trichloromethyl-1, 3, 5-triazines were 4.5-5.5. Essentially they have a CCl₃-group and an amino or alkylamino group in the three substituents of 1, 3, 5-triazine ring. QSAR between pI₅₀ values and log P(S) parameters were investigated by multi-parameter regression analysis. Hydrophobic parameters, log P(S) estimated by semi-empirical calculation, were used for convenience instead of log P(H) determined by HPLC in this QSAR study. The optimum log P(S) was calculated as 2.91, a little more hydrophobic figure compared with the log P value (ca. 2.4) in our previous paper. By the use of this value, it will become possible to design highly active trichloromethyl-1, 3, 5-triazine nitrification inhibitors.

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Using Scenedesmus acutus and Echinochloa utilis, a series of isomeric compounds, namely thiadiazolidines and triazolidines, were assayed with respect to decrease of chlorophyll contents, protoporphyrin-IX accumulation, light-induced ethane formation levels. The both types of phytotoxic compounds decreased chlorophyll contents, caused protoporphyrin-IX accumulation and ethane evolution, and inhibited growth of Scenedesmus cells, just like the so-called peroxidizing herbicides such as p-nitrodiphenyl ethers and cyclic imides. Correlations between the phytotoxic parameters were highly significant. Our comparative data on different sets of the parameters suggest that both the thiadiazolidine and triazolidine herbicides are classified as peroxidizing herbicides, affecting a crucial enzyme in the chlorophyll biosynthesis and inducing ethane formation by the light induced radicals.

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New Imidazole fungicides, OK-8705 (1-(4-methoxyphenoxymethyl)-2, 2-dimethylpropyl imidazole-1-carboxylate) and OK-8801 (the thiocarboxylate derivative of OK-8705), have one chiral center in the molecule. We determined the absolute configurations of the common starting material for synthesis of the fungicides, (-)- and (+)-1-(4-methoxyphenoxy)-3, 3-dimethyl-2-butanol, as (R)- and (S)-enantiomers, respectively, by Mosher's method. (R)- and (S)-OK-8705 and OK-8801 prepared from the (R)- and (S)-alcohols, respectively, were evaluated for their antifungal activity against Botrytis cinerea and Gibberella fujikuyoi using the agar dilution method. The antifungal activities of the (R)-isomers of OK-8705 and OK-8801 against B. cinerea were 513 and 265 times higher than those of the (S)-isomers, respectively; against G. fujikuyoi 38 and 143 times higher, respectively. We concluded that the (R)isomers were mainly responsible for the antifungal activity.

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[in Japanese]

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