The degradation of mepanipyrim [N-(4-methyl-6-prop-1-ynylpyrimidin-2-yl)aniline] in two soils was studied under the laboratory conditions, using ¹⁴C-preparations labeled separately in the pyrimidine and the benzene rings. The half-lives of the parent compound in upland soils were 13 days and 3 months. The compound was degraded via pathways including elimination of the phenyl group, hydroxylation of the propynyl moiety, and hydroxylation at the benzene ring. The main degradation route was elimination of the phenyl group. The large portion of the resultant products was probably incorporated into the bound residues and a small part was further degraded to ¹⁴CO₂. ¹⁴C-Carbon dioxide evolved in the soils treated with both ¹⁴C-preparations. Under the flooded condition mepanipyrim was degraded rapidly, and a larger amount of bound residues was formed compared with the upland condition. The main degradation route in the flooded condition was the serial changes of the propynyl moiety. Mepanipyrim was hardly degraded in the sterilized soils under the upland condition, suggesting that it was microbially degraded in the soils. It is also observed that mepanipyrim was slowly degraded even in the sterilized soils under the flooded condition, suggesting that non-biological degradation also was involved in causing the decrease of mepanipyrim.

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Absorption, translocation and metabolism of mepanipyrim, N-(4-methyl-6-prop-1-ynylpyrimidin-2-yl)aniline in tomato seedlings were studied using ¹⁴C-preparations labeled separately in the pyrimidine and the benzene rings. When [¹⁴C]mepanipyrim was topically applied onto the leaf surface, most of the recovered radioactivity remained on the treated leaf. Unchanged mepanipyrim and a lot of metabolites were detected in the treated leaf. 2-[4-Methyl-6-(1-propynyl)pyrimidin-2-ylamino]-phenol (M-37), 4-[4-methyl-6-(1-propynyl)pyrimidin-2-ylamino]phenol (M-1), 1-(2-anilino-6-methylpyrimidin-4-yl)-2-propanol (M-31), and 4-methyl-6-(1-propynyl)pyrimidin-2-ylamine (M-41) were tentatively identified as major metabolites. M-37 and M-31 were mainly detected as several kinds of glycosides. When [¹⁴C]mepanipyrim was applied in an aqueous solution, the radioactivity in the seedlings increased with time, and 1-(2-anilino-6-methylpyrimidin-4-yl)-2-propanone (M-6) was also identified in the seedlings. A large amount of M-31 was detected in the seedlings when M-6 labeled with ¹⁴C was applied to seedlings in the same method as the parent compound. It is suggested that mepanipyrim is metabolized to M-31 via M-6.

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To define acaricidal mechanism of a new acaricidal AKD-2023 (2-acetoxy-3-n-dodecyl-1, 4-naphthoquinone) and its metabolite, DHN (2-hydroxy-3-n-dodecyl-1, 4-naphthoquinone), the effects of these compounds on the respiration of flight-muscle mitochondria isolated from house flies were investigated. The inhibitory potency of AKD-2023 for succinate and pyruvate oxidation activity was much less than that of DHN. This result suggested that the hydrolyzed metabolite, DHN is virtually biologically active and inhibits the respiration of mitochondria. It was also proved that the inhibition occurs at the complex III in mitochondrial electron transfer chain. On the basis of reduction kinetics of cytochromes b and c₁, the binding site was shown to be ubiquinol oxidation site (Q₀ center) of complex III, being different from that of other acaricides developed recently.

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Carpropamid {(1RS, 3SR)-2, 2-dichloro-N-[1-(4-chlorophenyl)ethyl]-1-ethyl-3-methylcyclopropanecarboxamide} strongly inhibited pigmentation in shaking culture as well as in agar plate culture of Pyricularia oryzae and Verticillium dahliae. White crystals were isolated from the extract of the cultures of wild type strains of P. oryzae and V. dahliae treated with carpropamid. Analytical data of the crystals obtained from a spot at Rf0.36 on the TLC plates coincided with those of scytalone. A large amount of scytalone and a small amount of vermelone accumulated in the culture treated with 10μg/ml of carpropamid, while 2-hydroxyjuglone was not detected in these analyses. When scytalone was added to the shaking culture of albino mutants of P. oryzae (P₂-alb), it promptly disappeared from the culture and the culture was pigmented to light brown. But scytalone remained in the culture if treated with carpropamid. Scytalone and vermelone administered beside the colony of P₂-alb on the agar plates were converted to black pigments but the pigmentation was inhibited by carpropamid. These results suggest that carpropamid inhibits dehydration of scytalone and vermelone in the fungal melanin biosynthesis.

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5-Aminolevulinic acid (ALA) at low concentrations increased cold resistance in rice seedlings. The pretreatment of rice seedlings by root-soaking with ALA solution at 0.1-1ppm reduced the ratio of leaf rolling and electrolyte leakage from leaf tissue after cold treatment. Thirty days after cold treatment at 5°C for 5 days, the plants treated with 1ppm ALA resulted in 85% survival ratio, 6.1 leaves per plant and 111.8mg dry weight per aerial part of seedling, while 65%, 5.9 and 65.0mg respectively in the control plants. The dry weight of seedlings treated with ALA increased 1.7 folds as compared to the control plants. These results are the first evidence that ALA has protective effects against cold stress in rice seedlings. Abscisic acid (ABA) and brassinolide (BR) also increased the cold resistance in our bioassay system. Protective effect of BR at 0.001ppm against cold stress was similar to that of ALA. However, protective effect of ABA was different from that of ALA in terms of the ratio of leaf rolling after cold stress. ABA protected young leaves rather than old ones, while ALA and BR were more effective on the protection of old leaves.

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A total of 27 analogues of the astigmatid mite sex pheromone, 2-hydroxy-6-methylbenzaldehyde (6-methylsalicylaldehyde), were prepared and their activities were determined against two species. Aleuroglyphus ovatus and Acarus immobilis. Four analogues, 2-methylbenzaldehyde, 2-methylacetophenone, 6-methylsalicylic acid and 2-methylbenzoic acid, evoked the pheromone activity against A. ovatus, among which 6-methylsalicylic acid and 2-methylbenzoic acid exhibited the same level of the activity as that of the pheromone. On the other hand, five substituted salicylaldehydes (3-isopropyl-6-methyl-, 6-ethyl-, 3-methyl-, 3-ethyl- and non-substituted) and 4-hydroxy-2-methylbenzaldehyde indicated the activity against A. immobilis, whose activities were one-tenth of that of the pheromone at the best. As a result, each species demonstrated the similar pheromone behavior upon exposure to the different set of analogues, other than to the natural pheromone.

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Cartap, the synthetic analog of nereistoxin, is known to act on the nicotinic acetylcholine receptorchannel (AChR). Effects of cartap on the neuronal nicotinic AChR of clonal rat phaeochromocytoma (PC12) cells were studied using a single-channel patch clamp method. When cartap was co-applied with acetylcholine, the single-channel openings were shortened and occurred in bursts separated by brief closures or gaps. The current amplitudes in the presence of cartap were virtually identical to those of currents induced by ACh only. Mean open time and burst duration were significantly decreased in the presence of cartap in a dose-dependent manner. These changes of single-channel kinetics result in a significant decrease in total charge carried through the open AChR explaining the suppressive effect of cartap on nicotinic AChR. Results suggest that cartap could act as an open channel blocker at the nicotinic AChR.

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A series of N-substituted 2-alkoxyimino-2-cyanoacetamide derivatives were synthesized and their fungicidal activities against cucumber downy mildew were assessed. Our studies of the structure-activity relationships revealed that fungicidal activity was the strongest when the substituents on the acetamide nitrogen were 4, 5-dihydroisoxazole groups. Among the compounds examined, 2-cyano-2-methoxy-imino-N-(5, 5-dimethyl-4, 5-dihydroisoxazol-3-yl)acetamide (28) was more active than the original lead compound, cymoxanil.

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N-p-Coumaroyloctopamine (PCO) was identified as an induced phenolic substance in potato (Solanum tuberosum) tuber disks which had been treated with a hyphal wall component from a blight fungus, Phytophthora infestans. The induction was also caused by treating the disks with laminarin, an algal β-1, 3-glucooligosaccharide, in a dose-dependent manner. Maximum level of induction was about 150μg (500nmol)/g tissue. A purified β-1, 3-glucosaccharide with a degree of polymerization of 7 was significantly active at 1.2mM, although the amount of induced amide was smaller than that induced by laminarin itself. The fatty acid elicitor, arachidonic acid, was not as effective for inducing PCO. This response of potato tuber disks may serve for elucidating the action mechanism of oligosaccharides that can modify plant secondary metabolism.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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