Protoporphyrinogen IX-oxidizing activities involved in the mode of action of a new compound N-[4-chloro-2-fluoro-5-{3-(2-fluorophenyl)-5-methyl-4,5-dihydroisoxazol-5-yl-methoxy}-phenyl]-3,4,5,6-tetrahydrophthalimide

N-[4-Chloro-2-fluoro-5-{3-(2-fluorophenyl)-5-methyl-4,5-dihydroisoxazol-5-yl-methoxy}-phenyl]-3,4,5,6-tetrahydrophthalimide (EK-5385) is an experimental substituted bicyclic herbicide. Soil-applied EK-5385 showed good rice selectivity and potent herbicidal activity on barnyardgrass (Echinochloa crus-galli var. oryzicola) at rates of 3.9-250 g a.i./ha. Barnyardgrass was exhibited normal growth under dark condition, however, the growth of shoot and root was severely inhibited under light condition (14/10 h of light/dark, 50 μmol/m²/s of photosynthetically active radiation) when treated with EK-5385, oxadiazon, and oxadiargyl. IC₅₀ of EK-5385 and oxadiargyl to chlorophyll loss in cucumber cotyledons was approximately 0.3 and 0.7 μM, respectively. IC₅₀ of EK-5385 and oxadiargyl to carotenoids loss in cucumber cotyledons was about 0.26 and 0.1 μM, respectively. IC₅₀ concentration of EK-5385 and oxadiargyl on Protox activity was approximately 5.5 and 8 nM, respectively. Cellular leakage occurred without lag period from cucumber leaf squares treated with 1 μM of EK-5385 and oxadiargyl under light exposure.     

Aster yellows subgroup (Candidatus Phytoplasma sp. AY 16S-group,AY-sg) phytoplasma associated with porcelain vine showing witches' broom symptoms in South Korea

 This is the first report of a phytoplasma in porcelain vine [Ampelopsis brevipedunculata var. heterophylla (Thunb.) Hara.] with severe witches' broom symptoms in Korea. On the basis of the polymerase chain reaction-amplified ribosomal DNA, the phytoplasma infecting porcelain vine was classified as a member of the aster yellows subgroup. Received: October 21, 2002 / Accepted: December 20, 2002     

P-52 A case of juvenile cellulitis concurrent with hindlimb paresis in an English cocker spaniel puppy

Pemphigus vegetans is a very rare cutaneous autoimmune blistering acantholytic disease of humans that combines features of both pemphigus foliaceus and mucosal lesions of pemphigus vulgaris. We report here the clinical, histopathological and immunological findings in a dog whose lesions resembled those of pemphigus vegetans of humans. A 4-year old, greater Swiss mountain dog was presented with verrucous papules and crusts on the axillae and inguinal region. Within 3 months, lesions progressed to involve the thorax and ear pinnae, and then became generalized. Ulcers were observed in the oral cavity, anus and prepuce. Microscopic examination of mucosal and cutaneous biopsy specimens revealed a mixed pattern of deep intraepidermal neutrophilic and eosinophilic pustules with isolated and clustered acantholytic keratinocytes, along with suprabasal epidermal clefts leaving rounded basal keratinocytes at the bottom of the vesicles. These dual changes were also observed within the hair follicle epithelium. Dermal inflammation was mixed and perivascular. Direct immunofluorescence revealed IgG deposited around epidermal keratinocytes. Indirect immunofluorescence performed on normal canine gingival substrate uncovered antikeratinocyte IgG autoantibodies with a serum titre of 1:2500. Immunoblotting confirmed that circulating IgG autoantibodies recognized the extracellular segment of canine desmoglein-1 and human desmoglein-3. Treatment with azathioprine and oral glucocorticoids resulted in long-lasting complete remission. In this dog, clinical signs, microscopic skin lesions and immunological findings were deemed analogous to those of human Neumann-type pemphigus vegetans.
Funding: Self-funded.     

Guanidinium and amidinium fungicides: A new class of carbocation mimetic ergosterol biosynthesis inhibitors

A novel class of chemical has been designed with the aim of inhibiting the Δ¹⁴-reductase and Δ⁸-Δ⁷-isomerase enzymes in the ergosterol biosynthesis pathway in fungi. Use was made of knowledge about the mechanisms of both enzymes and the mode of action of known, fungicidal inhibitors of these enzymes. Pioneer examples have been synthesised and have been demonstrated to be potent inhibitors of ergosterol biosynthesis in Ustilago maydis (DC) Corda, acting in the same manner as the commercial fungicide fenpropimorph. They also showed excellent fungicidal activity against Erysiphe graminis DC f. sp. hordei Marchal (powdery mildew of barley) and Puccinia recondita Rob. ex Desm. (wheat leaf rust) in in-vivo glasshouse tests. Using these compounds as a starting point, systematic structural variation has been carried out. Testing of a wide range of analogues at high volume confirms the potential of this class of compound to control mildew and rust pathogens at levels comparable to those of the standards. Correlation of in-vivo and enzymatic data is good and the structure-activity relationship developed for this series of compounds closely parallels that found for the morpholine/piperidine class of fungicides, suggesting a common mode of action.     

An effective biocontrol bioformulation against Phytophthora blight of pepper using growth mixtures of combined chitinolytic bacteria under different field conditions

Phytophthora blight of pepper caused by Phytophthora capsici has devastating consequences when combined with other pathogens, including Rhizoctonia solani, Fusarium oxysporum, and Fusarium solani. In order to develop a field-effective biocontrol strategy against Phytophthora blight of pepper, three chitinolytic bacteria, Serratia plymuthica strain C-1, strongly antagonistic to P. capsici, Chromobacterium sp. strain C-61, strongly antagonistic to R. solani, and Lysobacter enzymogenes strain C-3, antagonistic to R. solani and Fusarium spp., were selected. In pot studies, application of cultures combining the three bacterial strains effectively suppressed Phytophthora blight more than application of any single bacterial strain. Bioformulations developed from growth of the strains in a simple medium containing chitin under large batch conditions resulted in effective control in field applications. Efficacy of the bioformulated product depended on both the dose and timing of application. Although the undiluted product suppressed Phytophthora blight under all field conditions, a 10-fold diluted product was effective in solar-sterilized greenhouses and in fields with crop rotation. These results suggest that the developed product could be a new effective system to control Phytophthora blight disease in pepper.     

Reassessment of vegetative compatibility of Sclerotinia homoeocarpa using nitrate-nonutilizing mutants

Nitrate-nonutilizing (nit) mutants were recovered for the first time from 21 isolates of Sclerotinia homoeocarpa collected in the United States. Mutants were selected from shredded mycelium of each isolate when cultured on water agar medium amended with 4% (wt/vol) potassium chlorate. The mutants could be classified into three phenotypes: nit1, nit3, and NitM, based on their growth on minimal medium (Czapek solution agar) supplemented with NaNO(2) or hypoxanthine. Complementary heterokaryons were observed in pairings between different phenotypes of nit mutants derived from compatible isolates, but not in self-fusions or pairings between incompatible isolates. The vigor of prototrophic growth varied with isolates and mutant phenotypes. Strong and continuous heterokaryons, as well as weak and spontaneous ones, formed depending on pairings of nit mutants. Stable heterokaryons between compatible isolates, but apoptotic reactions between incompatible isolates, were observed immediately after hyphal fusion under the epifluorescence microscope. The 21 isolates used in this study, which were previously assigned into 11 different vegetative compatibility groups (VCGs) based on the formation of a barrage zone at the contact site of paired isolates on complete medium (potato dextrose agar), were regrouped into five VCGs based on heterokaryon formation between nit mutants on minimal medium.     

Promising antidiabetic potential of fucoxanthin isolated from the edible brown algae Eisenia bicyclis and Undaria pinnatifida

In the present study, we investigated the antidiabetic potential of fucoxanthin via the inhibition of rat lens aldose reductase (RLAR), human recombinant aldose reductase (HRAR), advanced glycation end-product (AGE) formation, protein tyrosine phosphatase 1B (PTP1B), and α-glucosidase. Fucoxanthin displayed potent inhibitory activity against AGE formation and HRAR and RLAR activity. In addition, fucoxanthin showed potent inhibitory activity against PTP1B. However, it did not show α-glucosidase inhibitory activity below 200 μM. In addition, our kinetic study revealed that fucoxanthin competitively inhibited RLAR, while it showed mixed-type inhibition against PTP1B. In order to confirm enzyme inhibition, we predicted the 3D structure of PTP1B using Autodock 4.0 to simulate the binding of fucoxanthin. Docking simulation results demonstrated that three residues of PTP1B (Phe30, Phe52, and Gly183) interact with the two hydroxyl groups of fucoxanthin. In addition, the binding energy was negative (?7.66 kcal/mol), indicating that the three hydrogen bonds may stabilize the open form of the enzyme and potentiate tighter binding to the active site of PTP1B, resulting in more effective PTP1B inhibition. The results of the present study therefore clearly demonstrate the promising potential of fucoxanthin as a therapeutic intervention for the management of diabetes as well as diabetes-associated complications, which could be explored further.