Publications by authors named "Kodama O"

Congenital ventricular diverticulum is a rare anomaly with an unclear pathology. Here, we report a male fetus at 24 weeks of gestation, diagnosed with right ventricular diverticulum associated with tetralogy of Fallot and absent pulmonary valve. The diverticulum was located at the anterosuperior wall of the right ventricle and faced into the massive pulmonary regurgitation flow jet.

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An elicitor of rice defense responses was recently isolated from human feces and was identified as cholic acid (CA). Pathogen infection in rice leaves induces phytocassanes and momilactones, both of which are major diterpenoid phytoalexins in rice, whereas CA mainly induces phytocassanes. We established a high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry protocol for the rapid and accurate quantification of phytocassanes and momilactones.

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Rice diterpenoid phytoalexins such as momilactones and phytocassanes are produced in suspension-cultured rice cells treated with a chitin oligosaccharide elicitor and in rice leaves irradiated with UV light. The common substrate geranylgeranyl diphosphate is converted into diterpene hydrocarbon precursors via a two-step sequential cyclization and then into the bioactive phytoalexins via several oxidation steps. It has been suggested that microsomal cytochrome P-450 monooxygenases (P-450s) are involved in the downstream oxidation of the diterpene hydrocarbons leading to the phytoalexins and that a dehydrogenase is involved in momilactone biosynthesis.

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The jasmonic acid (JA)-responsive gene RERJ1 isolated from suspension-cultured rice cells encodes a transcription factor with a basic helix-loop-helix motif. In this study, we found that RERJ1 is also expressed in rice plants in response to JA, and that its expression in rice leaves is up-regulated by exposure to wounding and drought stress. It is also suggested that JA but not abscisic acid is involved in the up-regulation of RERJ1 expression caused by wounding and drought stress.

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Coronatine (1), its synthetic analogs (6-13) and jasmonic acid induced various volatiles in rice leaves. In the range of 0.01-0.

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Several types of jasomonic acid (JA) derivatives, including JA--amino acid conjugates, a JA--biotin conjugate, a JA--dexamethasone heterodimer, and a JA-fluoresceine conjugate, were prepared as candidates for molecular probes to identify JA--binding proteins. These JA derivatives, excepting the JA--fluoresceine conjugate, exhibited significant biological activities in a rice seedling assay, a rice phytoalexin-inducing assay, and/or a soybean phenylalanine ammonia-lyase-inducing assay. These JA derivatives could therefore be useful probes for identifying JA--binding proteins.

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Plant-derived essential oils with monoterpenoids have been used as antifungal drugs since ancient times, but the mode of action of these natural hydrocarbons at the molecular level is not understood. In order to understand the mechanisms of toxicity of alpha-terpinene (a cyclic monoterpene), a culture of Saccharomyces cerevisiae was exposed to 0.02% alpha-terpinene for 2 h and transcript profiles were obtained using yeast DNA arrays.

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The rice Oryza sativa selenium-binding protein homologue (OsSBP) gene encodes a homologue of mammalian selenium-binding proteins, and it has been isolated as one of the genes induced by treating a plant with a cerebroside elicitor from rice blast fungus. The possible role of OsSBP in plant defense was evaluated by using a transgenic approach. Plants overexpressing OsSBP showed enhanced resistance to a virulent strain of rice blast fungus as well as to rice bacterial blight.

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The volatiles released from elicitor (copper chloride, jasmonic acid, UV, L-methionine and chitosan oligomer)-treated and rice blast fungus-inoculated rice leaves were collected by the solid-phase microextraction technique and analyzed by GC-MS. (Z)-3-Hexen-1-ol, monoterpenes, methyl salicylate, and sesquiterpenes were identified as elicitor-induced volatiles by a comparison of their GC retention times and mass spectra with those of authentic compounds. The different elicitors resulted in some qualitative and quantitative differences in the production of volatiles.

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Both the (17R)- and (17S)-isomers of volicitin, which is contained in the oral secretion of the beet armyworm and induces corn seedlings to emit a blend of volatile compounds to attract the natural enemy of the herbivore, were synthesized via the semi-hydrogenation of an intermediary diyne and (Z)-selective olefination as the key steps. They were both obtained as crystalline compounds.

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Momilactone A, a major rice diterpene phytoalexin, could be synthesized by dehydrogenation at the 3-position of 3beta-hydroxy-9beta-pimara-7,15-dien-19,6beta-olide in rice leaves. The presence of 3beta-hydroxy-9beta-pimara-7,15-dien-19,6beta-olide in UV-irradiated rice leaves was confirmed by comparing the mass spectra and retention times after a GC/MS analysis of the natural and synthetic compounds. The soluble protein fraction from UV-irradiated rice leaves showed dehydrogenase activity to convert 3beta-hydroxy-9beta-pimara-7,15-dien-19,6beta-olide into momilactone A.

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Accumulation of 2-(2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one)-beta-D-glucopyranose (HDMBOA-Glc) was induced in maize leaves by treatment with CuCl2, chitopentaose, penta-N-acetylchitopentaose, or jasmonic acid (JA). The accumulation of HDMBOA-Glc was accompanied by a decrease in level of 2-(2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one)-beta-D-glucopyranose (DIMBOA-Glc). When the leaf segments were treated with JA in the presence of [Me-2H3]L-methionine, the label was efficiently incorporated into HDMBOA-Glc, while no incorporation into DIMBOA-Glc or HMBOA-Glc was detected, suggesting the conversion of constitutive DIMBOA-Glc to HDMBOA-Glc by methylation at the 4-position.

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All of the four possible stereoisomers of 5,9-dimethylpentadecane, the major sex pheromone component of the coffee leaf miner moth (Perileucoptera coffeella), were synthesized by using the methyl esters of (S)- and (R)-3-hydroxy-2-methylpropanoic acid as chiral sources for the purpose of determining the stereochemistry of the pheromone.

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Each stereoisomeric mixture of 5,9-dimethylpentadecane and 5,9-dimethylhexadecane, the major and the minor sex pheromone components of Perileucoptera coffeella, respectively, was synthesized in about 25% overall yield through 6 steps from beta-citronellol. 5,9-Dimethylheptadecane, the major sex pheromone component of Leucoptera malifoliella, was also synthesized analogously as a stereoisomeric mixture in a 22% overall yield.

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Production of reactive oxygen intermediates (ROI) and a form of programmed cell death called hypersensitive response (HR) are often associated with disease resistance of plants. We have previously shown that the Rac homolog of rice, OsRac1, is a regulator of ROI production and cell death in rice. Here we show that the constitutively active OsRac1 (i) causes HR-like responses and greatly reduces disease lesions against a virulent race of the rice blast fungus; (ii) causes resistance against a virulent race of bacterial blight; and (iii) causes enhanced production of a phytoalexin and alters expression of defense-related genes.

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The phytotoxin coronatine induced the accumulation of the flavonoid phytoalexins sakuranetin and momilactone A in rice leaves. Coronatine-inducible sakuranetin production was under the control of kinetin and ascorbic acid (AsA), as observed with jasmonic acid (JA). The effects of kinetin and AsA on the activity of coronatine indicated that coronatine might elicit sakuranetin production in a manner similar to JA.

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An inducible S-adenosyl-L-methionine:naringenin 7-O-methyltransferase (NOMT) catalyzing the methylation of naringenin to sakuranetin, a major rice phytoalexin was purified approximately 985-fold from ultraviolet (UV)-irradiated rice leaves. The enzyme is not found in healthy tissues and was purified to a nearly homogeneous preparation in one step using adenosine-agarose affinity chromatography, with 1 g rice leaves (UV-irradiated) as starting material. Gel filtration chromatography resulted in an almost pure enzyme, as evidenced by a major band migrating to a position corresponding to a molecular mass of approximately 41 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis.

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(-)-Periplanones C and D were obtained in reproducible yields by modifying reported procedures. Our synthetic sample of (-)-periplanone D showed somewhat different physical and spectroscopic properties from those reported in the literature.

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The application of methionine on wounded rice leaves induced the production of rice phytoalexins, sakuranetin and momilactone A. This induction resulted from stimulation of phenylalanine ammonia-lyase and naringenin 7-O-methyltransferase activity. Jasmonic acid, ethylene, and active oxygen species are important as signal transducers in disease resistance mechanisms.

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We screened 93 lesion mimic mutants of rice for resistance to the blast fungus, Magnaporthe grisea, and found eight mutants that exhibited significant resistance to the fungus. We called these mutants cdr (cell death and resistance) and further analyzed three of them. Two mutations, cdr1 and cdr2, were recessive and one, Cdr3, was dominant.

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Momilactones A and B in rice straw harvested at different growth stages were quantified by HPLC-MS-MS. They increased to their maximal levels at the heading stage and then gradually decreased. In addition, these phytotoxins were found to be relatively easily extracted with water.

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Three cases of rare intra-abdominal complications of ventriculoperitoneal shunt (VPS) surgery are reported. Case 1 was a 32-year-old male who had undergone VPS surgery for hydrocephalus following meningitis on July 10, 1980. Two weeks later he developed fever and a cystic mass about 10 cm in diameter in the right hypochondrium.

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Both enantiomers of 15-hexadecanolide, a sex pheromone component of the stink bug (Piezodorus hybneri), were synthesized by using the Yamaguchi or Mitsunobu macrolactonization reaction of (R)-15-hydroxyhexadecanoic acid prepared from ethyl (R)-β-hydroxybutyrate in 5 steps.

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Jasmonic acid (JA) has been shown to be a signaling compound which elicits the production of secondary metabolites including phytoalexins in plants. It has been shown that the phytoalexin production is elicited by exogenously applied JA in rice leaves. We now show that this phytoalexin production by exogenously applied JA is significantly counteracted by cytokinins, kinetin and zeatin.

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