Publications by authors named "Mitsuru Hirota"

As plant distribution and performance are determined by both environmental and genetic factors, clarifying the contribution of these two factors is a key for understanding plant adaptation and predicting their distribution under ongoing global warming. is an ideal species for such research because of its wide distribution across diverse environments. Stomatal density and size are crucial traits that plants undergo changes in to adapt to different environments as these traits directly influence plant photosynthesis and transpiration.

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The reduced growth performance of individuals from range edges is a common phenomenon in various taxa, and considered to be an evolutionary factor that limits the species' range. However, most studies did not distinguish between two mechanisms that can lead to this reduction: genetic load and adaptive selection to harsh conditions. To address this lack of understanding, we investigated the climatic and genetic factors underlying the growth performance of Betula ermanii saplings transplanted from 11 populations including high-altitude edge and low-latitude edge population.

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As it is responsible for the second largest CO flux in the terrestrial ecosystem, the accurate estimation and prediction of soil respiration (SR) are necessary, especially for forest ecosystems, which are a major contributor to the total terrestrial SR. Spatial variation is one of the challenges affecting the accurate estimation and prediction of forest SR in ecosystems. Although a number of studies have examined spatial variation in SR within individual forests, the magnitude and patterns of spatial variation in SR within forest ecosystems (CV of SR [%]) remain unexplored at the global scale.

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The taxon Aspergillus section Fumigati comprises several causative agents of aspergillosis. Here, the distribution of Aspergillus sect. Fumigati in outdoor environments of Izu and Ogasawara Islands was investigated.

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Pioneer species differing in their inherent ecological characteristics (e.g., N-fixing ability, photosynthetic pathway) can have a large impact on local ecosystems in the early stages of volcanic succession.

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Forest understory plays an important role in the gross primary production (GPP) of some forest ecosystems. However, differences in understory GPP caused by obviously different overstory canopy structure have not been taken into consideration in previous studies, thus potentially over- or underestimating understory GPP. To estimate the understory GPP more accurately, we separated a forest into "canopy area", with closed-overstory canopy, and "gap area", with open-overstory canopy.

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How photosynthetic-related leaf traits of non-nitrogen (N)-fixing pioneer species respond to extreme habitat conditions of primary succession is still not well-elucidated, especially in volcanically N-deplete habitats. The effect of N-deplete soil on photosynthetic-related leaf traits can provide a basis for predicting how plants adjust their strategies to adapt to such habitats. To examine the responses of leaf traits to extreme conditions, we investigated (a non-N-fixing C pioneer grass) which grows on a volcanically devastated area on Miyake-jima Island, Japan, in which the volcanic ash has been deposited for 17-18 years since the 2000-year eruption.

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Excessive uric acid production, which causes gout and hyperuricemia, can be blocked by inhibiting xanthine oxidase (XO). However, some agents to block on XO often cause side effects, thereby necessitating the identification of new inhibitors. During the screening of XO inhibitors from various mushroom extracts, we found that a methanolic extract of the fruiting bodies of Tyromyces fissilis, an inedible and non-toxic fungus, showed inhibitory activity.

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Grifola frondosa is an edible mushroom consumed as a health food and/or traditional medicine in Asia. However, the anti-allergic effects of G. frondosa are not yet understood.

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The immunomodulatory effects of a hot water extract from matured fruit of the date palm tree (Phoenix dactylifera L.) were investigated in comparison to those of prune and fig fruit in mice. The number of spleen IFN-γ(+)CD4(+), IFN-γ(+)CD49b(+) and IL-12(+)CD11b(+) cells was highest in mice given the date extract-added diet.

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The ¹³C labels of [¹³C]carbon dioxide and D-[¹³C₆]glucose were incorporated into cyanamide (NH₂CN) when they were administered to Vicia villosa subsp. varia shoots. In contrast, the administration of sodium [2,3-¹³C₂]pyruvate did not affect the relative area of the [M + 1]+ ion of cyanamide in the gas chromatography-mass spectrometry analysis.

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Yb(OTf)(3)-catalyzed equimolar condensation of the benzylated catechin with various 4-alkoxy catechin derivatives was studied. In particular, the reaction using 4-(2''-ethoxyethoxy)flavan derivative gave good yield with excellent stereoselectivity. The condensed product was successfully converted to procyanidin B3 (1).

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Characterizing the spatial variation in the CO2 flux at both large and small scales is essential for precise estimation of an ecosystem's CO2 sink strength. However, little is known about small-scale CO2 flux variations in an ecosystem. We explored these variations in a Kobresia meadow ecosystem on the Qinghai-Tibetan plateau in relation to spatial variability in species composition and biomass.

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Stereoselective syntheses of daedalin A and quercinol, an enantiomer of daedalin A, is described. The tyrosinase inhibitory activities of daedalin A and quercinol were examined. The activity of quercinol was weaker than that of daedalin A at high concentration.

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A concise synthesis of (-)-epicatechin 3-(3-O-methylgallate) (1; ECG3''Me), which is a minor constituent of tea, and (+)-catechin 3-(3-O-methylgallate) (2; CG3''Me) via condensation of equimolar amount of catechin and gallate derivatives has been achieved. The anti-inflammatory effect of the synthetic compounds on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation of mouse ears was examined. Compounds 1 and 2 suppressed the TPA-induced inflammation of mouse ears by 50 and 43%, respectively, at a dose of 200 microg.

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The culture broth of Daedalea dickinsii was found to predominantly contain the tyrosinase inhibitor, (2R)-6-hydroxy-2-hydroxymethyl-2-methyl-2H-chromene, daedalin A (1). Ongoing research into bioactive metabolites resulted in the identification of two new 2H-chromenes, 6-hydroxy-5,7-dimethoxy-2,2-dimethyl-2H-chromene (3) and 6-hydroxy-2-hydroxymethyl-5-methoxy-2-methyl-2H-chromene (4), together with 6-hydroxy-2,2-dimethyl-2H-chromene (2). Comparative studies of isolated compounds 1-4 and related compounds (+/-)-1 and 1a-1c showed 1 to have the strongest tyrosinase inhibitory activity.

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There is an ongoing search for plant-derived diterpenes, especially for diterpenes with anti-inflammatory activity that also have anti-proliferative effects on human cancer cells. A cyathane-type diterpene, Sarcodonin G (SG), isolated from the mushroom Sarcodon scabrosus and already reported to have anti-inflammatory activity, inhibited proliferation of HeLa cells to the greatest extent among 4 cyathane diterpenes tested. SG showed an IC50 (50% inhibition concentration) of 20 microM, estimated by MTT assay 2 days after culture of cells with the chemical.

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Neurotrophic factors are essential to maintain and organize neurons functionally; thereby neurotrophic factor-like substances or their inducers are expected to be applied to the treatment of neurodegenerative diseases such as Alzheimer's disease. In the present study, we firstly examined the effects of ethanol extracts of four edible mushrooms, Hericium erinaceus (Yamabushitake), Pleurotus eryngii (Eringi), Grifola frondosa (Maitake), and Agaricus blazei (Himematsutake), on nerve growth factor (NGF) gene expression in 1321N1 human astrocytoma cells. Among the four mushroom extracts, only H.

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Cyanamide (NH2CN) has recently been proven to be a natural product, although it has been synthesized for over 100 years for agricultural and industrial purposes. The distribution of natural cyanamide appears to be limited, as indicated by our previous investigation of 101 weed species. In the present study, to investigate the distribution of natural cyanamide in Vicia species, we monitored the cyanamide contents in V.

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A chromene-type compound, daedalin A (1), was isolated from mycelial culture broth of Daedalea dickinsii. Based on spectroscopic data, the structure of 1 was found to be (2R)-6-hydroxy-2-hydroxymethyl-2-methyl-2H-chromene. Daedalin A (1) strongly inhibited the activity of tyrosinase (IC(50): 194 muM).

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We measured fluxes of carbon dioxide (CO(2)), methane (CH(4)), and nitrous oxide (N(2)O) simultaneously in two typical fringing zones, sandy shore and salt marsh, of coastal lagoon, Lake Nakaumi, Japan, in mid-summer 2003. Our aim was to quantify net the greenhouse gases (GHGs) fluxes and examine key factors, which control variation of the GHGs fluxes in the two sites. Net CO(2) and CH(4) fluxes were markedly different between the two sites; magnitudes and variations of the both fluxes in sandy shore were lower than those of salt marsh.

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A new lactarane sesquiterpene, 1,2-dehydrolactarolide A (1), together with lactarorufin A (2), 3-O-ethyllactarolide A (3) and 3-O-ethyllactarolide B (4), was isolated from a mushroom of the Russulaceae family, Lactarius vellereus. Additionally, two lactarane sesquiterpenes, lactarorufin A (2) and lactarolide A (5) were isolated from L. subpiperatus.

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Article Synopsis
  • Cyanamide (NH2CN) is a naturally occurring compound primarily recognized for its industrial use, and its presence in the plant kingdom was studied using a precise method called stable isotope dilution gas chromatography-mass spectrometry (SID-GC-MS).
  • The SID-GC-MS method successfully quantified cyanamide levels in 101 species of herbaceous plants, with an average recovery rate of about 55.6%.
  • Among the plants tested, only Vicia villosa and V. cracca showed significant cyanamide concentrations, while the other 99 species had undetectable levels, indicating that cyanamide distribution in plants is both limited and uneven.
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Three new plant growth regulatory sesquiterpenes were isolated from the Lactarius repraesentaneus fungus. Their structures were elucidated to be lactarane sesquiterpenes, namely repraesentins D (1) and E (2), and a protoilludane-related sesquiterpene, namely repraesentin F (3). Repraesentin E (2) showed the strongest promotion activity, 164% at 3.

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