研究者詳細 - 山崎　秀雄

論文 - 山崎　秀雄

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Occurrence and recent long-distance dispersal of deep-sea hydrothermal vent shrimps

Gaku Tokuda, Akinori Yamada,, Kazuma Nakano, Nao Arita, Hideo Yamasak

BIOLOGY LETTERS 2 257 - 260 2006年06月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Deep-sea hydrothermal vents and methane seeps are extreme environments that have a high concentration of hydrogen sulphide. However, abundant unique invertebrates including shrimps of the family Bresiliidae have been found in such environments. The bresiliid shrimps are believed to have radiated in the Miocene (less than 20 Myr); however, the period when and the mechanisms by which they dispersed across the hydrothermal vents and cold seeps in oceans worldwide have not been clarified. In the present study, we collected the deep-sea blind shrimp #IAlvinocaris longirostris#IR from the hydrothermal vent site in the Okinawa Trough and carried out the first investigation of the 18S rRNA gene of a bresiliid shrimp. The phylogenetic analysis revealed that the bresiliid shrimp is situated at an intermediate lineage within the infraorder Caridea and shows monophyly with palaemonid shrimps, which live in shallow sea and freshwater. Furthermore, the mitochondrial cytochrome oxidase I (#ICOI#IR) gene sequences were analysed to determine the phylogenetic relationship with known bresiliid shrimps. #IA. longirostris#IR of the Okinawa Trough had two haplotypes of the #ICOI#IR gene, one of which was identical to the #IAlvinocaris#IR sp. of the cold seeps in Sagami Bay. These results indicate that a long-distance dispersal of A. longirostris occurred possibly within the last 100 000 years.

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一酸化窒素（ＮＯ）発生の蛍光試薬による生体観察法

徳田岳, 有田奈央, 山崎秀雄

沖縄生物学会誌 44 2138 - 2144 2006年03月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Nitric oxide (NO) has been known as one of the toxic air pollutants NOx. Recent studies have evaluated that NO is endogenously produced through enzymatic activities in vertebrate animals. NO production similar to vertebrates has also been found in bacteria, fungi, algae, plants, and invertebrates, suggesting that NO is actually an essential molecule for living organisms. It is thus expected that NO also plays important roles in physiology of diverse living organisms in Ryukyu archipelago. However, our understanding on NO biology is yet too premature to account for diverse actions of this molecule. For studies of NO biology, technique(s) for detecting in vivo NO production is essential. In this paper we have reviewed a fluorometric method that has been recently developed for NO detection in vivo..

A simple method for two-dimensional color analyses of plant leaves

Shimoji H, Tokuda G, Tanaka Y, Moshiri B, Yamasaki H

RUSSIAN JOURNAL OF PLANT PHYSIOLOGY ( その他の出版社 ) 53 ( 1 ) 126 - 133 2006年01月

掲載種別: 研究論文（学術雑誌）

Coloration and color pattern are basic information for plant physiology, ecology, and taxonomy. Until recently, such color analysis of biological materials required expensive equipment. Here we report a convenient method for analyzing color of plant leaves with ImageJ, free software. Color digital images of croton leaves were divided with ImageJ into Red, Green, and Blue images, and then exported as two-dimensional numeric data. After processing images with Adobe Photoshop Elements and Microsoft Excel, color patterns were obtained as histograms. A comparison of the histograms evaluated characteristics of croton leaf variegation. The method successfully quantified color information of the plant leaves with an inexpensive PC set. Apart from taxonomic applications, the simple algorithms allow application of the present methodology to various types of color and color pattern analyses.

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Nitrogen oxidation in bacterium-plant interactions

Cohen MF, Mazzola M, Yamasaki H

Microbe 8 347 - 347 2006年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Requirement of water-flow for sustainable growth of Pocilloporid corals during high temperature periods

Nakamura T, Yamasaki H

MARINE POLLUTION BULLETIN ( その他の出版社 ) 50 ( 10 ) 1115 - 1120 2005年10月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Reef-building corals are threatened worldwide by mass-scale coral bleaching episodes that are pronounced in high sea surface temperature (SST) conditions. Although water-flow has been suggested to be a mitigating factor for bleaching, long-term effects of flow-mediated bleaching suppression are as yet not fully understood. In order to investigate flow effects, we monitored the corals #IPocillopora damicornis#IR and #IStylophora pistillata#IR grown for 20 months in experimental outdoor flumes with the flow rates of 20 cm s#U−1#UR (flow) and <3 cm s#U−1#UR (still). Although bleaching was observed under high SST conditions, both species showed a shorter period or entirely no visible bleaching under the flow conditions. Better colony growth was found in the flow conditions whereas significant growth suppression and higher mortality were observed in still conditions. We conclude that water-flow is an essential environmental factor for the corals #IP. damicornis#IR and #IS. pistillata#IR, especially under high SST conditions.

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Brassica napus seed meal soil amendment modifies microbial community structure, nitric oxide production and incidence of Rhizoctonia root rot

Michael F Cohen, Hideo Yamasaki, Mark Mozzola

SOIL BIOLOGY & BIOCHEMISTRY ( その他の出版社 ) 37 ( 7 ) 1215 - 1227 2005年07月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

A low glucosinolate content (21.8 μmol g#U−1#UR) #IBrassica napus#IR seed meal (RSM) applied to orchard soils altered communities of both pathogenic and saprophytic soil micro-organisms. RSM amendment reduced infection by native and introduced isolates of #IRhizoctonia#IR spp. and recovery of #IPratylenchus#IR spp. from apple roots. Root infection by #IRhizoctonia solan#IRi AG-5 was also suppressed in split-root assays where a portion of the root system was cultivated in RSM-amended soils and the remainder grown in the presence of the pathogen but lacking RSM. #IR. solani#IR hyphal growth was not inhibited by RSM amendment. Suppression of #IPratylenchus#IR was attained to an equivalent extent by amending soils with either RSM or soybean meal (SM) when applied to provide a similar N content. Thus, glucosinolate hydrolysis products did not appear to have a significant role in the suppression of #IRhizoctonia#IR spp. or #IPratylenchus#IR spp. obtained via RSM amendment. RSM amendment elevated populations of #IPythium#IR spp. and of ammonia-oxidizing bacteria that release nitric oxide but suppressed fluorescent pseudomonad numbers. #IStreptomyces#IR spp. soil populations increased significantly in response to RSM but not SM amendment. The vast majority of #IStreptomyces#IR spp. recovered from the apple rhizosphere produced nitric oxide and possessed a nitric oxide synthase homolog. We propose that transformations in the bacterial community structure are associated with the observed control of #IRhizoctonia#IR root rot, with NO production by soil bacteria potentially having a role in the induction of plant systemic resistance

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Photoinhibition of photosynthesis is reduced by water flow in the reef-building coral Acropora digitifera

Nakamura T, van Woesik R, Yamasaki H

MARINE ECOLOGY-PROGRESS SERIES ( その他の出版社 ) ( 301 ) 109 - 118 2005年03月 [ 査読有り ]

掲載種別: 研究論文（その他学術会議資料等）

While photosynthesis of symbiotic algae is essential for reef-building corals, excess irradiance inhibits photosynthesis through photoinhibition, which can lead to coral bleaching under elevated temperature conditions. Here we show that water flow reduces photoinhibition of in hospite endosymbionts in the coral #IAcropora digitifera#IR. Diurnal monitoring of chlorophyll fluorescence, under 2 different flow regimes (<3 and 20 cm s#U–1#UR flow rates) in an outdoor aquarium, showed reduced photoinhibition, but only under moderate flow conditions (20 cm s#U–1#UR). Experimental (laboratory) measurements, on time scales ranging from minutes to hours, showed that flow-mediated reductions in photoinhibition occurred not by enhancing recovery of the damaged photosystem, but rather through inducing differential photodamage. Moreover, experiments involving sequential light oscillations (500/20 and 1000/20 µmol photons m#U–2#UR s#U–1#UR) at 3 flow regimes, <3, 10, and 20 cm s#U–1#UR, on a time scale ranging from hours to days, revealed water-velocity-dependent reductions of dynamic photoinhibition. These results, on time scales ranging from minutes to weeks, confirm that reduced water flow amplifies photodamage of algal photosynthesis under strong irradiance, which in turn affects coral tolerance to strong irradiance and temperature.

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Inhibitory effects of flavonoids on alternative respiration of plant mitochondria

Shimoji H, Yamasaki H

BIOLOGIA PLANTARUM ( その他の出版社 ) 49 ( 1 ) 117 - 119 2005年03月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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The NO world for plants: achieving balance in an open system

Hideo Yamasaki

PLANT CELL AND ENVIRONMENT ( その他の出版社 ) 28 ( 1 ) 78 - 84 2005年01月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Nitric oxide (NO) is a free radical that had been known for many years simply as a toxic air pollutant. The discovery of enzymatic NO production in many living organisms has established a new paradigm: NO being an essential molecule endogenously produced in the cells. In plant science it has been suggested that NO acts as a plant hormone equivalent to ethylene; that is, as a gaseous signal transmitter. Even after experiencing such a scientific breakthrough, however, researchers may still feel difficulty in exploring plant NO signalling systems with conventional approaches. A major difference between plants and animals is that the growth and development of plants is closely linked to the surrounding environment where NO levels vary according to biotic and abiotic activities. This fundamental difference may make the NO‐signalling network system of plants larger and more complicated than that of vertebrates. This review intends to show prospects for the future of NO signalling research in plants by introducing a holistic concept to aid in the exploration of complicated systems such as the plant‐environment system. Furthermore, the novel ONS hypothesis is proposed to encompass the complexity and simplicity of NO in chemistry, biochemistry and physiology.

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Comment on 'Effects of geography, taxa, water flow, and temperature variation on coral bleaching intensity in Mauritius' (McClanahan et al. 2005)

van Woesik R, Nakamura T, Yamasaki H, Sheppard C

MARINE ECOLOGY-PROGRESS SERIES ( その他の出版社 ) ( 305 ) 297 - 299 2005年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Bioremediation of soils by plant-microbe systems

Michael F Cohen, Hideo Yamasaki, Mark Mozzola

INTERNATIONAL JOURNAL OF GREEN ENERGY ( その他の出版社 ) 1 ( 3 ) 301 - 312 2004年08月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Sustainable ecosystems can be designed to eliminate environmental toxins and reduce pathogen loads through the direct and indirect consequences of plant and microbial activities. We present an approach to the bioremediation of disturbed environments, focusing on petroleum hydrocarbon (PHC) contaminants. Treatment consists of incorporating a plant-based amendment to enhance ecosystem productivity and physiochemical degradation followed by the establishment of plants to serve as oxidizers and foundations for microbial communities. Promising amendments for widespread use are entire plants of the water fern Azolla and seed meal of Brassica napus (rapeseed). An inexpensive byproduct from the manufacture of biodiesel and lubricants, rapeseed meal is high in nitrogen (6% wt/wt), stimulates >100-fold increases in populations of resident Streptomyces species, and suppresses fungal infection of roots subsequently cultivated in the amended soil. Synergistic enzymatic and chemical activities of plant and microbial metabolism in root zones transform and degrade soil contaminants. Emphasis is given to mechanisms that enable PHC functionalization via reactive molecular species.

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Repair machinery of symbiotic photosynthesis as the primary target of heat stress for reef-building corals

Takahashi S, Sakamizu M, Nakamura T, van Woesik R, Yamasaki H

PLANT AND CELL PHYSIOLOGY ( その他の出版社 ) 45 ( 2 ) 251 - 255 2004年02月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

In a coral-algae symbiotic system, heat-dependent photoinhibition of photosystem II (PSII) leads to coral bleaching. When the reef-building coral #IAcropora digitifera#IR was exposed to light, a moderate increase of temperature induced coral bleaching through photobleaching of algal pigments, but not through expulsion of symbiotic algae. Monitoring of PSII photoinhibition revealed that heat-dependent photoinhibition was ascribed to inhibition of the repair of photodamaged PSII, and heat susceptibility of the repair machinery varied among coral species. We conclude that the efficiency of the photosynthesis repair machinery determines the bleaching susceptibility of coral species under elevated seawater temperatures.

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A photocarotenogenic Rhodococcus sp. isolated from the symbiotic fern Azolla

Cohen MF, Meziane T, Yamasaki H

Endocytobiosis and Cell Research 15 350 - 355 2004年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

An aerobic, heterotrophic bacterium, termed strain APG1, was isolated from surfacesterilized fronds of #IAzolla pinnata#IR, a water fern having symbiotic leaf cavities. Based on its fatty acid profile, morphology and biochemical characteristics, strain APG1 was assigned to the genus #IRhodococcus#IR. Exposure to light caused colonies to yellow due to accumulation of a ß-carotene-like pigment. We suggest that photocarotenogenesis and other traits of strain APG1 could facilitate the survival of the bacterium in planta.

Enzymatic nitration of phytophenolics: evidence for peroxynitrite-independent nitration of plant secondary metabolites

Sakihama Y, Tamaki R, Shimoji H, Ichiba T, Dukushi Y, Tahara S, Yamasaki H

FEBS LETTERS ( その他の出版社 ) 553 ( 3 ) 377 - 380 2003年10月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Peroxynitrite (ONOO#U−#UR), a reactive nitrogen species, is capable of nitrating tyrosine residue of proteins. Here we show in vitro evidence that plant phenolic compounds can also be nitrated by an ONOO#U−#UR‐independent mechanism. In the presence of NaNO#D2#DR, H#D2#DRO#D2#DR, and horseradish peroxidase (HRP), monophenolic #Ip#IR‐coumaric acid (#Ip#IR‐CA, 4‐hydroxycinnamic acid) was nitrated to form 4‐hydroxy‐3‐nitrocinnamic acid. The reaction was completely inhibited by KCN, an inhibitor for HRP. The antioxidant ascorbate suppressed #Ip#IR‐CA nitration and its suppression time depended strongly on ascorbate concentration. We conclude that nitrogen dioxide radical (NO#D2#DR#U #UR• ), but not ONOO#U−#UR, produced by a guaiacol peroxidase is the intermediate for phytophenolic nitration.

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Involvement of nitric oxide synthase in sucrose-enhanced hydrogen peroxide tolerance of Rhodococcus sp strain APG1, a plant-colonizing bacterium

Cohen MF, Yamasaki H

NITRIC OXIDE-BIOLOGY AND CHEMISTRY ( その他の出版社 ) 9 ( 1 ) 1 - 9 2003年08月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Hydrogen peroxide (H#D2#DRO#D2#DR) tolerance of #IRhodococcus#IR sp. strain APG1, previously isolated from the aquatic fern #IAzolla pinnata#IR, was examined in relation to nitric oxide (NO) production by cells cultured on a variety of C sources. Cells inoculated onto #IA. pinnata#IR fronds established a surface-sterilant resistant density of 2–4 × 107 cells g#U−1#UR without causing disease. Compared to cultures containing glucose, fructose, mannitol, or glycerol, those provided only with sucrose displayed, on a per C basis, substantially lower (<10%) growth yields and higher resistance to H#D2#DRO#D2#DR. NO, a positive regulator of catalase synthesis in bacteria, was produced in larger amounts in sucrose-grown cells as evidence by eightfold greater per cell accumulations in the medium of nitrite (NO#D2#DR#U−#UR), a stable oxidation product of NO. Addition to cells of L-arginine, the substrate for nitric oxide synthase (NOS), stimulated production of NO, detected both by fluorometric reaction with diaminofluorescein-FM diacetate (DAF-FM DA) and by increased levels of NO#D2#DR#U−#UR in the culture medium. These results suggest that sucrose may enhance H#D2#DRO#D2#DR tolerance of #IRhodococcus#IR APG1 by increasing cellular NO producing capacity. We propose a regulatory role for NOS in promoting tolerance of #IRhodococcus#IR APG1 to oxidative stress in the phyllosphere.

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Simultaneous time resolution of the emission spectra of fluorescent proteins and zooxanthellar chlorophyll in reef-building coral

Gilmore AM, Larkum AWD, Salih A, Itoh S, Shibata Y, Bena C, Yamasaki H, Papina M, Van Woesik R

PHOTOCHEMISTRY AND PHOTOBIOLOGY ( その他の出版社 ) 77 ( 5 ) 515 - 523 2003年05月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Light is absorbed by photosynthetic algal symbionts (i.e. zooxanthellae) and by chromophoric fluorescent proteins (FP) in reef-building coral tissue. We used a streak-camera spectrograph equipped with a pulsed, blue laser diode (50 ps, 405 nm) to simultaneously resolve the fluorescence spectra and kinetics for both the FP and the zooxanthellae. Shallow water (<9 m)–dwelling #IAcropora#IR spp. and #IPlesiastrea versipora#IR specimens were collected from Okinawa, Japan, and Sydney, Australia, respectively. The main FP emitted light in the blue, blue-green and green emission regions with each species exhibiting distinct color morphs and spectra. All corals showed rapidly decaying species and reciprocal rises in greener emission components indicating Förster resonance energy transfer (FRET) between FP populations. The energy transfer modes were around 250 ps, and the main decay modes of the acceptor FP were typically 1900–2800 ps. All zooxanthellae emitted similar spectra and kinetics with peak emission (∼683 nm) mainly from photosystem II (PSII) chlorophyll (chl)#I #IRa. Compared with the FP, the PSII emission exhibited similar rise times but much faster decay times, typically around 640–760 ps. The fluorescence kinetics and excitation versus emission mapping indicated that the FP emission played only a minor role, if any, in chl excitation. We thus suggest the FP could only indirectly act to absorb, screen and scatter light to protect PSII and underlying and surrounding animal tissue from excess visible and UV light. We conclude that our time-resolved spectral analysis and simulation revealed new FP emission components that would not be easily resolved at steady state because of their relatively rapid decays due to efficient FRET. We believe the methods show promise for future studies of coral bleaching and for potentially identifying FP species for use as genetic markers and FRET partners, like the related green FP from #IAequorea#IR spp.

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Water flow facilitates recovery from bleaching in the coral Stylophora pistillata

Nakamura T, Yamasaki H. van Woesik R

MARINE ECOLOGY-PROGRESS SERIES ( その他の出版社 ) ( 256 ) 287 - 291 2003年03月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Exposing partially bleached samples of #IStylophora pistillata#IR coral colonies to controlled water-flow treatments revealed differential recovery rates that varied in accordance with flow rate. Recovery of the number of zooxanthellae per unit area and chlorophyll #Ia#IR concentrations increased rapidly in moderate-flow treatments (of 20 cm s#U-1#UR), after an initial 3 wk of stasis. Colonies in low-flow treatments (≤3 cm s#U-1#UR) remained pale for the entire 7 wk experimental period and showed only slight increases in zooxanthellae per unit area. In an earlier study, we showed that when corals were subjected to high temperature and high irradiance, coral bleaching occurred in low-flow but not in moderate-flow treatments; the present study shows that recovery from bleaching is facilitated by flow treatment. In combination, prevention of and rapid recovery from bleaching by enhanced water flow suggest that the mechanisms that lead to dysfunction of the algae-coral symbiosis are driven by mass-transfer-limited processes.

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Involvement of nitric oxide in the mechanism for stomatal opening in Vicia faba leaves

Sakihama Y, Murakami S, Yamasaki H

Biologia Plantarum ( その他の出版社 ) 46 117 - 119 2003年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Feeding deterrence of the aquatic fern Azolla in relation to anthocyanin and fatty acid composition

Cohen MF, Mezine T, Tsuchiya M, Yamasaki H

Aquatic Botany ( その他の出版社 ) ( 74 ) 181 - 187 2002年10月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Higher levels of deoxyanthocyanins in #IAzolla#IR fronds correlated with feeding deterrence against adult #ILymnea swinhoei#IR snails and #IPolypedates leucomystax#IR tadpoles. After 7 days in co-culture, the growth yield of #IAzolla filiculoides#IR was almost twice that of #IAzolla pinnata#IR, which contained approximately 20-fold higher levels of deoxyanthocyanins. Inclusion of snails upon initiating a plant co-culture resulted in an A. pinnata growth yield that was 1.5-fold higher than that of #IA. filiculoides#IR. The two plant species did not differ significantly in fatty acid composition. However, snails incubated for 1 week solely with #IA. pinnata#IR showed a characteristic starvation-like fatty acid profile, with a two-fold lower proportion of polyunsaturated fatty acids (PUFAs) compared to snails that had access to #IA. filiculoides#IR, either as a sole food source or in co-culture with #IA. pinnata#IR. A 3-month cultivation of #IA. pinnata#IR with tadpoles resulted in fronds having a 260% higher concentration of deoxyanthocyanins and a 10-fold lower proportion of PUFAs in comparison to plants unexposed to tadpoles, indicating that prolonged feeding reduces the desirability of the surviving plants as a food source.

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Synergistic Effect of Deoxyanthocyanins from the Symbiotic Fern Azolla on hrmA Gene Induction in the Cyanobacterium Nostoc punctiforme.

Cohen MF, Sakihama Y, Takagi YC, Ichiba T, Yamasaki H

Molecular Plant Microbe Interactions ( その他の出版社 ) ( 15 ) 875 - 882 2002年09月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

The #IhrmA#IR gene of the N#D2#DR-fixing cyanobacterium #INostoc punctiforme#IR functions in repressing the formation of transitory motile filaments, termed hormogonia, by plant-associated vegetative filaments. Here, we report that anthocyanins can contribute to induction of #IhrmA#IR expression. Aqueous extract from fronds of the fern #IAzolla pinnata#IR, a host of symbiotic #INostoc#IR spp., was found to be a potent inducer of #IhrmA-luxAB#IR in #IN. punctiforme#IR strain UCD 328. The#I hrmA-luxAB#IR inducing activities of #IA. pinnat#IRa, as well as #IAzolla filiculoides#IR, were positively correlated with levels of frond deoxyanthocyanins. Analyses of the deoxyanthocyanins in frond extracts revealed, in order of predominance, an acetylated glycoside derivative of luteolinidin (m/z 475) and of apigeninidin (m/z 459) and minor amounts of a second luteolinidin derivative. At up to 150 μM, a purified preparation of deoxyanthocyanins only weakly induced #IhrmA-luxAB#IR on its own, but mixtures with #IhrmA-luxAB#IR inducers (#IA. filiculoides#IR extract or the flavonoid naringin) synergistically doubled to tripled their inducing activities. These results suggest that appropriately localized deoxyanthocyanins could function in plant-mediated mechanisms for repressing #INostoc#IR spp. hormogonium formation.

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