論文 - 広瀬　裕一

Butterfly pupal wing tissue with an eyespot organizer

Joji M. Otaki, Atsuko Tanaka, Euichi Hirose

Cells & Development ( Elsevier BV )    203992 - 203992   2025年01月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Ascidian larvae discriminate nano-scale difference in surface structures during substrate selection for settlement

Daisuke Sakai, Noburu Sensui, Euichi Hirose

Zoological Science ( Zoological Society of Japan )  41 ( 6 ) 564 - 569   2024年11月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Regeneration of tunic cuticle is suppressed in edible ascidian Halocynthia roretzi contracting soft tunic syndrome

K Nakayama, Y Obayashi, L Munechika, SI Kitamura, T Yanagida, M Honjo, S Murakami, E Hirose

Diseases of Aquatic Organisms ( Inter-Research Science Center )  159   37 - 48   2024年08月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

Soft tunic syndrome is an infectious disease caused by the flagellate Azumiobodo hoyamushi, which severely damages the aquaculture of the edible ascidian Halocynthia roretzi. Tunic is a cellulosic extracellular matrix entirely covering the body in ascidians and other tunicates, and its dense cuticle layer covers the tunic surface as a physical barrier against microorganisms. When the tunic of intact H. roretzi individuals was cut into strips, electron-dense fibers (DFs) appeared on the cut surface of the tunic matrix and aggregated to regenerate a new cuticular layer in seawater within a few days. DF formation was partially or completely inhibited in individuals with soft tunic syndrome, and DF formation was also inhibited by the presence of some proteases, indicating the involvement of proteolysis in the process of tunic softening as well as cuticle regeneration. Using pure cultures of the causative flagellate A. hoyamushi, the expression of protease genes and secretion of some proteases were confirmed by RNA-seq analysis and a 4-methylcoumaryl-7-amide substrate assay. Some of these proteases may degrade proteins in the tunic matrix. These findings suggest that the proteases of A. hoyamushi is the key to understanding the mechanisms of cuticular regeneration inhibition and tunic softening.

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Optical properties of body mucus secreted from the coral reef sea slugs: Measurement of refractive indices and relative absorption spectra

Ryogo Takano, Euchi Hirose

Zoological Studies   23 ( 2 ) 1 - 10   2024年03月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Fine structures along the alimentary canal in a holoplanktonic gastropod, <i>Pterotrachea coronata</i>

Jun Nishikawa, Euichi Hirose

Plankton and Benthos Research ( The Plankton Society of Japan/The Japanese Association of Benthology )  18 ( 4 ) 198 - 205   2023年11月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Stack of cellular lamellae forms a silvered cortex to conceal the opaque organ in a transparent gastropod in epipelagic habitat

Daisuke Sakai, Jun Nishikawa, Hiroshi Kakiuchida, Euichi Hirose

PeerJ ( PeerJ )  10 ( e14284 ) e14284 - e14284   2022年10月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

Background Gelatinous zooplankton in epipelagic environments often have highly transparent bodies to avoid detection by their visual predators and prey; however, the digestive systems are often exceptionally opaque even in these organisms. In a holoplanktonic gastropod, Pterotrachea coronata, the visceral nucleus is an opaque organ located at the posterior end of its alimentary system, but this organ has a mirrored surface to conceal its internal opaque tissue. Results Our ultrastructural observation proved that the cortex of the visceral nucleus comprised a stack of thin cellular lamellae forming a Bragg reflector, and the thickness of lamellae (0.16 µm in average) and the spaces between the lamellae (0.1 µm in average) tended to become thinner toward inner lamellae. Based on the measured values, we built virtual models of the multilamellar layer comprising 50 lamellae and spaces, and the light reflection on the models was calculated using rigorous coupled wave analysis to evaluate their properties as reflectors. Our simulation supported the idea that the layer is a reflective tissue, and the thickness of the lamella/space must be chirped to reflect sunlight as white/silver light, mostly independent of the angle of incidence. Conclusions In P. coronata, the cortex of the visceral nucleus comprised multicellular lamellae that form a chirped Bragg reflector. It is distinct in structure from the intracellular Bragg structures of common iridophores. This novel Bragg reflector demonstrates the diversity and convergent evolution of reflective tissue using reflectin-like proteins in Mollusca.

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Innate immunity in the edible ascidian Halocynthia roretzi developing soft tunic syndrome: Hemolymph can eliminate the causative flagellates and discriminate allogeneic hemocytes

Tetsuya Yanagida, Kei Nakayama, Tomoo Sawada, Miho Honjo, Shoko Murakami, Takaji Iida, Euichi Hirose, Shin-Ichi Kitamura

Fish & Shellfish Immunology ( Elsevier BV )  127   659 - 665   2022年08月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

The infection of the kinetoplastid flagellate Azumiobodo hoyamushi causes soft tunic syndrome that often results in mass mortality in the aquaculture of the edible ascidian Halocynthia roretzi. In the diseased ascidian individuals, the flagellates are exclusively found in the tunic matrix that entirely cover the epidermis, and never invade into internal tissues, such as a mantle. The present study for the first time demonstrated that the ascidian blood plasma and hemolymph have an activity to agglutinate and disintegrate the flagellates, suggesting the innate immunity protects the internal tissue from the invasion of A. hoyamushi. This activity is indifferent between the healthy and the diseased individuals. Allo-specific recognition and cytotoxic reaction among ascidian hemocytes, so-called contact reaction, occur among the individuals of healthy–healthy, healthy–diseased, and diseased–diseased combination, and therefore, the hemocytes from diseased individuals still retain the allo-reactivity. Moreover, the allo-reactive combinations are not changed under the presence of the flagellates, indicating the flagellates neither suppress nor induce the effector system of the contact reaction. These results suggest that the infection of A. hoyamushi does not impair the innate immunity in the ascidian hemolymph.

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Prevalence, complete genome, and metabolic potentials of a phylogenetically novel cyanobacterial symbiont in the coral‐killing sponge, <i>Terpios hoshinota</i>

Yu‐Hsiang Chen, Hsing‐Ju Chen, Cheng‐Yu Yang, Jia‐Ho Shiu, Daphne Z. Hoh, Pei‐Wen Chiang, Wenhua Savanna Chow, Chaolun Allen Chen, Tin‐Han Shih, Szu‐Hsien Lin, Chi‐Ming Yang, James Davis Reimer, Euichi Hirose, Budhi Hascaryo Iskandar, Hui Huang, Peter J. Schupp, Chun Hong James Tan, Hideyuki Yamashiro, Ming‐Hui Liao, Sen‐Lin Tang

Environmental Microbiology ( Wiley )  24 ( 3 ) 1308 - 1325   2022年03月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Keeping a Clean Surface under Water: Nanoscale Nipple Array Decreases Surface Adsorption and Adhesion Forces

Kaoru Uesugi, Kazuaki Nagayama, Euichi Hirose

Journal of Marine Science and Engineering ( MDPI AG )  10 ( 1 ) 81 - 81   2022年01月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

While nanoscale nipple arrays are expected to reduce light reflection and/or dust contamination in some insects, similar structures have been reported in various marine invertebrates. To evaluate the anti-contamination property of the structure in aquatic regimes, we measured the adsorption and adhesion forces on the flat surface and MOSMITE™ (Mitsubishi Chemical Corporation, Tokyo, Japan), a synthetic material mimicking the nipple array, under water. A small force toward the surface occurred when the probe approached the substrate surface. This adsorption force was significantly smaller on MOSMITE™ than on the flat surface. The adhesion force toward the surface occurred when the probe was detached from the surface, and it was also significantly smaller on MOSMITE™ than on the flat surface. The adhesion force in the air was much greater than the force under water, and the force was also significantly smaller on MOSMITE™ than on the flat surface. In the aquatic regime, the nipple array provides less adsorption/adhesion properties for the surface and thus, the organisms would have less contamination of microparticles on their body surface. As the adsorption and adhesion forces are also involved in the attachment of cells, tissue, and larvae, less adhesive body surfaces should be beneficial for survival in aquatic environments, as well as land environments.

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Umbrella of <i>Mastigias papua</i> (Scyphozoa: Rhizostomeae: Mastigiidae): hardness and cytomorphology with remarks on colors

Yuki Hamaguchi, Akane Iida, Jun Nishikawa, Euichi Hirose

Plankton and Benthos Research ( The Plankton Society of Japan/The Japanese Association of Benthology )  16 ( 3 ) 221 - 227   2021年08月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Substrate selection of ascidian larva: Wettability and nano-structures

Hirose E, Sensui N

Journal of Marine Science and Engineering ( MDPI )  9   634   2021年06月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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How to Wear a Sandy Coat: Secretory Cells in the Dorsal Epidermis in the Sea Cucumber <i>Holothuria atra</i> (Echinodermata: Holothuroidea)

Nodoka Aruga, Euichi Hirose

Zoological Science ( Zoological Society of Japan )  38 ( 3 ) 252 - 258   2021年04月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Exumbrellar surface of jellyfish: a comparative fine structure study with remarks on surface reflectance

Hirose E, Sakai D, Iida A, Obayashi Y, Nishikawa J

Zoological Science   38 ( 2 ) 170 - 178   2021年04月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Reacquisition of light-harvesting genes in a marine cyanobacterium confers a broader solar niche

Nikea J. Ulrich, Hiroko Uchida, Yu Kanesaki, Euichi Hirose, Akio Murakami, Scott R. Miller

Current Biology ( Elsevier BV )  31 ( 7 ) 1539 - 1546   2021年02月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Seasonality and longevity of the functional chloroplasts retained by the sacoglossan sea slug Plakobranchus ocellatus van Hasselt, 1824 inhabiting a subtropical back reef off Okinawa-jima Island, Japan

Chihara S, Nakamura T, Hirose E

Zoological Studies   59   65   2020年12月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Convergent evolution of the vertical transmission mode of the cyanobacterial obligate symbiont Prochloron distributed in the tunic of colonial ascidians

Hirose E., Nozawa Yoko (担当範囲: corresponding author)

Journal of Zoological Systematics and Evolutionary Research ( Journal of Zoological Systematics and Evolutionary Research )  58   1058 - 1066   2020年11月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Biogeography and host-specificity of cyanobacterial symbionts in colonial ascidians of the genus Lissoclinum

Mirielle Lopez-Guzman, Patrick M. Erwin, Euichi Hirose, Susanna López-Legentil

Systematics and Biodiversity ( Informa UK Limited )  18 ( 5 ) 496 - 509   2020年07月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Latitudinal difference in the species richness of photosymbiotic ascidians along the east coast of Taiwan.

Hirose E, Nozawa Y

Zoological Studies ( Zoological Studies )  59 ( 19 ) 1 - 11   2020年06月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

Some didemnid ascidians harbor cyanobacterial symbionts, and this is the only obligate photosymbiosis system known in chordates. These photosymbiotic ascidians are found only in tropical and subtropical waters, probably because the photosymbionts are vulnerable to low temperatures. We surveyed the photosymbiotic ascidian fauna along the east coast of Taiwan. The present and previous reports recorded 13 species in Taiwan, and the species richness and composition is different in five areas along the east coast. Along the middle-east, southeast, and south coasts, five or more species have been recorded, whereas only one species has been found along the northeast coast, and no species have been recorded on the north coast. This gap in the species richness is probably related to the Kuroshio Current, which travels from south to north along the east coast of Taiwan but changes to an easterly direction off the northeast coast. Increases in water temperature due to global warming could cause northward expansion of the distribution ranges of these ascidians in the future. Hence, the photosymbiotic ascidian fauna could be an environmental indicator in subtropical, shallow water, and the present study provides a basic dataset that illustrates the current status of photosymbiotic ascidians in Taiwan.

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Wettability and Substrate Selection in the Larval Settlement of the Solitary Ascidian Phallusia philippinensis (Phlebobranchia: Ascidiidae)

Noburu Sensui, Euichi Hirose

Zoological Science ( Zoological Society of Japan )  37 ( 4 ) 366 - 366   2020年06月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Larvae of female Caecognathia sp. (Isopoda: Gnathiidae) are attracted to male adults and prolong their larval phase in the absence of males.

Hayashi, C, Tanaka, K, Hirose, E

Journal of Crustacean Biology ( OXFORD UNIV PRESS )  40 ( 2 ) 156 - 161   2020年03月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

The interaction between males and females (adults and/or larvae) of Caecognathia sp., a parasite of fishes, was studied in the laboratory to investigate the attraction of the opposite sexes and the induction of metamorphosis to adults. We reared the third-stage larvae collected by a light trap to develop them into adults. Their sex ratio was 104 males to 100 females, suggesting that females and males have similar fitness. The attraction experiments using an experimental chamber demonstrate that adult males attract female larvae that were also attracted by the dichloromethane extract of males but not the female extract. The males also induce the praniza females to develop into adults. When there are no males present, females can prolong the larval phase and moreover can spontaneously start to develop into adults after the prolonged larval phase. As in other isopods, the gnathiid female is supposed to be able to copulate immediately after metamorphosis, and the timing of metamorphosis is therefore crucial. The prolongable larval phase in the gnathiid female could be an adaptation to a polygynous, semelparous system and brief copulatory phase after the metamorphosis into adult female.

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