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論文(リポジトリ)

論文(リポジトリ)
水山, 克 ; Mizuyama, Masaru ; 久保, 弘文 ; Kubo, Hirofumi ; 藤田, 喜久 ; Fujita, Yoshihisa
出版情報: Fauna Ryukyuana — Fauna Ryukyuana.  64  pp.65-73,  2022-04-07.  琉球大学資料館 (風樹館)
概要: 琉球列島の海底洞窟 (沖縄諸島の沖縄島および伊江島, 宮古諸島の下地島) からハチノスキクザルChama cerion Matsukuma, Paulay & Hamada, 2003 の生貝を記録した. これらの標本は, 本種のホロタイプ 標本と同様に, 右殻表面に折れ曲がって重なり合う特徴的な鱗片状突起が確認され, また, この突起構造は左殻にも見られることが明らかとなった. 一方, 少なくとも本種のパラタイプ標本の一部には鱗片状突起が見らない個体が含まれており, C. cerion のパラタイプ標本にはホロタイプ標本とは異なる種 (おそらく未記載種) が含まれている可能性が示唆された. 本種の生貝記録は, トンガ王国ニウエ島で採集された一例のみとされてきたが, このパラタイプ標本はC. cerion ではない可能性があることから, 本報告が本種の確実な生貝の初記録となる. また, 本種が海底洞窟内のアンキアライン環境 (暗黒下かつ低塩分環境) に生息することも明らかとなった.
The rare chamid bivalve, Chama cerion Matsukuma, Paulay & Hamada, 2003, is recorded from submarine caves in Okinawa-jima Island and Ie-jima Island of the Okinawa Island Group, and Shimoji-jima Island of the Miyako Island Group, Ryukyu Islands, southwestern Japan. The specimens examined possessed bent over, overlapping scales that characterize the outer surface of right valve of the holotype of C. cerion, and these characteristic scales were also found in the left valve. On the other hand, these characteristic scales were not found in a paratype examined in this study. This indicates that at least one paratype is not conspecific to the holotype and they seem to consist of more than two species, including a potentially undescribed species. All the specimens of C. cerion from the Ryukyu Islands have been found in anchialine environments of submarine caves (darkness and low salinity conditions), and these records represent the first definite findings of living individuals of C. cerion.
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2.

論文(リポジトリ)

論文(リポジトリ)
藤田, 喜久 ; 水山, 克 ; Fujita, Yoshihisa ; Mizuyama, Masaru
出版情報: Fauna Ryukyuana.  33  pp.19-20,  琉球大学資料館 (風樹館) — Ryukyu University Museum, Fujukan
URL: http://hdl.handle.net/20.500.12000/38790
概要: A rare portunid crab, Atoportunus gustavi Ng & Takeda, 2003 (Decapoda: Brachyura: Portunidae), is recorded from submarin e caves in Okinawa-jima and Ie-jima Islands, Ryukyu Islands, southwestern Japan. This record represents the first discovery of A. gustavi from the islands and extends the geographical range of this species northward.
論文
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3.

論文(リポジトリ)

論文(リポジトリ)
Fujita, Yoshihisa ; Mizuyama, Masaru ; Yamada, Yusuke ; 藤田, 喜久 ; 水山, 克 ; 山田, 祐介
出版情報: Fauna Ryukyuana.  37  pp.31-33,  琉球大学資料館 (風樹館) — Ryukyu University Museum, Fujukan
URL: http://hdl.handle.net/20.500.12000/38813
概要: A rare bresiliid shrimp, Bresilia rufioculus Komai & Yamada, 2011, is recorded on the basis of a male specimen collected from a submarine cave in Shimoji-jima Island, Miyako Island Group, southern Ryukyus, Japan. This record represents the first finding of a male individual of B. rufioculus, and slightly extends the geographical range of this species southward.
論文
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4.

論文(リポジトリ)

論文(リポジトリ)
Sato, Yukuto ; Mizuyama, Masaru ; Sato, Megumi ; Minamoto, Toshifumi ; Kimura, Ryosuke ; Toma, Claudia
出版情報: Scientific Reports.  9  Springer Nature
URL: http://hdl.handle.net/20.500.12000/46981
概要: Leptospires, which cause the zoonotic disease leptospirosis, persist in soil and aqueous environments. Several factors, including rainfall, the presence of reservoir animals, and various abiotic and biotic components interact to influence leptospiral survival, persistence, and pathogenicity in the environment. However, how these factors modulate the risk of infection is poorly understood. Here we developed an approach using environmental DNA (eDNA) metabarcoding for detecting the microbiome, vertebrates, and pathogenic Leptospira in aquatic samples. Specifically, we combined 4 sets of primers to generate PCR products for high-throughput sequencing of multiple amplicons through next-generation sequencing. Using our method to analyze the eDNA of leptospirosis-endemic areas in northern Okinawa, Japan, we found that the microbiota in each river shifted over time. Operating taxonomic units corresponding to pathogenic L. alstonii, L. kmetyi, and L. interrogans were detected in association with 12 nonpathogenic bacterial species. In addition, the frequencies of 11 of these species correlated with the amount of rainfall. Furthermore, 10 vertebrate species, including Sus scrofa, Pteropus dasymallus, and Cynops ensicauda, showed high correlation with leptospiral eDNA detection. Our eDNA metabarcoding method is a powerful tool for understanding the environmental phase of Leptospira and predicting human infection risk.
論文
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5.

学位論文(リポジトリ)

学位
Mizuyama, Masaru ; 水山, 克
出版情報: University of the Ryukyus — 琉球大学
URL: http://hdl.handle.net/20.500.12000/47145
概要: 学位論文
6.

論文(リポジトリ)

論文(リポジトリ)
Toma, Claudia ; Murray, Gerald L. ; Nohara, Toshitsugu ; Mizuyama, Masaru ; Koizumi, Nobuo ; Adler, Ben ; Suzuki, Toshihiko
出版情報: Cellular Microbiology.  16  pp.1366-1377,  Wiley
URL: http://hdl.handle.net/20.500.12000/47485
概要: Leptospira interrogans is responsible for the zoonotic disease leptospirosis. The pathogenic mechanisms of this spirocha ete remain poorly understood; however, virulence has been correlated with increased phagocytic uptake and survival within macrophages. Leptospiral outer membrane proteins are thought to be responsible for persistence in vivo via interaction with specific host components. In this study, we analysed the transcriptional profile of a virulent strain and its culture‐attenuated derivative strain to identify bacterial factors that may be involved in pathogenesis. Two outer membrane proteins, LMB216 and LigB (leptospiral immunoglobulin‐like protein B) were downregulated more than 10‐fold in the culture‐attenuated strain. We show that both proteins play a role in leptospiral uptake by macrophages and that LMB216, as well as LigB, enhances the binding of leptospires to fibronectin. Taken together, our results indicate that LMB216 plays a role in pathogen interaction with host molecule/s, which may contribute to pathogenesis of leptospirosis.
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