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SHIRAKASHI Sho
Aquaculture Research Institute, Kindai University | Associate Professor/Director |
■Researcher basic information
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- Parasite Ecology Fish Pathology Parasitology
■Career
Career
- 2016/04 - Today Kindai UniversityAquaculture Research InstituteAssociate Professor
- 2012/04 - 2016/03 Kindai UniversityAquaculture Research InstituteLecturer
- 2009/06 - 2012/03 Kindai UniversityAquaculture Research InstituteGCOE Research Fellow
- 2007/04 - 2009/05 Universty of MunichFaculity of Veterinary ScienceAlexander von Humboldt-Stifting Research Fellow
- 2006/07 - 2007/03 The University of Tokyo農学生命科学研究科農学特定研究員
- 2005/12 - 2006/05 University of BristolFaculty of Biological ScienceResearch Assistant
- 2005/04 - 2005/11 The University of Tokyo農学生命科学研究科技術補佐員
- 2003/04 - 2005/11 The University of Tokyo農学生命科学研究科日本学術振興会特別研究員
Educational Background
■Research activity information
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Paper
- Sho Shirakashi; Riko Kokaji; Mayuko MiuraAquaculture Elsevier BV 588 740954 - 740954 0044-8486 2024/07 [Refereed]
- Nguyen Ngoc Chinh; Vo Thi Ha; Tran Duc Dien; Mai Dang; Pham Ngoc Doanh; Christopher M Whipps; Sho ShirakashiThe Journal of parasitology 110 (4) 393 - 401 2024/07Myxospores discovered floating free in the bile of marine fishes from the south-central coast of Vietnam were identified using morphological and molecular methods, leading to the description of 2 new species. Ceratomyxa chauvanminhi n. sp. was detected in 16% (8/50) of cultured barramundi Lates calcarifer (Bloch) specimens, and Ceratomyxa sekoi n. sp. was found in 20% (5/25) of wild largehead hairtail Trichiurus lepturus Linnaeus specimens. The spores of C. chauvanminhi n. sp. are very shallowly ovoid, slightly crescent shaped, and 11.5 ± 0.5 (10.7-12.4) μm thick, 5.8 ± 0.2 (5.4-6.1) μm long, and 5.5 ± 0.2 (5.2-5.7) μm wide. Their posterior angles are slightly concave at 158.7° ± 4.2° (151.3°-164.8°), and they possess 2 equal spherical polar capsules 2.5 ± 0.2 (2.1-2.9) μm in diameter. The spores of C. sekoi n. sp. are 5.6 ± 0.2 (5.0-6.1) μm long, 75.5 ± 4.8 (68.9-90.0) μm thick, and 5.5 ± 0.1 (5.4-5.6) μm wide, with 2 equal, slightly anterior spherical polar capsules 2.1 ± 0.2 (1.7-2.4) μm in diameter. Although C. sekoi n. sp. spores resemble those of species of MyxodavisiaZhao, Zhou, Kent, and Whipps, 2008, characterized by long tapering valves, genetic analyses distinctly place this new species within the Ceratomyxa Thélohan, 1892 lineage. This study contributes to the understanding myxosporean diversity in Vietnamese waters and highlights the difficulty associated with distinguishing between the genera Ceratomyxa and Myxodavisia.
- Yuki Tomita; Keitaro Kato; Youhei Washio; Sho ShirakashiFish Pathology The Japanese Society of Fish Pathology 59 (2) 71 - 79 0388-788X 2024/06 [Refereed]
Aquaculture of the red seabream Pagrus major predominantly utilizes artificial seedlings of high-growth strains. Although effective broodstock management is crucial for sustainable production, internal parasitism in brood fish, particularly by the gonadal nematode Philometra madai, is often neglected. Despite its common occurrence in adult red seabream gonads, infection status of broodstocks and the effects on the brood fish health remain unexplored. This study conducted a 14-month survey on 3- to 4-year-old brood red seabream. Worm carcasses were consistently found in both male and female gonads throughout the year, with overall average prevalence of 86.4%. In some cases, these carcasses filled the entire gonad, including ovarian cavity and sperm ducts, extending to the area near the cloaca, potentially impeding ovulation and sperm release. However, no significant effects on gonadal development were observed and there was no correlation between worm weight and host weight, condition factor, or gonadosomatic index. Live P. madai were detected only during the red seabream spawning season, from March to May, with their maturation synchronized with host reproduction. This study represents the first survey of P. madai infections in high-growth strain red seabream broodstock. - Chinh Nguyen Ngoc; Sho ShirakashiAcademia Journal of Biology Publishing House for Science and Technology, Vietnam Academy of Science and Technology (Publications) 46 (1) 87 - 97 2615-9023 2024/03 [Refereed]
A brain-infecting myxozoan, Kudoa yasunagai (Hsieh & Chen, 1984), was identified using both morphological and molecular methods in a marine fish from Van Phong Bay, Khanh Hoa province, Vietnam. Cysts containing spores were observed in the brain of one out of 10 Siganus virgatus (Valenciennes) individuals (10%). The myxospores were radially symmetrical, containing a majority of 7 equal shell valves and polar capsules. The spores measured 6.6 ± 0.1 (6.4‒6.7) µm in length, 7.6 ± 0.5 (7.0‒8.4) µm in width, and 7.0 ± 0.4 (6.5‒7.7) µm in thickness. Polar capsules measured 2.8 ± 0.2 (2.6‒3.0) µm in length and 1.4 ± 0.1 (1.2‒1.5) µm in width, containing a filament inside. The SSU rDNA sequence from the Vietnamese specimen showed > 99.94 % identity with K. yasunagai from Japan and Australia. This report marks a new geographical and host record for K. yasunagai. - Kazuo Ogawa; Sho Shirakashi; Naoya Sata; Naoki Itoh; Shingo Ito; Eva Lewisch; Stephanie BornsteinSystematic Parasitology Springer Science and Business Media LLC 101 (2) 24 - 24 0165-5752 2024/03 [Refereed]
Discocotyle sagittata (Leuckart, 1842) (Monogenea: Discocotylidae) is redescribed, based on specimens collected from the type host, Salmo trutta Linnaeus, from the type locality, Freiburg, Germany, supplemented with specimens from S. trutta and rainbow trout, Oncorhynchus mykiss (Walbaum) reared in an Austrian aquarium. The diagnosis of the genus Discocotyle Diesing, 1850 is emended. Discocotyle ciray n. sp. is described, based on immature, preadult and adult specimens from the salmonid, Parahucho perryi (Brevoort) at Eniwa, Hokkaido, Japan. Adult specimens of the new species were about twice as large as those of D. sagittata from S. trutta. When the type specimens of D. ciray n. sp. were examined together with museum specimens from P. perryi at Tsurui, Hokkaido, the body and clamp sizes were positively correlated to the host size. Their measurements from a smaller P. perryi at Tsurui overlapped with those of D. sagittata, showing that these size differences were not suitable differentiating keys. Discocotyle ciray n. sp. can be separated from D. sagittata by the morphologies of the female genital system (relatively anteriorly positioned ovary, short joint vaginal duct and much more strongly winding uterus). The genetic distances of COI mtDNA sequence between D. ciray n. sp. and D. sagittata were 18.0-18.6%. These remarkable genetic divergences also supported the distinct taxonomic status of D. ciray n. sp. - Mai Sakakibara; Ryuichiro Aoki; Shukei Masuma; Osamu Nakamura; Sho Shirakashi; Shigeyuki TsutsuiDevelopmental & Comparative Immunology Elsevier BV 152 105113 - 105113 0145-305X 2023/12 [Refereed]
Interspecific hybrids of farm-raised fish are becoming popular in aquaculture owing to their advantages over pure species, including improved growth and higher resistance to infectious diseases. Kue-Tama is a recently established hybrid grouper derived from the longtooth grouper Epinephelus bruneus (♀) × giant grouper E. lanceolatus (♂). In our previous study, this hybrid showed significantly higher resistance against the skin fluke Benedenia epinepheli, a problematic parasite in grouper farming, than the longtooth grouper. In the present study, we explored lectins in the skin mucus of hybrids and their parent species. While C-type lectins of approximately 15 kDa were obtained from longtooth groupers, additional C-type lectins with molecular masses of approximately 20 and 30 kDa, as well as 45-kDa F-type lectin, were also detected in Kue-Tama and giant groupers. Semi-quantitative reverse transcript-polymerase chain reaction (RT-PCR) demonstrated that the gene expression levels of both C-type and F-type lectins were significantly higher in the skin of the hybrid and giant groupers than that of the longtooth grouper. In addition, some skin mucus lectins of the hybrid and giant groupers were bound to the fluke, suggesting that these lectins conferred resistance to parasitic infections. - Kazuo Ogawa; Masaaki Abe; Satoko Hara; Mutsuki Ueno; Sho ShirakashiFish Pathology The Japanese Society of Fish Pathology 58 (2) 71 - 73 0388-788X 2023/06 [Refereed]
- Nguyen Ngoc Chinh; Nguyen Thi Hoang Ha; Pham Ngoc Doanh; Jorge C. Eiras; Christopher M. Whipps; Sho ShirakashiSystematic Parasitology Springer Science and Business Media LLC 100 (4) 325 - 344 0165-5752 2023/04 [Refereed]
- Kazuo Ogawa; Naoya Sata; Yukitaka Sugihara; Haruki Miyazaki; Mutsuki Ueno; Sora Kuramochi; Sho ShirakashiFish Pathology The Japanese Society of Fish Pathology 58 (1) 15 - 21 0388-788X 2023/03 [Refereed]
- Kiyono Sekii; Soichiro Miyashita; Kentaro Yamaguchi; Ikuma Saito; Yuria Saito; Sayaka Manta; Masaki Ishikawa; Miyu Narita; Taro Watanabe; Riku Ito; Mizuki Taguchi; Ryohei Furukawa; Aoi Ikeuchi; Kayoko Matsuo; Goro Kurita; Takashi Kumagai; Sho Shirakashi; Kazuo Ogawa; Kimitoshi Sakamoto; Ryo Koyanagi; Noriyuki Satoh; Mizuki Sasaki; Takanobu Maezawa; Madoka Ichikawa-Seki; Kazuya KobayashiiScience Elsevier BV 26 (1) 105776 - 105776 2589-0042 2023/01 [Refereed]
- Tetsuya Yanagida; Nanami Asai; Michitaka Yamamoto; Kazuhiro Sugahara; Takuto Fujiwara; Sho Shirakashi; Hiroshi YokoyamaPARASITOLOGY CAMBRIDGE UNIV PRESS 150 (1) 1 - 14 0031-1820 2023/01 [Refereed]
A new microsporidian disease of cultured rainbow trout Oncorhynchus mykiss was recently confirmed in Japan, and the causative species was tentatively designated as Microsporidium sp. RBT-2021. Involvement of common prawn Palaemon paucidens in its transmission was suggested based on the previous feeding trials, although the microsporidian infection in P. paucidens was not confirmed. In this study, P. paucidens in Lake Biwa, Japan was investigated for microsporidian infection and four types of spores (Type 1-4) were newly found. The nucleotide sequence of the small subunit ribosomal RNA gene was identical between Type 1 and Microsporidium sp. RBT-2021, indicating they are conspecific. However, intriguingly, the spore morphology and the mode of development in fish and prawn were strikingly different. Morphological observations revealed Type 1 in the prawn possesses characteristics of the genus Inodosporus Overstreet and Weidner, 1974, while Microsporidium sp. RBT-2021 in the trout exhibited the characteristics of the genus Kabatana Lom, Dyková and Tonguthai, 2000. In the phylogeny, Type 1 was placed within a clade comprising Kabatana spp. and Inodosporus octosporus. Based on the morphological and molecular analyses, we describe Microsporidium sp. RBT-2021 as Inodosporus fujiokai n. sp. Together with the success of the previous prawn feeding trials, this study strongly suggests I. fujiokai n. sp. has a multi-host life cycle utilizing fish and crustacean hosts and different modes of development in each host. Such polymorphic life cycle has barely been known among fish microsporidians. This study also suggests that the genus Kabatana is a junior synonym of the genus Inodosporus. - Nguyen Ngoc Chinh; Nguyen Thi Tham; Violetta M Yurakhno; Pham Ngoc Doanh; Christopher M Whipps; Sho ShirakashiParasitology research SPRINGER 121 (9) 2495 - 2502 0932-0113 2022/09 [Refereed]
During a survey of myxosporean parasites of freshwater fishes in northern Vietnam, myxospores resembling those of the genus Myxobolus (Myxosporea: Myxobolidae) were found in the trunk muscle of 6 out of 35 specimens (17.14%) of wild goldfish Carassius auratus (Cypriniformes: Cyprinidae). The mature spores were 12.0 ± 0.4 (11.4 - 12.6) µm long, 8.5 ± 0.2 (7.9 - 9.0) µm wide and 6.1 ± 0.2 (5.8 - 6.3) µm thick, containing two pyriform-shaped polar capsules unequal in size. The larger polar capsule was 7.6 ± 0.3 (7.1 - 8.4) µm long and 3.5 ± 0.1 (3.3 - 3.8) µm wide, and the smaller polar capsule was 6.2 ± 0.3 (5.5 - 6.7) µm long and 2.9 ± 0.2 (2.6 - 3.4) µm wide. Each polar capsule contained a polar filament with 3-5 coils. A phylogenetic analysis based on the small subunit rDNA (SSU rDNA) sequence revealed that this Myxobolus species forms a distinct branch in the phylogenetic tree sister to Myxobolus artus and Myxobolus cyprini, with DNA sequence similarity at 97.6% to M. artus and 97.5% to M. cyprini. A combination of the morphological characteristics and molecular data suggest that this is an undescribed species, and we propose the name Myxobolus hoabinhensis n. sp. - Kazuo Ogawa; Sho Shirakashi; Yutaka FukudaFish Pathology The Japanese Society of Fish Pathology 57 (2) 49 - 55 0388-788X 2022/06 [Refereed]
- Luke J. Norbury; Sho Shirakashi; Cecilia Power; Barbara F. Nowak; Nathan J. BottInternational Journal for Parasitology: Drugs and Drug Resistance Elsevier BV 18 87 - 102 2211-3207 2022/04 [Refereed]
- Thomas H. Cribb; Rodney A. Bray; Jean-Lou Justine; James Reimer; Pierre Sasal; Sho Shirakashi; Scott C. CutmoreParasitology Cambridge University Press (CUP) 149 (6) 831 - 853 0031-1820 2022/03 [Refereed]
Abstract The taxonomy of species of Bivesicula Yamaguti, 1934 is analysed for samples from holocentrid, muraenid and serranid fishes from Japan, Ningaloo Reef (Western Australia), the Great Barrier Reef (Queensland), New Caledonia and French Polynesia. Analysis of three genetic markers (cox1 mtDNA, ITS2 and 28S rDNA) identifies three strongly supported clades of species and suggests that Bivesicula as presently recognized is not monophyletic. On the basis of combined morphological, molecular and biological data, 10 species are distinguished of which five are proposed as new. Bivesicula Clade 1 comprises seven species of which three are effectively morphologically cryptic relative to each other; all seven infect serranids and four also infect holocentrids. Bivesicula Clade 2 comprises three species of which two are effectively morphologically cryptic relative to each other; all three infect serranids and one also infects a muraenid. Bivesicula Clade 3 comprises two known species from apogonids and a pomacentrid, and forms a clade with species of Paucivitellosus Coil, Reid & Kuntz, 1965 to the exclusion of other Bivesicula species. Taxonomy in this genus is made challenging by the combination of low resolving power of ribosomal markers, the existence of regional cox1 mtDNA populations, exceptional and unpredictable host-specificity and geographical distribution, and significant host-induced morphological variation. - Nicholas Q-X. Wee; Thomas H. Cribb; Sho Shirakashi; Scott C. CutmoreParasitology Cambridge University Press (CUP) 1 - 18 0031-1820 2022/01 [Refereed]
Abstract We report specimens of monorchiids infecting Haemulidae from the waters off Japan and Australia; these specimens represent five species of Helicometroides Yamaguti, 1934, three of which are unambiguously new. Helicometroides murakamii n. sp. infects Diagramma pictum pictum from off Minabe, Japan; Helicometroides gabrieli n. sp. infects Plectorhinchus chrysotaenia from off Lizard Island, Australia; and Helicometroides wardae n. sp. infects Plectorhinchus flavomaculatus and Plectorhinchus multivittatus from off Heron Island, Australia. Helicometroides murakamii n. sp. and H. gabrieli n. sp. conform to the most recent diagnosis of Helicometroides in lacking a terminal organ, but H. wardae n. sp. possesses a terminal organ with distinct, robust spines; despite this morphological distinction, the three form a strongly-supported clade in phylogenetic analyses. We also report specimens morphologically consistent with Helicometroides longicollis Yamaguti, 1934, from D. pictum pictum from off Minabe, Japan, and Diagramma pictum labiosum on the Great Barrier Reef, Australia. Genetic analyses of ITS2 rDNA, 28S rDNA and cox1 mtDNA sequence data for the Japanese specimens reveal the presence of two distinct genotypes. Specimens of the two genotypes were discovered in mixed infections and are morphologically indistinguishable; neither genotype can be associated definitively with H. longicollis as originally described. We thus identify them as H. longicollis lineage 1 and 2, pending study of further fresh material. Genetic analyses of specimens from the Great Barrier Reef are consistent with the presence of only H. longicollis lineage 1. This species thus has a range that incorporates at least Australia and Japan, localities separated by over 7000 km. - Nguyen Ngoc Chinh; Nguyen Van Ha; Pham Ngoc Doanh; Yurakhno Violetta; Tomoyoshi Yoshinaga; Sho Shirakashi; Sascha L. Hallett; Christopher M. WhippsParasitology Research Springer Science and Business Media LLC 121 (2) 613 - 621 0932-0113 2022/01 [Refereed]
- Sho Shirakashi; Satoshi Nishikawa; Yuji Ishii; Hidemasa Kawakami; Yoshiaki Imaoka; Keisuke Yoshii; Jun Satoh; Chihaya Nakayasu; Mamoru Ishihara; Tomoko Fukui; Kazuhiko HiroseFish Pathology The Japanese Society of Fish Pathology 56 (4) 212 - 215 0388-788X 2021/12 [Refereed]
- S. C. Cutmore; R. Q. -Y. Yong; J. D. Reimer; S. Shirakashi; M. J. Nolan; T. H. CribbSYSTEMATIC PARASITOLOGY SPRINGER 98 (5-6) 641 - 664 0165-5752 2021/12 [Refereed]
Ankistromeces Nolan & Cribb, 2004 and Phthinomita Nolan & Cribb, 2006 are sister genera of threadlike blood flukes (Trematoda: Aporocotylidae) infecting teleost fishes of the tropical Indo-west Pacific. Here, we report new collections of these genera from Australia, Indonesia, and Japan. A new species of Ankistromeces, Ankistromeces kawamurain. sp., is described from Siganus spinus (Linnaeus) off Okinawa, Japan, and a new species of Phthinomita, Phthinomita abdita n. sp., from Choerodon cephalotes (Castelnau), in Moreton Bay, Australia; the new species are morphologically cryptic within their respective genera and are delineated by molecular and ecological data. Ankistromeces olsoni Nolan & Cribb, 2006 is reported from Siganus fuscescens (Houttuyn) off Heron Island (southern Great Barrier Reef), Lizard Island (northern Great Barrier Reef), and Okinawa and Wakayama Prefectures, Japan and from Siganus spinus (Linnaeus) from off Bali, Indonesia. Ankistromeces mariae Nolan & Cribb, 2004 is re-reported from the type-host, Meuschenia freycineti (Quoy & Gaimard), from a new location, Gypsy Bay, Tasmania. Phthinomita poulini Nolan & Cribb, 2006 is re-reported from its type-locality, Lizard Island, from a range of mullids, including five new host species, and its range is extended to include Moreton Bay. Phthinomita symplocos Nolan & Cribb, 2006 is reported from Bali and P. hallae Nolan & Cribb, 2006, P. jonesi Nolan & Cribb, 2006, P. littlewoodi Nolan & Cribb, 2006, and P. munozae Nolan & Cribb, 2006 are each re-reported from their type-host and type-localities. New cox1 mtDNA data were generated for all known species of these two genera from new and archival material. Analyses of these data enabled an evaluation of all known Phthinomita species; P. robertsthomsoni Nolan & Cribb, 2006 is synonymised with P. adlardi Nolan & Cribb, 2006, and P. brooksi Nolan & Cribb, 2006 is synonymised with P. sasali Nolan & Cribb, 2006. We highlight the failure of ITS2 data to delineate closely related aporocotylid species. In contrast, cox1 sequence data are proving reliable and effective in this context and we recommend their incorporation in future studies of blood fluke taxonomy. - Sho Shirakashi; Satoshi Nishikawa; Yuji Ishii; Hidemasa Kawakami; Jun Satoh; Chihaya Nakayasu; Mamoru Ishihara; Tomoko Fukui; Kazuhiko HiroseFISH PATHOLOGY JAPAN SOC FISH PATHOL DEPT FISHERIES-FAC AGR 56 (4) 205 - 211 0388-788X 2021/12 [Refereed]
Three experimental trials were conducted to determine the effective dose and administration period of a pro-benzimidazole anthelmintic drug febantel (FBT) against two gill monogenean species on amberjacks; Zeuxapta japonica on Seriola dumerili and Heteraxine heterocerca on Seriola quinqueradiata. The mean Z. japonica intensities were checked at 3 days after given FBT-coated feeds at the doses of 1, 5, 10, or 20 mg/kg body weight (BW)/day (d) for 5 consecutive days (trial 1), and 10 mg/kg BW/d for 1, 3, or 5 days (trial 2). Based on the results of these trials, the efficacy of oral FBT treatment was assessed for H. heterocerca infections at the treatment regime of 10 mg/kg BW/d for 3 or 5 days (trial 3). Over 95% FBT efficacies were achieved for both monogenean species when the fish received the dose of 10 mg/kg/d or higher for 5 consecutive days. Amberjacks showed no apparent avoidance to the FBT-coated feed and no apparent signs of the drug toxicity were detected. Our results demonstrated that the in -feed FBT treatment at the dose of 10 mg/kg BW/d for 5 days is an effective, easy, and practical control measure against gill monogenean infections in aquaculture of Seriola fish. - Michitaka Yamamoto; Sho Shirakashi; Nanami Asai; Tetsuya Yanagida; Kazuhiro Sugahara; Hiroshi YokoyamaFish Pathology The Japanese Society of Fish Pathology 56 (3) 130 - 139 0388-788X 2021/09 [Refereed]
- Hirotaka Mizuochi; Yutaro Fujiwara; Sho Shirakashi; Yuji Fujikura; Kazuo OgawaFish Pathology The Japanese Society of Fish Pathology 56 (3) 122 - 129 0388-788X 2021/09 [Refereed]
- S. C. Cutmore; R. Q.-Y. Yong; J. D. Reimer; S. Shirakashi; M. J. Nolan; T. H. CribbSystematic Parasitology Springer Science and Business Media LLC 98 (5-6) 641 - 664 0165-5752 2021/09 [Refereed]
- Sho Shirakashi; Nanami Asai; Mayuko MiuraParasitology Research Springer Science and Business Media LLC 120 (9) 3173 - 3180 0932-0113 2021/08 [Refereed]
- Sho Shirakashi; Nanami Asai; Jun Satoh; Chihaya NakayasuFish Pathology The Japanese Society of Fish Pathology 56 (2) 97 - 100 0388-788X 2021/06 [Refereed]
- Sho Shirakashi; Satoshi Miwa; Takuya Katsuki; Shogo Harakawa; Hidemasa Kawakami; Chihaya Nakayasu; Koh-ichiro MoriFish Pathology The Japanese Society of Fish Pathology 56 (2) 79 - 88 0388-788X 2021/06 [Refereed]
- Soetsu Yanagi; Jun Satoh; Tohru Mekata; Takamitsu Sakai; Hidemasa Kawakami; Shogo Harakawa; Sho Shirakashi; Shogo Hamano; Kei Fukudome; Kazuhiko Wada; Masatoshi Yamasaki; Toyohiro Nishioka; Chihaya Nakayasu; Koh-ichiro MoriFish Pathology The Japanese Society of Fish Pathology 56 (2) 62 - 70 0388-788X 2021/06 [Refereed]
- Kazuo Ogawa; Hirotaka Mizuochi; Tomofumi Yamaguchi; Sho Shirakashi; Nanami Asai; Yasuo AgawaFish Pathology The Japanese Society of Fish Pathology 55 (4) 117 - 124 0388-788X 2021/01 [Refereed]
- Nguyen Ngoc Chinh; Ha Duy Ngo; Vu Van Tuc; Naoki Itoh; Tomoyoshi Yoshinaga; Sho Shirakashi; Pham Ngoc DoanhParasitology Research Springer Science and Business Media LLC 120 (3) 877 - 885 0932-0113 2021/01 [Refereed]
- Sho Shirakashi; Sang Phil Shin; Tohru Mekata; Ikunari KiryuFish Pathology JAPAN SOC FISH PATHOL DEPT FISHERIES-FAC AGR 56 (3) 140 - 148 0388-788X 2021 [Refereed]
Kudoa septempunctata is an important myxozoan parasite in culture and capture fisheries as it causes food poisoning in humans. This species is generally considered a parasite of olive flounder Paralichthys olivaceus because K. septempunctata-related food poisoning cases are associated with consumption of raw infected P. olivaceus. However, the host range of K. septempunctata remains unclear. Moreover, there is scarce information on the lifecycle of the parasite, and this hinders the development of a fundamental prophylactic measure in fish farms. During the survey of wild fishes at a K. septempunctata endemic area, kudoid myxospores were detected in the somatic muscle of grass puffer Takifugu alboplumbeus and Japanese whiting, Sillago japonica. Our morphological, molecular, and histological analyses identified them as K. septempunctata. While the infection levels in T. alboplumbeus were higher (up to 92.3% prevalence) than those in S. japonica (23.8%), the maximum spore density in the muscle tissue was about 7×104/g in both fishes, which is far less than the food poisoning risk value of 1 × 106/g. These findings indicate a wide host range of K. septempunctata and further attention is required for its possible infections in fishes other than P. olivaceus. - Sho Shirakashi; Takuma TakagiAquaculture Research Hindawi Limited 52 (5) 1915 - 1924 1355-557X 2020/12 [Refereed]
- Daniel C. Huston; Kazuo Ogawa; Sho Shirakashi; Barbara F. NowakTrends in Parasitology Elsevier BV 36 (12) 1002 - 1012 1471-4922 2020/12 [Refereed]
- Sho Shirakashi; Tomoya Matsuda; Nanami Asai; Tomoki Honryo; Kazuo OgawaInternational Journal for Parasitology Elsevier BV 50 (10-11) 851 - 857 0020-7519 2020/09 [Refereed]
- Sho Shirakashi; Tsukasa Waki; Kazuo OgawaFish Pathology The Japanese Society of Fish Pathology 54 (4) 93 - 100 0388-788X 2020/01 [Refereed]
- Satoshi Kawato; Keigo Kobayashi; Sho Shirakashi; Soetsu Yanagi; Yutaka Fukuda; Hirofumi Yamashita; Reiko Nozaki; Ikuo Hirono; Hidehiro KondoFish Pathology The Japanese Society of Fish Pathology 54 (2) 27 - 33 0388-788X 2019/06 [Refereed]
- Keigo Kobayshi; Germaine Lau Gek Khin; Sho Shirakashi; Yusuke Mukai; Yukitaka Sugihara; Soetsu Yanagi; Ikuo Hirono; Hidehiro KondoFish Pathology The Japanese Society of Fish Pathology 53 (4) 124 - 127 0388-788X 2018/12 [Refereed]
- Hisashi Chuda; Kazuki Ieda; Sho Shirakashi; Shukei MasumaAQUACULTURE ELSEVIER SCIENCE BV 491 346 - 350 0044-8486 2018/04 [Refereed]
Interspecific hybrids of marine fish are becoming popular for aquaculture. The advantageous characteristics of hybrid fish include high growth rates, enhanced feed conversion rates, better appearance, high tolerance to environmental stress, and increased resistance to certain diseases. A new hybrid grouper Kue-Tama, female Epinephelus bruneus x male E. lanceolatus has recently been established. This hybrid showed significantly higher growth than that by E. bruneus and is considered a promising new species for aquaculture, especially in temperate areas where the slow growth of E. bruneus has prevented stable farming practices. The present study compared the resistance of Kue-Tama, its maternal parent E. bruneus and E. septemfasciatus, another popular grouper for farming, against the skin fluke, Benedenia epinepheli, which is a problematic parasite in grouper farming. The result of the cohabitation experimental infection showed that E. septemfasciatus was the most resistant to the skin fluke, followed by Kue-Tama and then E. bruneus. There appeared to be a negative relationship between the amount of mucus produced and the parasite intensity suggesting a resistance to skin flukes though the dry-weight of mucus collected from a given skin surface area did not differ between the three groupers. These results demonstrated that Kue-Tama has another favorable characteristic for aquaculture, in addition to their higher growth rate. - Kazuya Nagasawa; Sho ShirakashiCrustaceana Brill 91 (2) 251 - 255 0011-216X 2018
- Kazuya Nagasawa; Sho Shirakashi; Shinji YamamotoCRUSTACEANA BRILL ACADEMIC PUBLISHERS 91 (3) 375 - 377 0011-216X 2018 [Refereed]
- Michio Jinnai; Takao Kawai; Tetsuya Harada; Yasutaka Nishiyama; Hiroshi Yokoyama; Sho Shirakashi; Hiroshi Sato; Junko Sakata; Yuko Kumeda; Yutaka Fukuda; Kikuyo Ogata; Kentaro KawatsuINTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY ELSEVIER SCIENCE BV 259 59 - 67 0168-1605 2017/10 [Refereed]
Kudoa septempunctata, a myxosporean parasite of the olive flounder (Paralichthys olivaceus), causes foodbome gastroenteritis after ingestion of contaminated raw flounder. Available methods to detect K. septempunctata require expensive equipment, well-trained personnel, and lengthy procedures. Here we generated a novel monoclonal antibody (MAb 15G11) against K. septempunctata and used it to produce a prototype immunochromatographic assay (prototype Kudoa-ICA). Within 15 min, the prototype Kudoa-ICA detected >= 1.0 x 10(5) spores/mL in a spore suspension and >= 2.0 x 10(4) spores/g of P. olivaceus muscle. The prototype Kudoa-ICA weakly cross-reacted with spores of K. lateolabracis and K. iwatai. cDNA sequence, expression, and western blot analyses revealed that MAb 15G11 detected an approximately 24-kDa protein encoded by a 573 bp mRNA. The cDNA nucleotide and predicted amino acid sequences were not significantly similar to any sequence in the GeneBank database. Immunoelectron microscopy revealed that MAb 15G11 reacted with the sporoplasmic cells and mainly with the capsulogenic cells of the K. septempunctata spore. Although the Kudoa-ICA was weakly cross-reactive with two other Kudoa species, it detected > 1.0 x 10(6) spores/g of K. septempunctata in P. olivaceus muscle, which is the criterion used to indicate a violation of the Food Hygiene Law of Japan. We conclude that MAb 15G11 may be suitable for use in an immunochromatographic assay for screening P. olivaceus muscle contaminated with K. septempunctata at food distribution sites such as food wholesalers, grocery stores, and restaurants. - Sho Shirakashi; Kazuki Tani; Katsuya Ishimuru; Tomoki Honryo; Sang Phil Shin; Hiro'omi Uchida; Kazuo OgawaJOURNAL OF PARASITOLOGY AMER SOC PARASITOLOGISTS 103 (5) 541 - 546 0022-3395 2017/10 [Refereed]
Fish blood flukes of the genus Cardicola (Digenea: Aporocotylidae) are important pathogens in tuna aquaculture. Recent advances in marine blood fluke research have led to the elucidation of the lifecycles of 3 Cardicola spp. infecting tuna; all 3 flukes utilize terebellid polychaetes as the intermediate host. In our survey, we obtained large numbers of Nicolea gracilibranchis infected by larval Cardicola orientalis at our tuna farming site. To determine the spatial and temporal changes in the distribution of N. gracilibranchis surrounding tuna culture cages and their infection by C. orientalis, we conducted monthly sampling for a period of 1 yr. Terebellids were most abundant on the floats and ropes of culture cages, but a significantly higher proportion of infected N. gracilibranchis was detected on ropes, particularly up to 4 m in depth. Cardicola orientalis infection in N. gracilibranchis was clearly seasonal, with a higher infection rate between April and July. Our findings indicate that the infected terebellids inhabit specific microhabitats, and both abiotic and biotic factors likely influence blood fluke infection in the intermediate terebellid host. This information is important to better understand the general biology of marine aporocotylids and may be useful to develop a control strategy for blood fluke infection in tuna aquaculture. - S. P. Shin; S. ShirakashiJOURNAL OF FISH DISEASES WILEY 40 (2) 287 - 291 0140-7775 2017/02 [Refereed]
- Kazuo Ogawa; Sho Shirakashi; Kazuki Tani; Sang Phil Shin; Katsuya Ishimaru; Tomoki Honryo; Yukitaka Sugihara; Hiro'omi UchidaPARASITOLOGY INTERNATIONAL ELSEVIER IRELAND LTD 66 (1) 972 - 977 1383-5769 2017/02 [Refereed]
Farming of Pacific bluefin tuna (PBT), Thunnus orientalis, is a rapidly growing industry in Japan. Aporocotylid blood flukes of the genus Cardicola comprising C orientalis, C. opisthorchis and C. forsteri are parasites of economic importance for PBT farming. Recently, terebellid polychaetes have been identified as the intermediate hosts for all these parasites. We collected infected polychaetes, Terebella sp., the intermediate host of C. opisthorchis, from ropes and floats attached to tuna cages in Tsushima, Nagasaki Prefecture, Japan. Also, Neoamphitrite vigintipes (formerly as Amphitrite sp. sensu Shirakashi et al., 2016), the intermediate host of C. forsteri, were collected from culture cages in Kushimoto, Wakayama Prefecture, Japan. The terebellid intermediate hosts harbored the sporocysts and cercariae in their body cavity. Developmental stages of these blood flukes were molecularly identified using species specific PCR primers. In this paper, we describe the cercaria and sporocyst stages of C. opisthorchis and C. forsteri and compare their morphological characteristics among three Cardicola blood flukes infecting PBT. We also discuss phylogenetic relations of the six genera of the terebellid intermediate hosts (Artacama, Lanassa, Longicarpus, Terebella, Nicolea and Neoamphitrite) of blood flukes infecting marine fishes, based on their morphological characters. (C) 2016 Elsevier Ireland Ltd. All rights reserved. - Nagasawa Kazuya; Shirakashi ShoCrustacean Research Carcinological Society of Japan 46 95 - 101 0287-3478 2017
Ovigerous females of Nerocila phaiopleura Bleeker, 1857 were collected from the body surface of young Pacific bluefin tuna, Thunnus orientalis (Temminck & Schlegel, 1844), cultured in Japan. This represents the first record of N. phaiopleura in finfish mariculture. The species is the third cymothoid isopod from maricultured fishes in Japan. The infected fish had a large hemorrhagic wound caused by N. phaiopleura at the attachment site. Thunnus orientalis is a new host of the isopod. No cymothoid infection has so far been reported from wild individuals of T. orientalis that swims at high speeds in the oceans, and the observed occurrence of N. phaiopleura on this fish species is regarded as unusual under confined mariculture conditions. The hosts and geographical distribution records of N. phaiopleura in Japan are reviewed.
- Ylenia Pennacchi; Sho Shirakashi; Barbara F. Nowak; Andrew R. BridleFISH & SHELLFISH IMMUNOLOGY ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD 58 490 - 499 1050-4648 2016/11 [Refereed]
Pacific bluefin tuna (PBT), Thunnus orientalis, due to its high average price on the market is an economically valuable fish species. Infections by blood flukes from the genus Cardicola (Trematoda: Aporocotylidae) represent a growing concern for the cage culture of bluefin tuna in Japan, Australia and Southern Europe. The accumulation of numerous Cardicola eggs in the fish gills causes severe pathology that has been linked to mortality in PBT juveniles up to one year old. The only effective treatment used to mitigate the infection is the oral administration of the antihelminthic drug praziquantel (PZQ) to the affected fish. However, with the need to minimise therapeutic drug use in aquaculture it is hoped that immunoprophylaxis can provide a future alternative to protect the PBT juveniles against Cardicola infection. Currently, little is known of the host immune response to these parasites and of their infection dynamics. In this study, using real-time qPCR we aimed to quantitatively detect C orientalis and C. opisthorchis DNA within the gills and heart of cultured PBT juveniles and to investigate the host immune response at the transcriptional level in the gills. The research focused mainly during early stages of infection soon after young PBT were transferred to culture cages (from 14 to 77 days post-transfer). An increase (up to 11-fold) of immune-related genes, namely IgM, MHC-I, TCR-beta and IL-1 beta was observed in the PBT gills infected with Cardicola spp. (28-77 days post-transfer). Furthermore, IgM (19 -fold increase) and MHC-I (11.5-fold increase) transcription was strongly up-regulated in gill samples of PBT infected with C orientalis relative to uninfected fish but not in fish infected with C opisthorchis. Cardicola-specific DNA was first detected in the host 14 days post-transfer (DPT) to sea-cages which was 55 days earlier than the first detection of parasite eggs and adults by microscopy. Oral administration of PZQ did not have an immediate effect on parasite DNA presence in the host and the DNA presence started to reduce after 24 days only in the host heart. The results provide evidence of an immune response in early age sea cage cultured juveniles of PBT naturally infected with C. orientalis and C opisthorchis. This response, whilst not protective against primary infection, provides evidence that immunisation at an early age may have potential as a health strategy. (C) 2016 Elsevier Ltd. All rights reserved. - Sang Phil Shin; Hiroe Ishitani; Sho ShirakashiAQUACULTURE ELSEVIER 464 37 - 41 0044-8486 2016/11 [Refereed]
Since the identification of Kudoa septempunctata as a causative agent of human food poisoning, Kudoa infections have becomea serious concern in the aquaculture of olive flounder (Paralichthys olivaceus). In order to ensure the safety of cultured flounder, various methods have been developed to detect K. septempunctata. However, less attention has been paid for inspection and detection of other Kudoa species. To date, six Kudoa spp. have been reported from olive flounder, 3 species each fromthe trunkmuscle, 2 species fromthe brain, and one species from the heart. During our routine inspection of cultured olive flounder, we isolated several Kudoa species including Kudoa igami and Kudoa ogawai in addition to the list of previously reported species. In the present study, a multiplex PCR (mPCR) was developed to detect all Kudoa spp. known to date fromolive flounder in Japan. ThemPCR also differentiate K. septempunctata among other Kudoa spp. simultaneously. The developed mPCR successfully detected seven Kudoa spp. and differentiated K. septempunctata with a sensitivity of 103 myxospores. Thus, mPCR offers a reliable and relatively simple method to detect Kudoa infection in olive flounder, specifically aiming to identify K. septempunctata infection.Statement of Relevance: Olive flounder Paralichthys olivaceus is one of themost important fish species for commercial aquaculture and fishery trading in Japan and Korea. Infections of microscopic myxozoan parasite of genus Kudoa (Myxozoa: Multivalvulida) has become a serious concern in flounder culture since the recent identification of Kudoa septempunctata as a causative agent of human food poisoning. Although various detection methods have been developed for the inspection of K. septempunctata, relatively little attentions are given to other Kudoa spp. We added K. ogawai and K. igami to the list of Kudoa spp. infecting olive flounder and developed multiplex PCR to simultaneously detect Kudoa spp. and distinguish K. septempunctata. This offers relatively simple and method to inspect Kudoa spp. in cultured flounder. (C) 2016 Elsevier B.V. All rights reserved. - Yasuo Agawa; Kazuki Tani; Syuhei Yamamoto; Chihaya Hirano; Sho ShirakashiFISHERIES SCIENCE SPRINGER JAPAN KK 82 (5) 827 - 833 0919-9268 2016/09 [Refereed]
Skin fluke Neobenedenia girellae infection is a chronic problem in marine finfish aquaculture. Current control measures rely on bath treatments, which are labor intensive and cause significant stress to fish. Although there is an urgent need to develop a strategy to prevent this infection, little is known about the distribution of the larval stage of the skin fluke around culture cages. We aimed to develop a Neobenedenia-specific real-time quantitative polymerase chain reaction (qPCR) assay to detect and quantify N. girellae larvae in environmental water. New PCR primers targeting mitochondrial DNA were designed and showed specificity for N. girellae among five capsalid monogeneans known to occur in Japanese waters. A single N. girellae oncomiracidium is estimated to carry 2.2 million copies of mitochondrial DNA, and the qPCR assay reliably detects DNA equivalent to half of that. We used this qPCR to quantify N. girellae larvae from a fish culture site. Analyses of water samples collected inside shaded culture cages of Seriola dumerili revealed lower larval density than that in the unshaded cage. The results indicate the usefulness of this newly developed qPCR assay for monitoring skin fluke larval density and distribution in fish farms. - Sang Phil Shin; Sho Shirakashi; Shogo Hamano; Keitaro Kato; Lissette Trejos Lasso; Hiroshi YokoyamaMOLECULAR PHYLOGENETICS AND EVOLUTION ACADEMIC PRESS INC ELSEVIER SCIENCE 98 337 - 345 1055-7903 2016/05 [Refereed]
Kudoa rayformis n. sp. (Myxozoa; Multivalvulida) was observed in the trunk muscle of Pacific sierra Scomberomorus sierra caught off the coast of Tonosi, Panama. The species formed pseudocysts in myofibers and infection was subclinical. The myxospores possessed four polar capsules and spore valves, one of which had a distinct filamentous extension. This unique morphological characteristic of the myxospore validated this as a new species of Kudoa. Genetically, K. rayformis n. sp. is closest to K. inornata, with 98% and 91% similarity in 18S and 28S rDNA, respectively, but its spore shape was clearly distinct. The 18S rDNA and concatenated sequences from K. rayformis were used in molecular phylogenetic analyses of kudoids to examine the congruence of phylogeny with infection site tropism, spore morphology and cyst/pseudocyst formation. The results demonstrated that the phenotypic traits were correlated with the phylogeny of Kudoidae, and that the biological features of K. rayformis originated from the ancient Kudoidae as exhibited by the non-specific infection site tropism and the ability to infect muscle and form pseudocysts. (C) 2016 Elsevier Inc. All rights reserved. - Sho Shirakashi; Kazuki Tani; Katsuya Ishimaru; Sang Phil Shin; Tomoki Honryo; Hiro'omi Uchida; Kazuo OgawaPARASITOLOGY INTERNATIONAL ELSEVIER IRELAND LTD 65 (2) 128 - 136 1383-5769 2016/04 [Refereed]
Fish blood flukes (Aporocotylidae) are important pathogens of farmed finfish around the world. Among them, Cardicola spp. infecting farmed tuna are considered to be serious threats to tuna farming and have received tremendous attention. We conducted periodical samplings at a tuna farming site in Japan between January and May, 2015 to determine the life cycle of Cardicola spp. We collected over 4700 terebellid polychaetes from ropes, floats and frames of tuna culture cages and found nearly 400 infected worms. Sporocysts and cercariae found in Nicolea gracilibranchis were genetically identified as Cardicola orientalis by 28S and ITS2 ribosomal DNA sequences. This was the first discovery of the intermediate host for this parasite species. Infection prevalence and the abundance of N. gracilibranchis significantly varied between sampling points and the highest number of infected terebellids were collected from ropes. We also demonstrated morphologically and molecularly that asexual stages found in a single Amphitrite sp. (Terebellidae) and adult worms isolated from farmed juvenile tuna were Cardicola forsteri. This is the first report of C forsteri in Pacific bluefin tuna (PBT) Thunnus orientalis in Japan. Our results demonstrated that all three species of Cardicola orientalis, C. forsteri and Cardicola opisthorchis exist in Japanese farmed PBTs and that they all use terebellid polychaetes as the intermediate hosts. (C) 2015 Elsevier Ireland Ltd. All rights reserved. - Jimena Balli; Ivona Mladineo; Sho Shirakashi; Barbara F. NowakAdvances in Tuna Aquaculture Elsevier 253 - 272 2016
- Sang Phil Shin; Tomoyo Nishimura; Kazuo Ogawa; Sho ShirakashiFish Pathology The Japanese Society of Fish Pathology 51 (3) 128 - 131 0388-788X 2016 [Refereed]
- Sho Shirakashi; Chihaya HiranoAQUACULTURE ELSEVIER SCIENCE BV 443 1 - 4 0044-8486 2015/06 [Refereed]
Skin fluke causes chronic problems in marine finfish aquaculture. Their eggs possess a long filamentous appendage that allows them to easily attach to culture cages. Fish farmers periodically change and clean cage nets to remove eggs from the culture sites. However, there is very little information about the accumulation rate and distribution of skin fluke eggs on culture cages. We conducted an experiment at a culture site to assess the accumulation of eggs of the Neobenedenia girellae skin fluke at different culture cage depths. In all three trials, we observed the highest egg accumulation in shallow areas, and the egg number decreased with the depth; however, the second highest accumulation was observed at the deepest depth. These distribution patterns likely reflect the behavior of fish within the cage. The highest accumulation rate was 161.2 eggs/cm(2)/day, with an estimated daily accumulation of more than 10 million eggs on the entire cage ( excluding the cage floor). Such information is useful for optimizing and managing cage net changing and also for the development of a new method of removing/killing parasite eggs. (C) 2015 Elsevier B.V. All rights reserved. - Chihaya Hirano; Katsuya Ishimaru; Sho ShirakashiFish Pathology The Japanese Society of Fish Pathology 50 (1) 23 - 28 0388-788X 2015Diurnal rhythms in egg laying and hatching of the skin fluke Neobenedenia girellae were investigated under different light conditions. Egg production was monitored every 2 h for 3 days under two light conditions (darkness and natural light) using Seriola dumerili infected with multiple Neobenedenia girellae as well as black molly Poecilia sphenops that had been transplanted by a single mature fluke. In any cases, oviposition was continuously observed with no obvious diurnal rhythm. The maximum egg production was approximately 60 eggs/h/worm for both multiple- and single-infection. Such high fecundity emphasizes the importance of the prompt eradication of mature flukes from culture sites to prevent parasite multiplication. The hatching rhythm was monitored under natural light condition and controlled light condition with LED lamp (24L, 12L:12D, 24D). An obvious hatching rhythm with a monomodal peak in the morning was detected under natural light condition. This rhythm was different from that previously reported for Benedenia seriolae whose hatching has bimodal peaks in the early morning and evening. Under controlled light conditions, no such pattern was observed and the overall hatching was considerably less than that under natural light condition.
- Shinji Yamamoto; Atsuhiko Fukushima; Katsuya Ishimaru; Sho ShirakashiFISHERIES SCIENCE SPRINGER JAPAN KK 80 (5) 1021 - 1026 0919-9268 2014/09 [Refereed]
The skin fluke Neobenedenia girellae has become a serious problem in Japan since the 1990s. Present control methods focus on the removal of the attached parasite and these post-infection treatments are often labor intensive, time consuming, and/or stressful to fish. Chub mackerel Scomber japonicus are highly susceptible to N. girellae. However, because of their sensitive nature, bath treatments may cause mortality. In this study, we investigated the efficacy of cage shading to reduce skin fluke infection and the frequency of conventional post-infection treatments. Juvenile mackerel were reared in cages with or without shade for 3 months and their skin fluke infections were monitored. We performed either freshwater baths or oral administration of praziquantel if fluke intensity exceeded the given criteria. In unshaded cages, 3 total bath treatments or 6 total drug treatments were conducted. In contrast, no treatment was required for the shaded cage. The overall fluke intensity in the shaded cage was less than half that of the unshaded cages, despite the lack of treatments. This study demonstrated for the first time the practical use of shading in fish farms to reduce skin fluke infection. - Hiroshi Yokoyama; Jun Suzuki; Sho ShirakashiPARASITOLOGY INTERNATIONAL ELSEVIER IRELAND LTD 63 (4) 571 - 579 1383-5769 2014/08 [Refereed]
Since Kudoa septempunctata in olive flounder (Paralichthys olivaceus) was indicated to cause food poisoning in humans, other Kudoa species are suspected to have pathogenic potential. Recently, a myxosporean possibly associated with food poisoning in humans consuming raw Pacific bluefin tuna, Thunnus orientalis, was identified as Kudoa neothunni. This is a known causative myxosporean of post-harvest myoliquefaction in yellowfin tuna Thunnus albacares. Regardless of the significant differences in the 28S rDNA sequence and the pathological character (with/without myoliquefaction) between the two T. orientalis and T. albacares isolates, they were considered intraspecific variants of K. neothunni. However, the light and low-vacuum electron microscopic observations in the present study revealed that there were two morphotypes; pointed- and round-type spores, which were significantly differentiated by the ratio of suture width to spore width. Furthermore, the two morphotypes were genetically distinguishable by the 28S rDNA sequence analysis. This morphological and molecular evidence validates that the two Kudoa types are separate species, and thus the pointed- and round-types are referred to as K. neothunni and Kudoa hexapunctata n. sp., respectively. K. neothunni was detected solely from T. albacares, whereas K. hexapunctata n. sp. was found not only from T. orientalis but also from T. albacares. (C) 2014 Elsevier Ireland Ltd. All rights reserved. - Sho Shirakashi; Koji Yamane; Hiroe Ishitani; Tetsuya Yanagida; Hiroshi YokoyamaPARASITOLOGY RESEARCH SPRINGER 113 (7) 2515 - 2524 0932-0113 2014/07 [Refereed]
Three species of the Kudoid parasite (Myxozoa: Multivalvulida) were observed in the somatic muscle of Japanese parrotfish Calotomus japonicus caught off the coast of western Japan. All three species formed pseudocysts in myofibers and caused subclinical infections. The three Kudoa species were distinguished by spore morphology, as well as their 18S and 28S rDNA sequences. We identified a previously undescribed taxa Kudoa igami n. sp. with spores that were stellate with rounded peripheral edges and five to six polar capsules (prevalence 29.3 %). Kudoa igami n. sp. were morphologically most similar to Kudoa neothunni but were distinguishable by a more rounded shape in the apical view. Molecular analyses demonstrated that the K. igami n. sp. is closely related to Kudoa thalassomi; however, the similarity in the 28S rDNA sequence was <96 % and the spore morphology was different. We found Kudoa thalassomi in one sample (prevalence 2.4 %), which is a new host and geographical record for this species. Kudoa lateolabracis, which causes postmortem myoliquefaction in Chinese sea bass Lateolabrax sp. and olive flounder Paralichthys olivaceus was found in Japanese parrotfish (prevalence 41.5 %) for the first time, but did not cause myoliquefaction. We also expanded the host record for the brain-infecting Kudoa yasunagai (prevalence 94.1 %). In addition, an unidentified microsporidia was observed in the somatic muscle (prevalence 23.3 %). - K. Ogawa; S. Shirakashi; H. IshitaniPARASITOLOGY INTERNATIONAL ELSEVIER IRELAND LTD 63 (2) 473 - 478 1383-5769 2014/04 [Refereed]
In vitro spermatophore formation and insemination of Neobenedenia girellae (Monogenea: Capsalidae, Benedeniinae) were recorded on video and described for the first time. Upon contact of two individuals, the anterior adhesive discs of the donor firmly attached to the dorsal tegument of the recipient and the donor's fore body strongly contracted such that the genital pore region protruded and the penis was pushed anteriorly to protrude through the genital pore. It is hypothesised that the donor penis mechanically damaged the tegument of the recipient. The sperm and spermatophore matrix were released together through the penis, which was placed under the left anterior attachment disc immediately behind the adhesive pad. The spermatophore matrix containing the spermatozoa became solid and attached to the dorsal surface of recipient's body. When observed under scanning electron microscopy, the spermatophores were irregularly shaped, with a diameter of 52-83 mu m. Under light microscopy they consisted of a proximal eosinophilic matrix portion and a distal thin-walled portion containing spermatozoa. Both parts were enclosed with a thin outer casing. Insemination occurred during and after spermatophore formation. Three types of insemination were recorded, unilateral and mutual insemination and self-insemination. The presence of self-insemination indicates that even a single N. girellae on a cultured fish may cause a significant parasite infection in the entire aquaculture system. (C) 2013 Elsevier Ireland Ltd. All rights reserved. - Katsuya Ishimaru; Takumi Matsuura; Kazunobu Tsunemoto; Sho ShirakashiDISEASES OF AQUATIC ORGANISMS INTER-RESEARCH 108 (1) 45 - 52 0177-5103 2014/02 [Refereed]
Kudoid myxozoans pose serious chronic problems in marine fisheries by causing pathological damage to host fish, reducing the market value of infected fish and potentially threatening public health. Kudoa yasunagai is a cosmopolitan parasite that infects the brains of various marine fishes, including important aquaculture species. We developed a quantitative PCR assay to detect K. yasunagai in sea water, and we used it to monitor abundance of the parasite in the environment and in culture through spring and winter. Quantitative PCR detected K. yasunagai DNA from sea water, with the lowest reliable threshold of 162 copies 28S rDNA l(-1). Parasite DNA was detected sporadically in sea water throughout the study period of May through December 2012. The highest level of detected DNA occurred in mid-December (winter), at 117 180 copies-equivalent to an estimate of over 200 myxospores l(-1). Parasite DNA was generally not detected in August or September, the period with the highest water temperature. The reason for this observation is unknown, but the timing of parasite development may play a role. The amount of detected DNA was not different between unfiltered culture water and water filtered through a high-speed fiber filtration system. This result and the past incidence of high infection rate of fish reared in filtered water indicate that the mechanical removal of K. yasunagai from culture water is difficult. Detecting the precise onset and time window of infection in host fish will be an important step in the development of measures to control this economically important parasite. - Sho Shirakashi; Tomoyo Nishimura; Nagaharu Kameshima; Hiroshi Yamashita; Hiroe Ishitani; Katsuya Ishimaru; Hiroshi YokoyamaFish Pathology The Japanese Society of Fish Pathology 49 (3) 141 - 144 0388-788X 2014 [Refereed]
- Mark Polinski; Sho Shirakashi; Andrew Bridle; Barbara NowakFISH & SHELLFISH IMMUNOLOGY ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD 36 (1) 61 - 67 1050-4648 2014/01 [Refereed]
Infections by two blood fluke species, Cardicola orientalis and Cardicola opisthorchis, currently present the greatest disease concern for the sea-cage culture of Pacific bluefln tuna (PBT) - a species of high global economic importance and ecological concern. In this study, we aimed to rapidly, quantitatively, and differentially identify infections by these two parasite species in cultured PBT as well as identify potential host immune responses. Using real-time qPCR, we were successful in quantitatively detecting parasite-specific DNA from within host blood, gill, and heart tissues; positively identifying parasitic infections 44 days earlier than microscopy methods previously employed. Both gill and heart became heavily infected by both parasite species in PBT within two months of sea-cage culture, which was only mitigated by the administration of anthelmintic praziquantel. Nevertheless, fish were observed to mount an organ specific transcriptive immune response during infection that mirrored the relative quantity of pathogenic load. In heart, significant (3-6 fold) increases in IgM, MHC2, TCR beta, and IL-8 transcription was observed in infected fish relative to uninfected controls; whereas in the gills only IgM transcription was observed to be induced (11 fold) by infection. Interestingly, the relative quantity of IgM transcription was highly correlated to the relative abundance of C orientalis but not C opisthorchis DNA in the gill samples, even though this organ showed high prevalence of DNA from both parasite species. Taken together, these findings indicate that although ineffective at combating infection during primary exposure, a cellular immune response is mounted in PBT as a potential rejoinder to future Cardicola exposure, particularly against C. orientalis. Although future investigation into antibody effectiveness will be needed, this work provides valuable preliminary insight into host responsiveness to Cardicola infection as well as additional support for the need of anthelmintic treatment following primary parasite exposure during PBT culture. (C) 2013 Elsevier Ltd. All rights reserved. - Katsuya Ishimaru; Ryoma Mine; Sho Shirakashi; Eri Kaneko; Kazushige Kubono; Tokihiko Okada; Yoshifumi Sawada; Kazuo OgawaAQUACULTURE ELSEVIER SCIENCE BV 402 24 - 27 0044-8486 2013/07 [Refereed]
Blood flukes of the genus Cardicola cause significant problems in the bluefin tuna farming around the world. In Japan, the mortality of the juvenile Pacific bluefin tuna Thunnus orientalis (PBT) caused by C. orientalis and C. opisthorchis has become a serious issue in the tuna farming industry in recent years. Oral treatment with praziquantel (PZQ) is highly effective against blood flukes and is indispensable for sustainable tuna farming. To develop a proper and safe drug treatment procedure, we investigated the minimum effective dose and pharmacokinetics of PZQ in juvenile PBT. Juvenile tuna were orally administered various doses of PZQ (0, 3.75, 7.5, 15 and 30 mg/kg body weight (BW)) once a day for 3 consecutive days, and the occurrence of C. opisthorchis before and after the treatment was compared. A significant decrease in the number of flukes was observed in the 3.75 mg/kg group, and complete eradication of flukes was achieved at dosages of 7.5 mg/kg and greater. This result indicates that the minimal effective dose of PZQ for treating C. opisthorchis is between 3.75 and 7.5 mg/kg, which is less than 1/20 of the treatment dose used for treating the skin fluke Benedenia seriolae in yellowtail culture. We used high-performance liquid chromatography analysis to assess the temporal changes in the concentrations of PZQ in serum, muscle, the liver and the kidney after a single administration of PZQ at 15 mg/kg BW. The PZQ concentration in the tissues peaked between 0.5 and 1.5 h following administration, and PZQ was undetectable after 24 h. The highest serum concentration was 2.0 mu g/mL, which is likely to be the lethal dose for C. opisthorchis. These results suggest that PZQ treatment is a highly effective and relatively safe method to control blood flukes in the tuna farming industry. (c) 2013 Elsevier B.V. All rights reserved. - Sho Shirakashi; Chihaya Hirano; Hiroe Ishitani; Katsuya IshimaruAQUACULTURE ELSEVIER SCIENCE BV 402 19 - 23 0044-8486 2013/07 [Refereed]
Skin fluke infection is a major parasitic problem in the aquaculture industry. Present control measures such as bath treatments are effective for removing flukes from fish but require extensive labour and time. Moreover, bath treatments cause great stress to the fish, and occasionally lead to post-treatment mortality. Our ultimate goal is to develop a culture technique that prevents or lowers the chance of fish encountering larval skin flukes, thus reducing infection. However, little is known about when and where these infections occur on fish farms. We conducted a field experiment at a culture site to determine the diurnal pattern of skin fluke infection at different water depths. Juvenile amberjack, Seriola dumerili, were placed in enclosed mesh cages and exposed to skin flukes at depths of 0, 2 or 4 m for 4 h during different times of the day. A Neobenedenia girellae infection occurred predominantly at the surface during the mid-day. The infection rate declined considerably during the night. The parasite burden was significantly decreased with water depth, and up to an 80% and 95% reduction in intensities was observed when fish were exposed at a depth of 2 and 4 m, respectively. These results suggest that skin fluke infection can be significantly reduced by systematic management strategy and modification of culture techniques. (c) 2013 Elsevier B.V. All rights reserved. - Sho Shirakashi; Chihaya Hirano; Asmahani binti Asmara; Noorashikin binti Md Noor; Katsuya Ishimaru; Shigeru MiyashitaFish Pathology The Japanese Society of Fish Pathology 48 (1) 25 - 28 0388-788X 2013 [Refereed]
- Sho Shirakashi; Kazunobu Tsunemoto; Claire Webber; Kirsten Rough; David Ellis; Kazuo OgawaFish Pathology The Japanese Society of Fish Pathology 48 (1) 1 - 4 0388-788X 2013 [Refereed]
- Hiroshi Yokoyama; Shigehiko Urawa; Daniel Grabner; Sho ShirakashiPARASITOLOGY INTERNATIONAL ELSEVIER IRELAND LTD 61 (4) 594 - 598 1383-5769 2012/12 [Refereed]
Henneguya cartilaginis n. sp. (Myxozoa: Myxosporea) is described from wild masu salmon Oncorhynchus masou masou in Hokkaido, Japan. H. cartilaginis n. sp. produced white cysts, up to 3 mm in size, in the head of masu salmon. Infected fish exhibited cranial protrusion due to the cysts. Spores (11.4 x 8.6 mu m) of H. cartilaginis n. sp. were egg-shaped with the posterior end more pointed and possessed two caudal appendages (34.2 mu m average length). Histological observations revealed that large plasmodia possessing fine fibrous pseudopodia on the surface developed in the head cartilage. H. cartilaginis n. sp. resembles H. cerebralis, which was described from the cranial cartilage of Kosogol grayling Thymallus nigrescens in Mongolia. However, they were distinguishable by spore morphology. Molecular analysis of the 18S rDNA sequences indicated that H. cartilaginis n. sp. was most closely related to Henneguya zschokkei, H. nuesslini and H. salminicola of salmonid fish, with genetic similarities of 95.3%, 95.1% and 93.9%, respectively. Based on these differences in spore morphology, molecular data, the site of infection and geographical distribution, the present species is considered to be a new species. (C) 2012 Elsevier Ireland Ltd. All rights reserved. - Sho Shirakashi; Akinobu Morita; Katsuya Ishimaru; Shigeru MiyashitaDISEASES OF AQUATIC ORGANISMS INTER-RESEARCH 101 (2) 123 - 130 0177-5103 2012/11 [Refereed]
We monitored infection by a brain-infecting myxozoan Kudoa yasunagai in hatchery-reared juvenile yellowtail Seriola quinqueradiata at a culturing site in Japan. Infection was detected by PCR and microscopic observation once every 1 to 4 wk during 2010 and 2011. In both years, we detected first infection in mid-July by PCR. Prevalence increased rapidly after the onset of infection, peaking at 100% within 4 wk. Parasites required less than 10 d to reach the brain after invasion. Development of plasmodia and formation of cysts took 4 to 8 wk. Infection did not reach a plateau and number of cysts tended to decline over time, suggesting possible recovery from the infection. A drastic decline in infection prevalence was observed during the season of highest water temperature (>30 degrees C) in 2010. To understand this phenomenon, we conducted a laboratory experiment to compare infection prevalence and cyst formation in fish kept at 25 degrees C and 30 degrees C. However, we could not detect obvious differences between the treatment groups during the 4 wk of the experiment. There was no apparent pathology associated with the infection. These results suggest that pathological effects of K. yasunagai may differ between fish species or that other factors are important in the development of infectious signs. - H. Yokoyama; T. Yanagida; S. ShirakashiPARASITOLOGY RESEARCH SPRINGER 110 (6) 2247 - 2254 0932-0113 2012/06 [Refereed]
Kudoa ogawai n. sp. (Myxozoa; Multivalvulida) is described from the trunk muscle of Pacific barrelfish Hyperoglyphe japonica caught in Japan. Oval to ellipsoidal cysts, white to yellowish in colour, 1-2 mm in size, were filled with numerous spores having four polar capsules. Spores were stellate with rounded peripheral edges in apical view, and garlic shaped with four prominent apical projections in side view. Average (range) spore size was 13.3 (12.0-14.2) mu m in width and 9.0 (8.3-9.7) mu m in length. The spore dimensions and the apical projections of K. ogawai n. sp. were clearly distinguishable from the other muscle-infecting species. Molecular analyses of 18S rDNA and 28S rDNA sequences showed that K. ogawai n. sp. is closely related to Kudo iwatai and Kudoa hemiscylli (95% and 92% genetic similarity, respectively), but the present species is morphologically distinct from the two species. Phylogenetic analysis of 18S and 28S rDNA placed K. ogawai n. sp. sister to all Kudoa spp. available in GenBank. - Sho Shirakashi; Yoshiki Kishimoto; Ryuhei Kinami; Hiromitsu Katano; Katsuya Ishimaru; Osamu Murata; Naoki Itoh; Kazuo OgawaPARASITOLOGY INTERNATIONAL ELSEVIER IRELAND LTD 61 (2) 242 - 249 1383-5769 2012/06 [Refereed]
Infestations of blood flukes of the genus Cardicola have been observed in juvenile Pacific bluefin tuna (PBT) cultured in Japan. Infected fish harbor large numbers of parasite eggs in their gills. Although the link between blood fluke infection and juvenile mortality is not clear, accumulation of parasite eggs appears to be pathogenic to the fish. We investigated the origins, general morphology/distribution, and histopathology of these eggs in artificially produced 0 yr old PBT. Dead and live fish were sampled on several occasions from two culture facilities in Wakayama prefecture, Japan. The number of eggs in each gill filament was enumerated under a microscope. In addition, we estimated the total number of eggs by dissolving the gills in a weak NaOH solution. We observed two morphologically distinct egg types in the gill filaments, smaller, oval shaped eggs in the gill lamellae and larger, crescent shaped eggs that occurred primarily in the filamentary arteries. Based on the ITS2 sequence, the ovoid and crescent shaped eggs were identified as C on entails and C. opisthorchis, respectively. Eggs of the former species were more abundant (maximum: 6900 per filament) than the latter (maximum: 1400), but the number was highly variable among filaments. The eggs of the latter species were relatively evenly distributed among the filaments. In a heavily infected individual, we estimated a total of >4.5 million eggs were present in the gills on one side of the fish. The number of eggs from the two species was positively correlated to each other and the dead fish tended to harbor more eggs than the live fish. Histological observation revealed host responses around the eggs, including encapsulation by fibroblasts and nodule formation, as seen in response to other aporocotylid eggs. In addition, we observed widespread fusion of gill lamellae and blockage of the filamentary arteries in some instances. Our results provide information that can be used for routine diagnosis of Cardicola blood flukes in cultured tuna and suggest they represent a risk to juvenile PBT. (C) 2011 Elsevier Ireland Ltd. All rights reserved. - D. S. Grabner; H. Yokoyama; S. Shirakashi; R. KinamiAQUACULTURE ELSEVIER SCIENCE BV 338 36 - 40 0044-8486 2012/03 [Refereed]
Kudoa infections in muscle tissue can be a serious problem for fisheries and aquaculture of olive flounder (Paralichthys olivaceus) due to post-mortem myoliquefaction that makes the fish unmarketable. Recently, cases of a new food poisoning of human associated with ingestion of raw olive flounder infected with Kudoa septempunctata have increased in Japan. In the present study, diagnostic PCR assays were developed to detect and distinguish Kudoa spp. from olive flounder muscle. Kudoa 18S and 28S rDNA were amplified from infected fish by universal primers and sequenced. Blast searches with the obtained sequences revealed the presence of not only K. septempunctata and K. thyrsites, but also K. lateolabracis which was detected for the first time in olive founder. Comparison of the 28S rDNA sequences obtained from K. thyrsites isolated in the present study with a previous isolate from GenBank indicated the existence of two genetic lineages of this species, both infecting olive flounder. Alignments of partial 28S rDNA sequences were used to design primers for each of the three Kudoa spp. Specificity of each primer pair was tested by PCR with DNA from different myxozoans and host DNA. For sensitivity testing, the target sequence was ligated into a plasmid vector and cloned. PCR was conducted with host DNA spiked with dilution series of the plasmid. Additionally, a practical test of the primers was conducted in comparison to classical diagnostic methods with 10 olive flounders from a fish farm suspected to be infected with Kudoa spp. All three primer pairs were specific for the respective parasite and amplified neither host DNA nor DNA of other tested myxozoans. Primers for K. septempunctata approximately amplified down to 0.06. those for K. thyrsites 0.001 and for K. lateolabracis 0.1 spores per reaction (240, 4 and 400 spores per 1 g of muscle tissue). The diagnostic PCR assay developed in this study was shown to be more effective for detection of K. septempunctata from cultured olive flounder (10 out of 10 fish positive) than microscopic detection of spores in tissue homogenates (5 out of 10 fish positive). K. thyrsites and K. lateolabracis were not detected in the 10 flounders tested. This novel PCR assay will facilitate the screening and monitoring process for Kudoa infections and allow improved disease management in olive flounder aquaculture facilities. It will also improve food safety testing to avoid human consumption of Kudoa infected fillets. (c) 2012 Elsevier B.V. All rights reserved. - Nguang, S.I; Nakagawa, Y; Shirakashi, S; Kato, K; Murata, O; Takii, K; Miyashita, S; Senoo, SAquaculture Science 水産増殖談話会 60 (1) 1 - 9 0371-4217 2012 [Refereed]
Marble goby <I>Oxyeleotris marmoratus</I> is an important aquaculture freshwater (FW) species in Southeast Asia. To improve hatching technique, eggs from a river population in Sabah, Malaysia were incubated in FW and seawater (SW) diluted to 5, 10, 15, 20 and 30 psu, comparing hatching rates and larval deformation. Egg development, hatching rates, hatching periods, larval deformation and survival at 10 days after fertilization (dAF) were then compared in FW and 10 psu SW. Salinities from FW to 15 psu SW were tolerated, with the highest hatching observed at 10 psu SW (60.0±2.0%, mean±SD). Significantly higher hatching rates and lower deformation rates were observed at 10 psu SW than in FW. In FW, embryonic developed at similar rate with 10 psu SW, but hatching was delayed and all larvae died by 10 dAF. Peak of hatching in 10 psu SW observed in 48-60 hours after fertilization (hAF) (33.1±5.6%) while hatching in FW was delayed and peaked 72-84 hAF (10.6±3.4%). Larvae that hatched later had higher deformation rates. The eggs incubated in 10 psu SW had a shorter hatching period, higher hatching rate and better larval survival than those in FW. - Sho Shirakashi; Melanie Andrews; Yoshiki Kishimoto; Katsuya Ishimaru; Takahiko Okada; Yoshifumi Sawada; Kazuo OgawaAQUACULTURE ELSEVIER SCIENCE BV 326 15 - 19 0044-8486 2012/01 [Refereed]
Aquaculture of tuna has shown exponential growth in the recent years. In association with the global development of tuna aquaculture, problems with parasitic infections have arisen. Among the parasites found in cultured tuna, blood flukes are considered to be a significant threat as their eggs accumulate in the gills and interfere with the gas exchange process. To date, two species of blood fluke from the genus Cardicola have been found in Pacific bluefin tuna (Thunnus orientalis, PBT) cultured in Japan. We conducted an experiment to develop a drug treatment against the blood flukes of cultured tuna. Artificially produced juvenile tuna that were naturally infected with blood flukes were orally administered with anthelmintic praziquantel (PZQ) of 150, 15, 1.5 and 0 mg kg(-1) BW for three consecutive days, and differences in the abundance of adults and eggs in the gills were assessed. In the fish given 150 and 15 mg kg(-1) BW PZQ, adult worms in the heart ventricle were eradicated by day 8 post treatment with the number of eggs in the gills gradually declining over time. However, small numbers of adults re-appeared by week 3 or 5 post treatment. The drug does not seem to affect eggs as viable miracidia were observed throughout the experiment. Mortalities in the two lower dose groups were significantly higher than the groups in which PZQ doses were shown to be effective. The study empirically demonstrated the efficacy of PZQ on Cardicola blood flukes and that the parasite significantly affects the survival of juvenile PBT. The oral PZQ treatment may be an essential practice for sustainable aquaculture of PBT. (C) 2011 Elsevier B.V. All rights reserved. - Shinji Yamamoto; Sho Shirakashi; Satoshi Morimoto; Katsuya Ishimaru; Osamu MurataAQUACULTURE ELSEVIER 319 (1-2) 53 - 57 0044-8486 2011/09 [Refereed]
Outbreaks of skin flukes and associated mortalities have been observed in cultured chub mackerel, Scomber japonicus. Although freshwater bathing effectively removes the parasites, large post-treatment mortalities are occasionally observed especially under high water temperature conditions due to the stress from handling and confinement. Since outbreaks of the skin fluke infections often occur in high temperature seasons, development of an effective and safe control method is essential for the advancement of mackerel aquaculture. The present study aims to: 1) identify the skin fluke of cultured chub mackerel and 2) develop an alternative control measure using oral drug administration. The skin fluke was identified as Neobenedenia girellae by morphology and molecular data targeting ITS region of rDNA. Two trials of oral administration of praziquantel (PZQ), a common anthelmintic, were conducted and parasite intensity was compared before and after the treatment and between treated and untreated control fish. Fish rejected PZQ-coated commercial pellets, but oral administration was successfully achieved using frozen krill as a basal diet The three-day administration with a dose of 150 mg.kg(-1) BW.day(-1) resulted in over 80% reduction in worm intensity. However, some proportion of the skin flukes survived the drug treatment The resistance to PZQ does not relate to worm's developmental stage. Freshwater bathing was more effective and eradicated the parasite, but some post-treatment mortality of host fish was observed. Moreover, the parasite intensity drastically increased after the freshwater bathing, possibly due to stress and loss of mucus during the bathing. The study indicates the PZQ oral treatment is effective to control N. girellae in chub mackerel aquaculture when the drug is properly administrated with an appropriate feeding technique. (C) 2011 Elsevier B.V. All rights reserved. - K. Ogawa; K. Ishimaru; S. Shirakashi; I. Takami; D. GrabnerPARASITOLOGY INTERNATIONAL ELSEVIER IRELAND LTD 60 (3) 307 - 312 1383-5769 2011/09 [Refereed]
A new aporocotylid blood fluke is described, based on specimens from the ventricle of the Pacific bluefin tuna, Thunnus orientalis (Temminck et Schlegel), cultured in Wakayama and Nagasaki Prefectures, Japan. The new species is morphologically similar to the members of the genus Cardicola Short, 1953, but shows distinct differences in the body form, location of the testis and the orientation of the ootype. The body of the new species is long and slender, whereas other Cardicola species are small and generally lanceolate. The testis is mostly located posterior to the caeca and anterior to the ovary, occupying 31-45% of body length, in contrast to the known Cardicola species, whose testis is typically intercaecal. The ootype is oriented anteriorly, while in most congeners, it is directed posteriorly or horizontally. Phylogenetic analyses of this aporocotylid, together with Cardicola orientalis Ogawa, Tanaka, Sugihara et Takami, 2010 from the same host, were conducted based on DNA sequences of the ITS2 rDNA and the 28S region of ribosomal RNA. The analyses revealed that the new blood fluke belongs to the genus Cardicola despite the marked morphological differences. Thus, this aporocotylid is named Cardicola opisthorchis n. sp. and the generic diagnosis is emended in this paper. In addition, 100% identity among the ITS2 sequences from the present species, Cardicola sp. from T. orientalis in Mexico and Cardicola sp. from the northern bluefin tuna, Thunnus thynnus (Linnaeus) in Spain suggests that C. opisthorchis n. sp. has a broad geographical distribution and that it infects both the Pacific and northern bluefin tuna. (C) 2011 Elsevier Ireland Ltd. All rights reserved. - F. Meng; H. Yokoyama; S. Shirakashi; D. Grabner; K. Ogawa; K. Ishimaru; Y. Sawada; O. MurataPARASITOLOGY INTERNATIONAL ELSEVIER IRELAND LTD 60 (1) 90 - 96 1383-5769 2011/01 [Refereed]
Kudoa prunusi n. sp. (Myxozoa; Multivalvulida) is described from the brain of Pacific bluefin tuna Thunnus orientalis cultured in Japan. Numerous white cysts, up to 0.5 mm in size, were found on and in the brain. Spores having typically five spore valves and five polar capsules resembled a five-petal cherry blossom in apical view and were conical shape with a round bottom in side view. Average spore size was 9.63 (8.5-10.3)mu m in width and 7.50 (6.7-8.6)mu m in length. The spore dimensions of K. prunusi overlapped with those of Kudoa yasunagai ex Sillago ciliata having five to six spore valves, but they were clearly distinct in spore shape, 18S rDNA and 28S rDNA sequences (0.3% and 1.7% differences, respectively). Phylogenetic analysis of 18S rDNA revealed that K. prunusi grouped with the brain-infecting multivalvulid species, K. yasunagai, K. chaetodoni, K. lethrini and K. neurophila, rather than five-valved Kudoa spp. Combined with morphological, molecular and biological differences, K. prunusi was proven to be a new species. (C) 2010 Elsevier Ireland Ltd. All rights reserved. - Sho Shirakashi; Mansour El-MatbouliDISEASES OF AQUATIC ORGANISMS INTER-RESEARCH 89 (1) 63 - 70 0177-5103 2010/02 [Refereed]
Environmental pollutants alter a wide range of host-parasite interactions in various ways. In some cases, pollution leads to a significant increase in parasite abundance, causing epidemics of parasitic diseases. In other cases, toxicants restrict the transmission success of parasites, resulting in reduction of their abundance. However, very little is known regarding whether and to what extent aquatic pollution affects myxozoan obligate parasites commonly found in fish. We investigated the effect of cadmium (Cd) on the aquatic oligochaete Tubifex tubifex infected with the myxozoan Myxobolus cerebralis. The oligochaetes were experimentally exposed to M. cerebralis myxospores and kept in various concentrations of Cd for 4 mo. Neither survival nor reproduction of the worms was affected by the metal, but infection prevalence and numbers of triactinosmyxon spores produced by individual worms were higher in the Cd-exposed group than the unexposed control. A comparative assay of a lethal Cd concentration (LC50) on infected and non-infected T tubifex revealed that infected worms are more resistant to the acute toxicity of Cd, probably because uptake of Cd was reduced by the infection. These results suggest that the abundance of M. cerebralis likely increases in polluted waters and escalates the risk of whirling disease in the respective area. - Sho Shirakashi; Shuya Nakatsuka; Akihisa Udagawa; Kazuo OgawaFish Pathology The Japanese Society of Fish Pathology 45 (2) 51 - 57 0388-788X 2010 [Refereed]
- Tetsuya Yanagida; Sho Shirakashi; Takashi Iwaki; Noboru Ikushima; Kazuo OgawaPARASITOLOGY INTERNATIONAL ELSEVIER IRELAND LTD 58 (3) 308 - 310 1383-5769 2009/09 [Refereed]
To identify the metacercariae of a gymnophallid trematode in the Manila clam Ruditapes philippinarum from the Ariake Sea, experimental infection and molecular analysis were conducted. Based on the morphology of adult worms obtained from experimentally infected mice, the parasite was identified as Parvatrema duboisi. Comparison of internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) sequences for metacercariae and sporocysts from Manila clams and adult worms collected from wild wigeon Anas penelope showed minor differences ranging from 0 to 0.8%. These data strongly suggest that in the Ariake Sea, the parasite has a lifecycle using the Manila clam as the first and second intermediate hosts and wigeon as the definitive host. (C) 2009 Elsevier Ireland Ltd. All rights reserved. - S. Shirakashi; M. El-MatbouliPARASITOLOGY CAMBRIDGE UNIV PRESS 136 (6) 603 - 613 0031-1820 2009/05 [Refereed]
Myxobolus cerebralis is the causative agent of whirling disease that hats significant economical and ecological impacts oil trout populations. Although intensive studies have been conducted to understand its effects on mid interactions, with its fish host, only limited information is available about hose and to what extent M. cerebralis affects its oligochaete host, Tubifex tubifex. We investigated the effects of M. cerebralis on survival, growth, reproduction, and feeding activity of T. tubifex. Mature, immature and juvenile worms were exposed to myxospores mid their infection prevalence, mortality, sexual development, reproduction and spore production were compared with unexposed worms. The parasite affected neither survival nor growth but inhibited clitellar development and reduced cocoon production by over 80%. Numbers of actinospores released from Mature worms were nearly 9-fold higher than that of immature worms. When non-clitellated infected worms were kept at 30 degrees C for 4 days, spore release ceased and they re-developed a clitellum. These results suggest parasite-induced castration. Comparative monitoring of defecation rate revealed that M. cerebralis reduced feeding activity of T. tubifex by approximately 40%. Low energy intake and impaired energetic allocation may lie the underlying mechanism behind reduced fecundity of infected T. tubifex. - Sho Shirakashi; Toyohiro Nishioka; Kazuo OgawaFISHERIES SCIENCE SPRINGER JAPAN KK 75 (1) 121 - 128 0919-9268 2009/02 [Refereed]
We monitored feeding behavior and survival of starved juvenile olive flounder experimentally infected with the gill monogenean Neoheterobothrium hirame. Infected flounder increased amount of the time spent in the water column by 117% when trying to capture live mysids, Neomysis sp. They also showed different feeding patterns from those of uninfected fish and made fewer attacks towards prey during one feeding attempt. Although the average numbers of mysids captured by individuals were similar between infected and uninfected fish, heavily infected fish tended to catch less prey. These results indicate that N. hirame reduces the feeding efficiency of the host for capturing live prey and possibly makes them more vulnerable to predation during feeding. We could not detect any obvious difference in survival rates between uninfected, lightly and heavily infected fish during 3 months of starvation. There was no evidence that starvation makes fish more susceptible to N. hirame. The present study provides first experimental evidence that N. hirame affects feeding behavior of juvenile olive flounder and supports the idea that this parasite indirectly reducing the host's survival and may be responsible for the recent reduction of the flounder population in Japan. - Sho Shirakashi; Kazuhisa Teruya; Kazuo OgawaINTERNATIONAL JOURNAL FOR PARASITOLOGY ELSEVIER SCI LTD 38 (13) 1513 - 1522 0020-7519 2008/11 [Refereed]
Neoheterobothrium hirame is a blood feeding monogenean of olive flounder Paralichthys olivaceus. The parasite was first reported in the mid-1990s from the Sea of Japan and became epidemic within cultured and wild flounder populations after several years. Infected fish often suffer from severe anaemia and thus the parasite is thought to have played an important role in the recent depletion Of flounder populations in some areas of Japan. However, the causal mechanism underlying the parasite epidemic and decreases in host populations is unclear because apparently A hirame infection is not fatal to the host. Here, we tested the hypothesis that N. hirame indirectly reduces the survival of wild juvenile flounder by altering their behaviour and making them more susceptible to predation. We conducted a series of experiments to compare behaviours and predation susceptibility between experimentally infected juvenile P. olivaceus and uninfected fish. Results showed that X hirame infection increases the activity level, alters diel activity and has negative effects on burrowing performance and swimming endurance. When juvenile flounder cohabitated with predators, the survival rate of infected juveniles was approximately 25% less than that of uninfected fish. We believe this is the first empirical evidence linking N. hirame infection to death of the host through predation. Consequences of N. hirame-induced behavioural change for the survival of juvenile flounder in the wild are discussed. We conclude that recent outbreaks of N. hirame are likely to have been a key factor in the decline of flounder populations in Japan. (C) 2008 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved. - Jianping Fang; Sho Shirakashi; Kazuo OgawaFish Pathology The Japanese Society of Fish Pathology 43 (4) 144 - 151 0388-788X 2008 [Refereed]
- Koh-Ichiro Mori; Kazuhisa Yamamoto; Kazuhisa Teruya; Satoshi Shiozawa; Kenzo Yoseda; Takuma Sugaya; Sho Shirakashi; Naoki Itoh; Kazuo OgawaFISH PATHOLOGY JAPAN SOC FISH PATHOL DEPT FISHERIES-FAC AGR 42 (1) 49 - 57 0388-788X 2007 [Refereed]
Since 1990, mass mortality of fertilized eggs and hatched larvae of the leopard coral grouper Plectropomus leopardus has occurred repeatedly during its seed production in Okinawa Prefecture. A hitherto unknown protozoan parasite multiplied in the yolk sac in great numbers. The yolk sac of fertilized eggs and hatched larvae eventually burst and parasites were released to sea water. The development of the parasite was briefly described, which is very similar to that of the dinoflagellate Ichthyodinium chabelardi, known to infect yolk of several marine fish larvae in Europe. Based on the similarities of, and minor differences in, the mode of infection, development and SSU rDNA sequence, the parasite is tentatively designated as Ichthyodinium sp. PL (= PL for the abbreviated form of the scientific name for the host). Although the life cycle of the parasite is unknown, the disease outbreak was controlled by rearing the broodstock and incubating fertilized eggs in oxidant-treated seawater. The PCR diagnosis using specific primers designed from part of SSU rDNA sequence of the parasite revealed that disease outbreaks in different years were caused by a single species of parasite. This is the first report of Ichthyodinium infection in tropical fish from the Asia-Pacific region. - H. Yokoyama; S. ShirakashiBULLETIN OF THE EUROPEAN ASSOCIATION OF FISH PATHOLOGISTS EUR ASSOC FISH PATHOLOGISTS 27 (2) 74 - 78 0108-0288 2007 [Refereed]
Enteromyxum leei is an enteric myxozoan parasite that causes significant damage to cultured marine fishes in the world. Experimental infections with E. leei, using anemonefish (Amphiprion clarkii and A. ocellaris) as experimental host were conducted. Anemonefish were shown to be as susceptible to E. leei as tiger puffer and Japanese flounder. To evaluate the effects of hyposalinity on infectivity of E. leei, the developmental stages of E. leei collected from the intestinal mucosa of infected fish were exposed to different salinities of seawater or dechlorinated tapwater for 1 h. After the treatment, naive anemonefish were exposed to the parasite and checked for infection at 4 weeks post-exposure. The results indicated that treatment of low salinity below 1/4 seawater (8 parts per thousand) was effective for control of E. leei infection. - S. Shirakashi; T. Yamada; T. Yamada; K. OgawaJOURNAL OF FISH DISEASES WILEY-BLACKWELL PUBLISHING, INC 29 (6) 319 - 329 0140-7775 2006/06 [Refereed]
A recent epidemic of the invasive monogenean Neoheterobothrium hirame is suspected to have caused the significant decline of the commercial catch of olive flounder, Paralichthys olivaceus, in Japan. To clarify the causal link between parasite invasion and host depletion, we monitored the infections of N. hirame on juvenile flounder for 2 years at two widely separate bays, Obama Bay, experiencing a devastating reduction in flounder catches, and Miyako Bay with a stable catch. Prevalence, mean intensity and abundance of developmental stages of N. hirame were compared between the bays and between fish year classes. Fishes captured at Obama Bay harboured three times more worms than those at Miyako Bay and had a significantly higher overall prevalence of infection. In addition, there was a negative correlation between parasite intensity and host condition factor at Obama Bay, suggesting a causal link between the N. hirame epidemic and the reduction of local flounder populations. - S Shirakashi; CP GoaterPARASITOLOGY CAMBRIDGE UNIV PRESS 130 177 - 183 0031-1820 2005/02 [Refereed]
We monitored temporal changes in the magnitude of altered host behaviour in minnows (Pimephales promelas) experimentally infected with metacercariae of a brain-encysting trematode (Ornithodiplostomum ptychocheilus). This parasite develops and then encysts in a region of the brain that mediates the optomotor response (OMR), an innate behaviour that links visual stimuli with motor performance. The OMR of infected and uninfected minnows was evaluated between 0 and 10 weeks post-infection (p.i.), an interval spanning the development period of metacercariae to infectivity in birds. Trials involved monitoring the time an individual minnow spent following a spinning drum that had been painted with alternating black and white stripes. At 2 and 4 weeks p.i., infected minnows followed the drum 40% less often than controls. Differences between controls and infected fish declined thereafter, and were undetectable by 10 weeks p.i. Both control and infected fish habituated equally rapidly to the spinning drum. However, the difference in performance between controls and infected fish was 29% for experienced fish and 48% for fish that: had never experienced the drum. Because maximum parasite induced reduction in OMR coincided with the period of maximum parasite development, the behavioural effects are most likely due to unavoidable pathology in the brain associated with developing larvae. - Sho Shirakashi; Tomoyoshi Yoshinaga; Masakazu Oka; Kazuo OgawaFish Pathology The Japanese Society of Fish Pathology 40 (1) 33 - 35 0388-788X 2005 [Refereed]
- Sho Shirakashi; Cameron P. GoaterThe Journal of Parasitology JSTOR 88 (6) 1071 - 1071 0022-3395 2002/12 [Refereed]
- S Shirakashi; CP GoaterECOSCIENCE UNIVERSITE LAVAL 8 (3) 289 - 293 1195-6860 2001 [Refereed]
Many populations of fathead minnows (Pimephales promelas Rafinesque) in northern Alberta, Canada, contain individuals with hundreds of trematode (Ornithodiplostomum ptychocheilus Faust) cysts on the surface of their brains. Most cysts are located on the optic tecta, a region known to play a role in integrating visual and motor stimuli, especially in schooling fish. We determined the effect of infection on visually-mediated behaviours of fathead minnows by evaluating host performance in an optomotor swimming task. Monitoring this task involved recording the time minnows spent following a spinning drum, onto which alternating black and white stripes had been painted. After controlling for host activity and host size, minnows containing an average of 18 (low-intensity) or 98 larvae (high-intensity) reduced their time spent following the spinning drum by 42% and 26%, respectively, compared to uninfected controls. Low-intensity minnows also took longer than controls to respond to a change in the direction of the spinning drum. Reduced optomotor performance has the potential to affect a host's ability to detect and respond to prey, predators and conspecifics.
MISC
- Yamamoto Michitaka; Sugahara Kazuhiro; Asai Nanami; Yanagida Tetsuya; Yokoyama Hiroshi; Shirakashi Sho Fish Pathology 58- (2) 60 -70 2023/06
- 榊原舞; 白樫正; 青木隆一郎; 升間主計; 中村修; 筒井繁行 日本魚病学会大会プログラムおよび講演要旨 2023- 2023
- 白樫 正; 杉原 志貴 養殖ビジネス = Aqua culture business 59- (6) 20 -24 2022/05
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- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 白樫正 魚類防疫技術書(Web) 2020- 2021
- 山本充孝; 白樫正; 浅井七望; 柳田哲矢; 横山博 滋賀県水産試験場事業報告 2019- 2021
- 白樫 正 養殖ビジネス = Aqua culture business 57- (2) 26 -29 2020/02
- 白樫正 月刊養殖ビジネス 57- (2) 2020
- 横山博; 白樫正; 山本充孝; 浅井七望 近畿大学水産研究所報告(Web) (20) 2020
- 八木洋樹; 浅井七望; 白樫正; 岡田貴彦; 高岡治; 升間主計 魚病研究 55- (3) 2020
- 白樫正 月刊養殖ビジネス 55- (10) 15 -18 2018
- 小川和夫; 白樫正 月刊養殖ビジネス 55- (13) 4 -8 2018
- 白樫正; 小川和夫 月刊養殖ビジネス 55- (13) 16 -20 2018
- 白樫 正 魚病研究 = Fish pathology 52- (4) 172 -176 2017/12
- Kazuo Ogawa; Sho Shirakashi FISH PATHOLOGY 52- (4) 186 -190 2017/12 [Refereed]
- 山内岬; 白樫正 沖縄県水産海洋技術センター事業報告書(Web) (76) 2017
- 白樫正 日本水産学会誌 83- (5) 829 -829 2017
- Sho Shirakashi; Kazuo Ogawa FISH PATHOLOGY 51- (3) 92 -98 2016/09
- 白樫 正; 小川 和夫 アクアネット = Aqua net : 産地と消費地をネットする水産情報誌 19- (6) 44 -49 2016/06
- Sho Shirakashi NIPPON SUISAN GAKKAISHI 81- (5) 875 -875 2015/09
- 白樫 正 アクアネット = Aqua net : 産地と消費地をネットする水産情報誌 18- (6) 25 -27,18 2015/06
- SHIRAKASHI SHO 日本水産學會誌 = Bulletin of the Japanese Society of Scientific Fisheries 75- (3) 475 -476 2009/05
Books and other publications
- 和田, 新平 (Contributor第12章大型寄生虫病)緑書房 2024/01 9784895319423 191p
- 小川, 和夫; 飯田, 貴次 (Contributor大型寄生虫病)恒星社厚生閣 2020/09 9784769916543 x, 192p, 図版 [4] p
- 横山, 博; 有路, 昌彦; 大石, 卓史; 大南, 絢一; 白樫, 正 (Contributor原虫および大型寄生虫の検体保存と輸送方法)緑書房 2020/04 9784895313643 159p
- 近畿大学水産研究所 (Contributor病気の対策と課題; 病気の原因)日刊工業新聞社 2019/02 9784526079443 159p
- 農学とはなにか小川一夫; 白樫正 (Contributor水産学)2018
- Jimena Balli; Ivona Mladineo; Sho Shirakashi; Barbara F. Nowak (Joint work)Elsevier Inc. 2015/01 9780124114593This chapter describes diseases in ranched and farmed bluefin tunas. Blood fluke infection, caused by three different species from genus Cardicola is the main problem in ranching in Australia and farming in Japan. These infections have been managed using praziquantel applied as oral treatment. Swimmer syndrome caused by a scuticociliate Uronema nigricans caused mortalities in southern bluefin tuna (SBFT) but does no longer appear to be an issue. Photobacterium damsela subsp. piscicida caused mortalities in ranched Atlantic bluefin tuna (ABFT) in 2003 and 2004. Closing life cycles for SBFT and ABFT will result in more health issues as naïve fish from hatcheries will be transferred to marine cages, as has been witnessed for hatchery-reared Pacific bluefin tuna (PBFT) in Japan. Intensification of ranching and global challenges may contribute to other health problems. While there are some species-specific and regional differences there are many common issues suggesting effectiveness of international research collaborations.
- Hiroshi Yokoyama; Daniel Grabner; Sho Shirakashi (Joint work)InTech 2012/04 9789535104971
Lectures, oral presentations, etc.
- 海産魚類養殖の寄生虫対策 [Invited]白樫正大分県令和6年度魚類養殖講習会 2024/07
- 和歌山県で分離した海産白点虫 3 株の遺伝子配列と性質の比較松岡大海; 小竹真帆; 本領智記; 白樫 正; 良永知義; 伊藤直樹; 渡邊勇歩令和6年度日本魚病学会春季大会 2024/03
- 吸虫性旋回病原因寄生虫Galactosomum sp.の第1中間宿主の特定杉原志貴; 岩﨑亮磨; 宮﨑悠暉; 小川和夫; 髙野剛史; 白樫 正; 伊藤直樹; 中野智之令和6年度日本魚病学会春季大会 2024/03
- 虫卵を摂食する魚類を用いたハダムシ防除効果の検討冨田雄貴; 白樫正; 服部亘宏; 小川和夫令和6年度日本魚病学会春季大会 2024/03
- マダイイリドウイルス病発生時に死魚を扱った養殖資機材は高濃度に汚染されている河東康彦; 髙田優三; 松山知正; 本領智記; 白樫 正; 升間主計令和6年度日本魚病学会春季大会 2024/03
- アマゴ魚体内における微胞子虫Inodosporus fujiokaiの挙動について米加田徹; 秋元勇毅; 安東秀容; 横山博; 菅原和宏; 山本充孝; 木南竜平; 白樫 正; 柳田哲矢令和6年度日本魚病学会春季大会 2024/03
- マダイ親魚における生殖腺線虫の寄生実態令和5年度日本魚病学会秋季大会 2023/09
- 養殖種苗の寄生虫病対策 [Invited]白樫正第18 回 種苗生産技術交流会 2023/08
- ハダムシがカンパチの代謝量および遊泳行動に及ぼす影響表原陸; 川崎亜美; 山本剛; 白樫正; 鳥澤眞介; 光永靖令和5 年度日本水産学会春季大会 2023/03
- ハタ科魚類2種およびその交雑種の体表粘液レクチンとマハタハダムシへの影響榊原舞; 白樫正; 青木隆一郎; 升間主計; 中村修; 筒井繁行令和 5年度日本魚病学会春季大会 2023
- 微胞子虫Inodosporus fujiokaiの魚種別感受性の比較による養殖魚のリスク評価菅原和宏; 山本充孝; 金理求; 木南竜平; 白樫正; 柳田哲矢; 米加田徹; 横山博日本魚病学会大会プログラムおよび講演要旨 2023
- スジエビ寄生微胞子虫の魚類への感染様態の解明と定量感染実験系の開発木南竜平; 金理求; 白樫正; 菅原和宏; 山本充孝; 柳田哲矢; 横山博日本魚病学会大会プログラムおよび講演要旨 2022
- 日本の養殖で問題となるハダムシ6種の同時検出PCRプライマーの開発阿川泰夫; 日原麻衣; 澤田好史; 白樫正; 水落裕貴; 小川和夫日本水産学会大会講演要旨集(CD-ROM) 2021
- ニジマスの筋肉微胞子虫症(感染源の推定)山本充孝; 白樫正; 浅井七望; 柳田哲矢; 横山博日本魚病学会大会プログラムおよび講演要旨 2021
- 海産白点虫プロテアーゼの感染防御抗原としての有効性渡邊勇歩; HUI How Kah; 善家孝介; 今城雅之; 白樫正; 伊藤直樹; 良永知義日本魚病学会大会プログラムおよび講演要旨 2021
- ハダムシNeobenedenia girellaeミトコンドリアゲノム上のデータベースにない新規配列について阿川泰夫; 日原麻衣; 澤田好史; 白樫正日本水産学会大会講演要旨集 2020
- Neobenedenia girellaeに対するワクチン抗原遺伝子探索のための発達段階別トランスクリプトーム解析田邉勇樹; 川戸智; 野崎玲子; 白樫正; 近藤秀裕; 廣野育生日本魚病学会大会プログラムおよび講演要旨 2020
- マダイイリドウイルス国内流行株の分子疫学解析河東康彦; 米加田徹; 桐生郁也; 松山知正; 白樫正; 勝田芳樹; 升間主計; 水野かおり; 山本千晶; 原川翔伍; 川上秀昌日本魚病学会大会プログラムおよび講演要旨 2020
- ハダムシ・エラムシ孵化幼生の光に対する反応浅井七望; 三浦真由子; 白樫正日本水産学会大会講演要旨集 2019
- 銅合金網による単生類虫卵の孵化阻害効果白樫正; 小鍛治莉子; 三浦真由子; 山本修平日本魚病学会大会プログラムおよび講演要旨 2019
- 水族館におけるハダムシの多様性浅井七望; 白樫正; 矢野渚; 柳澤牧央; 小川和夫日本魚病学会大会プログラムおよび講演要旨 2019
- ブリ類のべこ病の疫学調査(感染時期・場所の把握と中間宿主の探索)柳宗悦; 福留慶; 宍道弘敏; 川上秀昌; 原川翔伍; 石井佑治; 白樫正; 佐藤純; 米加田徹; 桐生郁也; 森広一郎; 中易千早日本魚病学会大会プログラムおよび講演要旨 2019
- クロマグロを用いたマダイイリドウイルス病の感染試験法の検討松浦雄太; 西岡豊弘; 嶋原佳子; 佐藤純; 高野倫一; 寺島祥子; 松山知正; 久門一紀; 白樫正; 升間主計日本魚病学会大会プログラムおよび講演要旨 2019
- 海産アユ仔稚魚にみられたメタセルカリアについて白樫正; 浅井七望; 脇司; 小川和夫日本魚病学会大会プログラムおよび講演要旨 2019
- 新交雑種クエタマ(クエ♀×タマカイ♂)のマハタハダムシBenedenia epinepheliに対する抵抗性中田久; 家田一輝; 白樫正; 村田修; 升間主計日本水産学会大会講演要旨集 2018
- ブリ類のべこ病治療薬の探索 [Not invited]柳宗悦; 福留慶; 和田和彦; 佐藤純; 坂井貴光; 米加田徹; 山崎雅俊; 伊東尚史; 西岡豊弘; 森広一郎; 川上秀昌; 原川翔伍; 白樫正平成30年度日本魚病学会春季大会 2018 東京海洋大学
- 水産用経口駆虫剤によるべこ病治療効果とフェバンテルのブリ稚魚に対する毒性 [Not invited]白樫正; 浜野祥吾; 原川翔伍; 川上秀昌; 柳宗悦; 佐藤純; 三輪理; 森広一郎平成30年度日本魚病学会春季大会 2018 東京海洋大学
- 新交雑種クエタマ(クエ♀×タマカイ♂)のマハタハダムシBenedenia epinepheli に対する抵抗性 [Not invited]中田久; 家田一輝; 白樫正; 村田修; 升間主計平成30年度日本水産学会春季大会 2018 東京海洋大学
- ブリのべこ病に対するフェバンテルの有効な投与法 [Not invited]原川翔伍; 川上秀昌; 柳宗悦; 白樫正; 佐藤純; 森広一郎平成30年度日本魚病学会春季大会 2018 東京海洋大学
- Light-response larval behavior in three capsalid monogeneans [Not invited]S. Shirakashi; M. MiuraThe 93rd Annual Meeting of the American Society of Parasitologists 2018 The Marriott Cancun Resort
- POSSIBILITY FOR NON-DRUG CONTROL OF BLOOD FLUKE INFECTIONS IN FARMED BLUEFIN TUNA [Not invited]S. Shirakashi; T. Honryo; M. Kawahara; K. OgawaAQUA 2018 2018 Le Corum, Montpellier
- Cardicola orientalis, the blood fluke of Pacific bluefin tuna, in the polychaete intermediate host [Not invited]K. Ogawa; S. Shirakashi; T. Honryo; H. o. Uchida14th International congress of parasitology 2018 EXCO, Daegu Korea
- 天然クサフグにみられたKudoa septempunctata寄生の報告白樫正; 米加田徹; 佐藤純; 西岡豊弘; 森広一郎; 申相弼日本魚病学会大会プログラムおよび講演要旨 2017
- 病原体の生態および感染機構の解明と疾病防除 [Not invited]白樫正; 石丸克也平成28年度私立大学戦略的研究基盤形成支援事業プロジェクト「魚類の完全養殖の高度化」シンポジウム 2017 近畿大学農学部
- 単生類の生存戦略 [Not invited]白樫正平成29年度日本水産学会春季大会ミニシンポジウム「寄生虫症を宿主の視点から考える」 2017 東京海洋大学
- 研究奨励賞受賞講演「養殖種苗の寄生虫病対策に関する研究」 [Not invited]白樫正平成29年度日本魚病学会春季大会 2017 日本大学生物資源科学部
- ハダムシ類のミトコンドリアDNAおよび核ゲノム塩基配列の比較 [Not invited]小林圭吾; 白樫正; 杉原志貴; 福田譲; 山下浩史; 廣野育生; 近藤秀裕平成29年度日本魚病学会秋季大会 2017 ホテルメリージュ宮崎
- 海水中のハダムシNeobenedenia girellae孵化幼生検出法開発 [Not invited]阿川泰夫; 谷和樹; 山本修平; 平野千早; 澤田好史; 白樫正平成29年度日本水産学会春季大会 2017 東京海洋大学
- カンパチにおける種苗サイズによるべこ病発症率の違いとシスト数の長期変化傾向 [Not invited]浜野祥吾; 白樫正; 有元操; 森広一郎平成28年日本魚病学会秋季大会 2016 近畿大学農学部
- ハダムシBenedenia epinepheliふ化幼生の光刺激に対する反応 [Not invited]三浦真由子; 石丸克也; 石谷浩江; 白樫正平成28年日本魚病学会秋季大会 2016 近畿大学農学部
- クロマグロの住血吸虫(Cardicola opisthorchis)に対するプラジクアンテルの臨床試験 [Not invited]久保埜和成; 石丸克也; 白樫正; 小川和夫; 小田憲司H28年度日本魚病学会春季大会 2016 日本獣医生命科学大学
- Temporal and spatial infection patterns of tuna blood flukes Cardicola spp. in polychaete intermediate hosts at a tuna farm in Japan [Not invited]S. Shirakashi; K. Tani; K. Ishimaru; T. Honryo; H. Uchida; K. Ogawa91st Annual Meeting, American Society for Parasitologists 2016 The Westin Edmonton
- Preventing Kudoa infections in hatchery [Not invited]S. ShirakashiAquaculture Europe 2016 Edinburgh International COnference Centre
- ハダムシNeobenedenia girellaeの産卵生態と養殖生簀網における虫卵分布 [Not invited]平野千早; 石丸克也; 白樫正平成27年度日本水産学会春季大会 2015 東京海洋大学
- べこ病に罹患したカンパチ稚魚における体表のべこ症状とシストの関係 [Not invited]浜野祥吾; 石谷浩江; 白. 正平成27年度日本水産学会春季大会 2015
- 養殖クロマグロで見られる住血吸虫とその生活環 [Not invited]白樫正; 谷和樹; 石丸克也; 本領智記; 内田紘臣; 小川和夫H27年度日本魚病学会秋季大会 2015 東京大学農学部
- カナダ・イギリス・ドイツにおける水生動物の寄生虫に関する留学および在外研究 [Not invited]白樫正平成27年度日本水産学会春季大会ミニシンポジウム「若手が拓く水産学研究:国際舞台で活躍する若手研究者たち」 2015 東京海洋大学
- マグロ住血吸虫の中間宿主フサゴカイの分布状況と寄生の季節変動 [Not invited]谷和樹; 白樫正; 石丸克也; 本領智記; 内田紘臣; 小川和夫H27年度日本魚病学会秋季大会 2015 東京大学農学部
- クロマグロ養殖生簀周辺のフサゴカイに寄生していた住血吸虫(予報) [Not invited]谷和樹; 白樫正; 石丸克也; 本領智記; 内田紘臣; 小川和夫平成27年度日本魚病学会春期大会 2015 東京海洋大学
- 飼育水処理によるKudoa yasunagai防除法の検討および発症軽減に対する効果 [Not invited]西村知代; 白樫正; 中務寛; 赤井茜H27年度日本魚病学会秋季大会 2015 東京大学農学部
- Reproduction and inectious biology of Capsalid Monogenea Neobenedenia gireallae [Not invited]S. Shirakashi; C. Hirano; K. Ogawa9th International Symposium of Fish Parasites 2015 Valencia, Spain
- Phylogenetic study of the genus Kudoa using Baysian tip-association significance testing (BaTS) [Not invited]S. P. Shin; S. Shirakashi平成27年度日本魚病学会秋季大会 2015 東京大学大学院 農学生命科学研究科
- Investigation of the immune response during infection with two Cardicola species in farmed Pacific bluefin tuna juveniles [Not invited]Y. Pennacchi; A. Bridle; S. Shirakashi; M. Polinski; B. Nowak13th Congress of International Society of Developmental and Comparative Immunology 2015 Murcia, Spain
- The life cycle of Cardicola orientalis (Digenea: Aporocotylidae), a blood fluke of Pacific bluefin tuna [Not invited]K. Ogawa; S. Shirakashi; H. Uchida; S. Shin; K. Tani9th International Symposium of Fish Parasites 2015 Valencia, Spain
- Comparative study of parasites in Pacific bluefin tuna, yellowfin tuna and others Scombrid fishes from Panam? [Not invited]L. Lasso, T; S. Shirakashi; A. CanoSATREPS International Symposium 2015 Smithsonian Tropical Research Institute, Panama City, Panama
- ハダムシNeobenedenia girellaeの産卵とふ化の日周リズム [Not invited]平野千早; 白樫正; 石丸克也平成26年度日本魚病学会春期大会 2014 函館国際ホテル
- マサバ養殖におけるハダムシ防除法の比較 [Not invited]白樫正; 福島敦彦; 石丸克也; 山本眞司平成26年度日本魚病学会春期大会 2014 函館国際ホテル
- クロマグロ住血吸虫に対する(特異)抗体価の測定 [Not invited]谷和樹; 石丸克也; 白. 正; 小川和夫平成26年度日本魚病学会春期大会 2014 函館国際ホテル
- 飼育水のUV照射によるクドア寄生防除 [Not invited]西村知代; 白樫正; 亀島長治; 山下洋; 石谷浩江; 山博平成26年度日本魚病学会春期大会 2014 函館国際ホテル
- Kudoa (Myxozoa: multivalvulida) infections in cultured pacific bluerin tuna in Japan [Not invited]S. Shirakashi; J. Suzuki; H. YokoyamaWorld Aquaculture Adelaide 2014 2014 Adelaide convention centre
- Shading of culture cage reduces the infection of skin fluke Neobenedenia girellae [Not invited]S. Shirakashi; C. Hirano; A. Fukushima; K. OgawaICOPAXIII 2014 Camino Real Hotel, Mexico city, Mexico
- Transcriptional immune response of cage-cultured Pacific bluefin tuna during infection by two Cardicola blood fluke species [Not invited]M. Polinski; S. Shirakashi; A. Bridle; B. NowakInternational Symposium on Aquatic Animal Health 2014 Portland, Oregon
- 養殖場における水深・時間帯別のネオベネデニア寄生 [Not invited]平野千早; 白樫正; 石丸克也平成25年度日本魚病学会春期大会 2013 神奈川県藤沢市日本大学生物資源科学部湘南キャンパス
- クドア属粘液胞子虫の生態に関する基礎的検討 [Not invited]白樫正; 松浦巧; 南裕也; 常本和伸; 石丸克也平成25年度日本魚病学会春期大会 2013 神奈川県藤沢市日本大学生物資源科学部湘南キャンパス
- ハダムシNeobenedenia girellaeの生態 [Not invited]白樫正; 小川和夫第73 回日本寄生虫学会東日本支部大会 2013 国立科学博物館上野本館
- ハダムシNeobenedenia girellaeの交接行動 [Not invited]小川和夫; 白樫正; 石谷浩江平成25年度日本魚病学会秋期大会 2013 三重大学
- プラジクアンテルを用いたネオベネデニア防除の検討 [Not invited]山本眞司; 森本智; 白樫正; 石丸克也; 家戸敬太郎; 村田修; 升間主計; 宮下盛第11回 因島種苗生産技術交流会 2013 広島県尾道市因島
- ブダイにおけるクドア属粘液胞子虫の寄生 [Not invited]山根弘士; 白樫正; 横山博; 石谷浩江; 柳田哲也平成25年度日本魚病学会秋期大会 2013 三重大学
- Control of parasitic diseases in cultured Pacific bluefin tuna [Not invited]S. Shirakashi; K. Ishimaru; K. OgawaAquaculture conference: To the Next 40 Years of Sustainable Global Aquaculture 2013 Palacio de Congresos de Canarias, Las Palmas, Gran Canaria
- Skin fluke infection in culturing cages-possibilities for ecological control measure- [Not invited]S. Shirakashi; C. Hirano; A. b. Asmara; N. b; Md NooAnnual international seminar on marine science and aquaculture 2013 2013 Kota Kinabaru Sabah, Malaysia
- Our approach to the Kudoa problems: a case study in hatchery and culture facility [Not invited]S. Shirakashiクドア専門家セミナー 2013 韓国釜山
- New possibilities of reducing skin fluke infection in net cage mariculture [Not invited]S. ShirakashiASP Parasitic Diseases in Fish Mariculture Workshop 2013 Launceston, Tasmania, Australia
- Host-pathogen interaction in blood fluke infection in Pacific bluefin tuna [Not invited]M. Polinski; S. Shirakashi; A. Bridle; B. Nowak16th European Association of Fish Pathology Internation Conference on Diseases of Fish and Shellfish 2013 Tampere, Norway
- Development of a new method to reduce Neobenedenia girellae infection [Not invited]C. Hirano; S. ShirakashiAquaculture conference: To the Next 40 Years of Sustainable Global Aquaculture 2013 Palacio de Congresos de Canarias, Las Palmas, Gran Canaria
- 定量PCRを用いた海水からのKudoa yasunagai検出法の確立 [Not invited]白樫正; 松浦巧; 常本和伸; 石丸克也H24年日本魚病学会秋季大会 2012 山口県下関市 水産大学校
- 水深別のブリハダムシBenedenia seriolae寄生数の変化 [Not invited]白樫正; 呉秀賓; 石丸克也; 宮下盛平成24年度日本魚病学会春期大会 2012 東京都品川区 東京海洋大学
- クロマグロ住血吸虫に対するプラジクアンテルの最低有効量と体内動態 [Not invited]石丸克也; 峰龍馬; 白樫正; 宮下盛平成24年度日本魚病学会春期大会 2012 東京都品川区 東京海洋大学
- オーストラリアの蓄養ミナミマグロにみられた住血吸虫の同定 [Not invited]小川和夫; 白樫正; 常本和伸; C. Webber; K. RoughH24年日本魚病学会秋季大会 2012 山口県下関市 水産大学校
- Control of blood fluke infection in cultured Pacific bluefin tuna, Thunnus orientalis, in Japan [Not invited]S. Shirakashi; K. Ishimaru; T. Okada; Y. Sawada; K. Ogawa2012 Australian Society for Parasitology 2012
- Parasitic diseases of cultured Pacific bluefin tuna Thunnus orientalis and development of control measure [Not invited]S. Shirakashi; K. Ishimaru; T. Okada; Y. Sawada; S. MiyashitaWorld Aquaculture Society 2012 Las Vegas, USA
- Effect of water depth and diurnal pattern of skin fluke infection in cultured amberjack [Not invited]S. Shirakashi; C. Hirano; K. IshimaruInternatinal symposium of Kinki University in Kushimoto 2012 Kushimoto, Wakayama Japan
- クロマグロに寄生する2種の住血吸虫Cardicola orientalis及びC. sp.虫卵の組織病理学的研究 [Not invited]木南竜平; 白樫正; 岸本喜樹; 小川和夫平成23年度日本魚病学会春季大会 2011 東京都文京区 東京大学農学部
- クロマグロ住血吸虫に対するプラジクアンテルの有効性について [Not invited]白樫正; M. Andrews; 石丸克也; 岡田貴彦; 村田修; 岸本喜樹; 小川和夫平成23年度日本魚病学会春季大会 2011 東京都文京区 東京大学農学部
- 魚類の住血吸虫に対するプラジクアンテルのin vitroでの殺虫効果 [Not invited]孫暁楠; 良永知義; 土井啓行; 白樫正; 石丸克也; 小川和夫平成23年度日本魚病学会春季大会 2011 東京都文京区 東京大学農学部
- 養殖場における脳クドアの感染動態と病理組織 [Not invited]森田明伸; 白樫正; 石丸克也; 村田修平成23年度日本水産学会春期大会 2011 東京都品川区 東京海洋大学
- PCR法を用いた脳寄生クドアの検出と養殖場における感染動態 [Not invited]森田明伸; 白樫正; 石丸克也; 宮下盛平成23年度日本水産学会秋季大会 2011 長崎大学
- 虫卵を指標としたクロマグロ住血吸虫2種の寄生状況 [Not invited]岸本喜樹; 小川和夫; 白樫正; 高見生雄平成23年度日本魚病学会春季大会 2011 東京都文京区 東京大学農学部
- Kudoa septempunctata (Myxozoa: Multivalvulida) from the trunk muscle of cultured olive flounder (Paralichthys olivaceus) causing the food poisoning of human [Not invited]H. Yokoyama; D. Grabner; S. Shirakashi; R. Kinami8th International Symposium on Fish Parasites 2011 The Gala Hotel, Vi?a del Mar, Chile
- Control of blood fluke infections in cultured Pacific bluefin tuna, Thunnus orientalis [Not invited]S. Shirakashi; K. Ishimaru; T. Okada; K. Ogawa8th International Symposium on Fish Parasites 2011 The Gala Hotel, Vi?a del Mar, Chile
- 養殖クロマグロ稚魚に見られた住血吸虫と粘液胞子虫について [Not invited]白樫正; 石丸克也; 岡田貴彦; 澤田好史; 宮下盛; 村田修; 横山博; 小川和夫平成22年度日本水産学会春季大会 2010 神奈川県藤沢市 日本大学生物資源科学部
- 養殖クロマグロでみられる寄生虫とその防除方法の開発 [Not invited]白樫正近畿大学グローバルCOE プログラム平成22 年度成果報告シンポジウム 2010 東大阪市 近畿大学
- 養殖クロマグロには2種の住血吸虫が寄生する [Not invited]小川和夫; 白樫正; 石丸克也; 村田修平成22年度日本魚病学会秋季大会 2010 三重大学生物資源学部
- Myxosporean and microsporidian infections in cultured Pacific bluefin tuna Thunnus orientalis in Japan [Not invited]H. Yokoyama; J.-Y. Zhang; F. Meng; K. Ogawa; J. Miyara; I. Takami; S. Shirakashi; K. Ishimaru; Y. Sawada; O. MurataThe XIIth International Congress of Parasitology 2010 Exhibition and Convention Centre, Melbourne, Australia
- Parasitic infections observed in artificially bred Pacific bluefin tuna, Thunnus orientalis [Not invited]S. Shirakashi; K. Ishimaru; Y. Sawada; O. Murata; H. Yokoyama; K. OgawaFrench-japanese Symposium Kinki Ifremer 2010 2010 S?te, France
- Two species of sanguinicolid blood flukes from cultured Pacific bluefin tuna Thunnus orientalis [Not invited]S. Shirakashi; K. Ishimaru; Y. Sawada; O. Murata; N. Itoh; K. OgawaThe XIIth International Congress of Parasitology 2010 Exhibition and Convention Centre, Melbourne, Australia
- Parasitic infection in cultured Pacific bluefin tuna, Thunnus orientalis [Not invited]S. Shirakashi; K. Ishimaru; T. Okada; Y. Sawada; S. Miyashita; O. Murata; H. Yokoyama; K. OgawaAnnual Seminor on Marine Science & Aquaculture 2010 Universiti Malaysia Sabah
- Effects of cadmium on Myxobolus cerebralis infection on Tubifex tubifex [Not invited]S. Shirakashi; M. El-Matbouli14th European Association of Fish Pathologists International Conference 2009 Prague Czech Republic
- アサリ寄生Gymnophallidae 科吸虫は二宿主性生活環を持つ [Not invited]柳田哲矢; 白樫正; 巌城隆; 小川和夫第77回日本寄生虫学会大会 2008
- Myxobolus cerebralis (Myxozoa) reduces reproduction and feeding rate of its oligochaete host Tubifex tubifex [Not invited]S. Shirakashi; M. El-Matbouli5th International Symposium of the Japanese Society for Fish Pathology 2008 Tokyo, Japan
- Ribosomal RNA gene sequence indicates the two-host lifecycle of Gymnophallid digenean from Manila clam. [Not invited]T. Yanagida; S. Shirakashi; T. Iwaki; K. Ogawa7th International Symposium on Fish Parasitology 2007 Viterbo, Italy
- Evaluation of hyposalinity treatment on infection with Enteromyxum leei (Myxozoa), by using anemonefish Amphiprion spp. as an experimental host [Not invited]H. Yokoyama; S. ShirakashiThe 11th International Congress for Parasitology 2006 The Scottish Exhibition and Conference Centre (SECC), Glasgow Scotland UK
- 第7回シンポジウム「水生動物の行動と神経系」 [Not invited]Behaviour of fathead minnow; infected with brain-encysting parasite2005
- 脳内吸虫に感染したFathead minnowの行動 [Not invited]白樫正; C. P. Goater2005
- 日本に侵入した単生類寄生虫によるヒラメ天然資源への影響 [Not invited]白樫正第20回生態学・疫学談話会in第74回日本寄生虫学会大会ワークショップ 2005 米子コンベンションセンター,鳥取県米子市
- 低水温下でのNeoheterobothrium hirameの着定と発育 [Not invited]白樫正; 堤信幸; 良永知義; 岡雅一; 小川和夫平成16年度日本魚病学会大会 2004 函館国際ホテル,北海道函館市
- Effects of Neoheterobothrium hirame on predation of olive flounder, Paralichthys olivaceus [Not invited]S. Shirakashi; K. Teruya; K. Ogawa79th Annual Meeting of the American Society of Parasitologists 2004 DoubleTree Hotel Philadelphia, Pennsylvania, USA
- Effects of Neoheterobothrium hirame on predation and viral hemorrhagic septicaemia infection of olive flounder, Paralichthys olivaceus [Not invited]S. Shirakashi; K. Mori; T. Sugaya; K. Ogawa6th International Symposium on Fish Parasitology 2003 The University of the Free State, Bloemfontein, South Africa
- Intensity dependent alteration of minnow behaviour by a brain encysting trematode [Not invited]S. Shirakashi; C. P. GoaterThe 10th International Congress of Parasitology 2002 The Convention and Exhibition Centre, Vancouver B.C. Canada
- Behaviour of trematode-infected fathead minnows: a test of the parasite-manipulation hypothesis [Not invited]S. Shirakashi; C. P. Goater76th Annual Meeting of the American Society of Parasitologists 2001 The Sheraton Old Town Hotel, Albuquerque, New Mexico, USA
- Infection dynamics of Polymorphus paradoxus (Acanthocephala) in Gammarus lacustris collected from a prairie slough [Not invited]S. ShirakashiAnnual Meeting of the Canadian Society of Zoologists 1998 Okanagan University College, Kelowna, British Columbia. Canada.
Affiliated academic society
Research Themes
- 日本学術振興会:科学研究費助成事業Date (from‐to) : 2021/04 -2024/03Author : 小川 和夫; 白樫 正長崎県産の天然ブリからブリ筋肉線虫Philometroides seriolaeの雌成虫を採集し、そのふ化幼生(第1期幼生)を子宮内から得ることができた。和歌山県白浜町で甲殻類(カイアシ類3種、端脚類2種、十脚類1種)を採集した。これらの甲殻類を小型プラスチック容器内に収容し、P. seriolae雌成虫の子宮内からふ化幼生を取り出して暴露した。幼生を投与直後は実体顕微鏡下で観察して摂食の有無を確認した。その後20℃と25℃で維持して甲殻類体内に幼虫がいるかを解剖、もしくは麻酔をかけて顕微鏡下で確認し、代理宿主としての適性を調べた。その結果、端脚類と十脚類(スジエビの仲間)は幼生を摂食したが、体腔内に虫体は確認できなかった。カイアシ類については、MiraciidaeとTisbiidaeカイアシ類は幼生摂食後、体内に幼虫を確認したが、長期間の維持ができなかった。一方、シオダマリミジンコ(立正大学の岩崎 望先生同定;以下、ミジンコ)は積極的にふ化幼生を摂食し、曝露1時間後には血体腔体内に動く幼虫を確認した。ミジンコ内に最多で3個体の幼虫が確認され、寄生率は最高100%に達した。さらに感染ミジンコの一部を1ヶ月以上生存させることに成功した。ミジンコ内の幼生に脱皮殻を認めたことから、幼生は2期または3期に成長したことも確認された。以上のことから、シオダマリミジンコを代理宿主とする実験系がほぼ確立された。 ブリ筋肉線虫は宿主魚の商品価値を喪失させ、水産業上問題となる。中間宿主が不明であるだけでなく、雄虫も未発見であった。長崎県産の大型天然ブリを2021年4月~9月に計30尾を解剖した。雌成虫をブリ体側筋から取り出す際、寄生部位の洗浄液を検鏡し、雄虫を探索した。その結果、雌成虫140虫を採集したが、同所から2虫の雄成虫を回収することができた。
- Japan Society for the Promotion of Science:Grants-in-Aid for Scientific ResearchDate (from‐to) : 2021/04 -2024/03Author : 横山 博; 柳田 哲矢; 白樫 正滋賀県の養殖ニジマスで見られた新しい微胞子虫症について、皮下体側筋に赤斑を呈する症状が特徴的であること、患部から微胞子虫の胞子が検出され、顕微鏡観察と遺伝子解析の結果、武田微胞子虫Kabatana takedaiに近縁であるものの別種であることがわかった。さらに琵琶湖で捕獲されるスジエビを未感染ニジマスに経口投与すると症状が再現されたため、ニジマスおよびビワマスに対して実験的に投与する感染実験を行った結果、いずれも本症が再現され、感染魚の死亡もみられた。なお、ニジマスとビワマスでは死亡率に差異がみられたものの、スジエビの投与量が異なっていた可能性もあり、そのまま感受性が違うと結論付けられなかった。一方、冷凍エビの投与では感染がみられなかった。以上の結果は、琵琶湖産スジエビを介して本微胞子虫がマス類に感染すること、また今回の微胞子虫は新規の疾病であることが示された。これらの成果は、日本魚病学会および日本寄生虫学会で口頭またはポスターで発表され、さらに学術雑誌「魚病研究」においても、"A new microsporidian disease of rainbow trout Oncorhynchus mykiss farmed in Shiga prefecture, Japan and possible involvement of common prawn Palaemon paucidens for transmission of the pathogen" by Yamamoto et al. Fish Pathol., 56(3), 130-139, 2021.という内容で、論文発表された。また、現在、本微胞子虫の新種記載論文についても作成し、海外の学術雑誌に投稿中である。
- Japan Society for the Promotion of Science:Grants-in-Aid for Scientific ResearchDate (from‐to) : 2019/04 -2024/03Author : 良永 知義; 伊藤 直樹; 白樫 正; 渡邊 勇歩研究課題の4つの研究課題(I. 海産白点虫(以下、白点虫)の生態学的特性に基づく発生予測技術の検討、Ⅱ.化学療法剤の探索と有効性・安全性の検討、Ⅲ. 寄生関連タンパク分解酵素を抗原としたワクチンの検討、IV. 新たなin vitro培養法の開発)それぞれについての成果は以下のとおりである。 I. 令和2年度に開発した新たなプライマーとブローブを用いて、植物プランクトンや自由生活性繊毛を混入させた海水中での白点虫セロントの検出を行い、これらの夾雑物の影響が低いことが明らかとなった。また、白点虫病が発生している水槽から採取した海水中のセロントの定量を試みるとともに、蛍光染色による顕微鏡観察で計数したセロント数を経時的に比較したところ、おおむね似た値を示したものの、かなり異なる時間帯もあり、その原因を明らかにしたうえで、改良を加えることが必要となった。シスト期の白点虫(トモント)への12時間の光照射だけ、また、1 lxという極めて低い照度の光照射だけで、トモントからのセロントの放出の概日リズムが形成されることが明らかとなった。 Ⅱ. in vitroで抗白点虫作用が確認されたイオノフォアの効果を、マダイを用いてin vitroでも確認することができた。さらに、比較のために行った実験では、イオノフォアのヒラメの病原せん毛虫Miamiensis avidusに対する抗虫効果がin vitroとin vivoで確認された。 IV.セロントにアポトーシス細胞を与えても、ほとんど取り込まなかった。そこで、改めて、寄生期のトロホントにおける宿主細胞の取り込みについて検討したところ、宿主細胞を大量に取り込むのは宿主に侵入して48時間以降であることが明らかになった。この観察から、アポトーシス細胞の投与時期について再検討が必要と考えている。 III. ワクチンについては令和3年度は研究をおこなわなかった。
- Japan Society for the Promotion of Science:Grants-in-Aid for Scientific ResearchDate (from‐to) : 2017/04 -2020/03Author : Ogawa KazuoYear-round monthly surveys of the intermediate host polychaetes proliferating on the net cages of tuna cages revealed that polychaetes became infected in summer, while in winter they grew in numbers but no infection occurred. Unexpectedly, removal of polychaetes on the net cages resulted in drastic decrease in the infection of the intermediate host. This suggests that eradication of polychaetes around the culture systems will be an effective control measure of the blood fluke infection of net cage cultured bluefin tuna. We succeeded in in vitro maintenance of infected polychaetes by injecting sporocysts from naturally infected polychaetes into uninfected ones. This has enabled to maintain developmental stages of the blood fluke and to observe its development and proliferation in the intermediate host.
- 日本学術振興会:科学研究費助成事業Date (from‐to) : 2014/04 -2017/03Author : 白樫 正; SHIN SANG PHIL; SHIN Sang Phil粘液胞子虫の一種であるクドアは様々な海産魚に寄生し、魚体の変形や魚肉の変質を引き起こすため、水産業上の重大な問題となっている。また近年ではクドアがヒトの食中毒原因体で有ることが判明し、公衆衛生上も大きな問題となっている。本研究では養殖魚におけるクドアの防除法開発を最終目的として、それに繋がるクドアの生物学的知見を得ると共に、陸上養殖施設で即時利用可能な防除法を確立した。当初予定してたワクチン開発に繋がるプロテアーゼ解析については、期間内の感染体特定が困難であることが分かったため、研究内容を一部変更した。 クドア属粘液胞子虫の分子系統解析を実施し、パナマ産サワラの筋肉中から得た新種クドアの記載(Kudoa rayformis)含め、学術論文に纏めた。これにより、現在国内外で問題となっているクドアについて包括的に情報を整理し、今後の研究課題の方向性を決定することができた。さらに、国内で食中毒原因体として大きな問題となっているヒラメのナナホシクドアについて、同じくヒラメに寄生する複数のクドアと区別する簡便かつ正確な診断法としてマルチプレックスPCRを確立した。同時に、国内養殖ヒラメに寄生するクドア種リストを更新し、学術論文とした。 当初の予定通り、ヒラマサの脳に寄生するK. yasunagaiの魚体内感染動態を調べ、感染初期には消化管で当該種の遺伝子が多く検出できることを確かめた。これにより、侵入門戸が消化管であることが示され、学術論文としてまとめた。 研究の最終目的であるクドア防除法としては、飼育水を15 mJ/ cm2程度の比較的弱い紫外線殺処理することで、寄生を完全に抑えることを突き止めた。これにより、少なくとも陸上養殖施設でのクドア防除法は確立したと言える。 これらの成果は計4報の学術論文としてまとめた。
- Japan Society for the Promotion of Science:Grants-in-Aid for Scientific ResearchDate (from‐to) : 2013/04 -2016/03Author : SHIRAKASHI Sho; OGAWA Kazuo; TSUDA YuichiSkin fluke has been a chronic problem in aquaculture. The present study aims to understand the biology and ecology of Neobenedenia girellae and to develop practical methods to prevent infection in fish farms. Larval fluke are positively phototactic and the infection took place during mid-day near the water surface. Shading of culture cage successfully reduced the infection. An adult fluke laid over 700 eggs per day and the eggs accumulated on the culture cages at the maximum rate of over ten million eggs/day. Large proportions of eggs were attached on the upper part of the cages. Using these newly obtained information, we have proposed effective culture techniques to remove eggs from cage and to reduce infection in fish farms.
- Japan Society for the Promotion of Science:Grants-in-Aid for Scientific ResearchDate (from‐to) : 2013/04 -2016/03Author : Ogawa Kazuo; YOKOYAMA HIROSHI; SHIRAKASHI SHO; HONRYO TOMOKIThree species of blood flukes of the genus Cardicola were identified from farmed Pacific bluefin tuna (PBT). Their intermediate hosts, in which the three blood flukes use different terebellid polychaetes, were determined and their developmental stages were described. All the life cycles of the blood flukes infecting PBT were determined, which are completed within PBT farms. Nicolea gracilibranchis, the intermediatae host of Cardicola orientalis, was most abundant in water depth of 0-4 m, and showed highest prevalence of infection in July. It is estimated that an infected N. gracilibranchis can release up to 1 million cercariae. As for Kudoa infection, K. neothunni and a new species, K. hexapunctata were found in the skeletal muscle. Infection started soon after PBT seeds were transferred from indoor tanks to sea cages. In experiments using Seriola lalandi seeds and Kudoa yasunagai, infection occurred in fish using filtered water, but was prevented using UV radiated water at 15mJ/cm2.
- Japan Society for the Promotion of Science:Grants-in-Aid for Scientific ResearchDate (from‐to) : 2012/04 -2015/03Author : YOKOYAMA Hiroshi; SHIRAKASHI ShoFood poisoning caused by Kudoa septempunctata, a myxosporean infecting the muscle of olive flounder Paralichthys olivaceus, has been a problem in Japan. Recently, other Kudoa spp. has been also suspected to be aetiological agents of food poisoning in humans. Prevalence of infection with Kudoa iwatai was relatively high in yellowfin seabream Acanthopagrus latus, whereas maturity of cysts and viability of spores were high in Japanese seabass Lateolabrax japonicus. Toxicity of K. iwatai could not be demonstrated in Caco-2 cell monolayer permeability assay. On the other hand, toxicity of Kudoa hexapunctata, a newly described species from juvenile Pacific bluefin tuna Thunnus orientalis, to Caco-2 cells were shown. Risk assessment of K. hexapunctata was made based on some information of spore dose with toxic effects on Caco-2 cells and treatment conditions inactivating the spores.
- Japan Society for the Promotion of Science:Grants-in-Aid for Scientific ResearchDate (from‐to) : 2010 -2012Author : OGAWA Kazuo; YOSHINAGA Tomoyoshi; SAWADA Yoshifumi; ISIMARU Katsuya; SHIRAKASHI ShoFirstly, a second blood fluke species from Pacific bluefin tuna was found from the heart ventricle and described as Cardicola opisthorchis n. sp. Secondly, new methods were developed to distinguish eggs of C. orientalis from those of C. opisthorchis morphologically, and to count the number of eggs in the gills. Thirdly, infection cycle was partly elucidated. Namely, both species of blood flukes were found in juvenile tuna 45 days after transfer to outside net cages; one week later, flukes were matured and laid eggs after one more week. Fourthly, C. opisthorchis was eradicated from tuna with oral administration of praziquantel (PZQ) at 7.5 mg/kg fish body weight or more for 3 consecutive days. Reinfection was confirmed 1 month after medication. PZQ concentration in tuna decreased to the undetectable level(0.02 μg/L)24 h after administration. Lastly, SEM observation of the two species of blood flukes shows swelling and contraction of the tegument and formation of many minute furrowed ridges in C. opisthorchis, while in C. orientalis, many minute holes were characteristically formed on the tegument.
- 日本学術振興会:科学研究費助成事業Date (from‐to) : 2003 -2004Author : 白樫 正ヒラメの寄生虫Neoheterobothrium hirameが天然ヒラメ稚魚の生存に及ぼす影響を調べるため、実験的に感染させたヒラメ稚魚の行動、捕食率、飢餓耐性、ウイルス病(VHSV)に対する感受性等を調べた。 行動実験では感染ヒラメ稚魚で潜砂、遊泳能力の著しい低下がみられ、その活動パターン、摂餌行動が非感染対象区と異なることが分かった。また、捕食実験において、感染ヒラメ稚魚、非感染ヒラメ稚魚、そして捕食者となる大型ヒラメを96時間同居飼育した結果、感染ヒラメ稚魚はより捕食を受けやすいことが明らかになった。さらに、ヒラメ稚魚に寄生虫N.hirameとウイルス性出血性敗血症ウイルス(VHSV)による混合感染実験を行った結果、両者の病原体に感染した魚ではいずれかの病原体に単独感染した魚より著しく高い死亡がみられ、N.hirameによってヒラメのウイルス病に対する感受性が増すことが考えられた。 さらに、2年間におよぶフィールド調査により、ヒラメ漁獲の現象が顕著な海域では感染ヒラメ1尾あたりのN.hirame虫数(寄生虫)が漁獲の安定している海域より著しく多いことが明らかになり、N.hirameとヒラメ資源減少の因果関係が示唆された。このフィールド調査の結果を基に行った実験では、10℃以下の低水温下ではN.hirameの感染力や発育が著しく低下することが分かり、海域間で見られたN.hirame寄生数の差はそれぞれの海域の温度差によるものであると考えられた。 これらの研究で、近年日本沿岸で深刻な問題となっているヒラメ資源の減少に対する新種の移入寄生虫、N.hirameの関与を支持する重要な知見が得られた。