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Author Li, Ying Chun ♦ Sato, Hiroshi ♦ Tanaka, Shuhei ♦ Ohnishi, Takahiro ♦ Kamata, Yoichi ♦ Sugita Konishi, Yoshiko
Source SpringerLink
Content type Text
Publisher Springer-Verlag
File Format PDF
Copyright Year ©2013
Language English
Subject Domain (in DDC) Technology ♦ Medicine & health
Subject Keyword Medical Microbiology ♦ Microbiology ♦ Immunology
Abstract Kudoa neothunni is the first described Kudoa species having six shell valves and polar capsules, previously assigned to the genus Hexacapsula Arai and Matsumoto, 1953. Since its genetic analyses remain to be conducted, the present study characterizes the ribosomal RNA gene (rDNA) using two isolates from a yellowfin tuna (Thunnus albacares) with post-harvest myoliquefaction and a northern bluefin tuna (Thunnus thynnus) without tissue degradation. Spores of the two isolates localized in the myofiber of trunk muscles, forming pseudocysts, and showed typical morphology of K. neothunni with six equal-sized shell valves radially arranged in apical view: spores (n = 15) measuring 9.5–11.4 μm in width, 7.3–8.6 μm in suture width, 8.9–10.9 μm in thickness, and 7.3–7.7 μm in length; and polar capsules measuring 3.6–4.1 μm by 1.8–2.3 μm. In lateral view, the spores were pyramidal in shape without apical protrusions. Their 18S and 5.8S rDNA sequences were essentially identical, but variations in the ITS1 (62.4 % similarity across 757-bp length), ITS2 (66.9 % similarity across 599-bp length), and 28S (99.0 % similarity across 2,245-bp length) rDNA regions existed between the two isolates. On phylogenetic trees based on the 18S or 28S rDNA sequence, K. neothunni formed a clade with Kudoa spp. with more than four shell valves and polar capsules, particularly K. grammatorcyni and K. scomberomori. Semiquadrate spores of a kudoid species with four shell valves and polar capsules were detected from minute cysts (0.30–0.75 mm by 0.20–0.40 mm) embedded in the trunk muscle of a chub mackerel (Scomber japonicus) fished in the Sea of Japan. Morphologically, it resembled K. caudata described from a chub mackerel fished in the southeastern Pacific Ocean off Peru; however, it lacked filamentous projections on the shell valves of spores. Additionally, it morphologically resembled K. thunni described from a yellowfin tuna also fished in the Pacific Ocean; spores (n = 30) measuring 8.2–10.5 μm in width, 7.0–8.8 μm in thickness, and 6.1–6.8 μm in length; and polar capsule measuring 2.5–3.4 μm by 1.3–2.0 μm. The similarities of the 18S and 28S rDNA sequences between these two species were 98.5 % and 96.3 %, respectively. Simultaneously, the dimensions of cysts in the trunk muscle formed by K. thunni are clearly larger than those of the present species from a chub mackerel: 1.3–2.0 mm by 1.1–1.4 mm (n = 14) vs. 0.30–0.75 mm by 0.20–0.40 mm (n = 7), respectively. Thus, Kudoa scomberi n. sp. is proposed for this multivalvulid species found in the chub mackerel.
ISSN 09320113
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2013-02-28
Publisher Place Berlin/Heidelberg
e-ISSN 14321955
Journal Parasitology Research
Volume Number 112
Issue Number 5
Page Count 13
Starting Page 1991
Ending Page 2003

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Source: SpringerLink