Tsujimoto, Megumu

写真a

Affiliation

Graduate School of Media and Governance (Shonan Fujisawa)

Position

Project Senior Assistant Professor (Non-tenured)/Project Assistant Professor (Non-tenured)/Project Lecturer (Non-tenured)
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Papers 【 Display / hide 】

  • Molecular identity of the Antarctic heteronemertean Parborlasia corrugata (Nemertea: Pilidiophora) from Lützow-Holm Bay

    Hookabe N., Watanabe K., Tsujimoto M., Kajihara H.

    Polar Science (Polar Science)  25 2020.09

    ISSN  18739652

    　View Summary

    © 2020 Elsevier B.V. and NIPR The Antarctic heteronemertean Parborlasia corrugata (McIntosh, 1876) (originally Lineus corrugatus) shows a circumpolar distribution in the Southern Ocean, putatively with high dispersal capacity of the planktonic larva. From the eastern coast of Lützow-Holm Bay near Syowa Station (69°00′S, 39°35′E), several records of heteronemerteans have been made under the name of Lineus corrugatus. However, they have never been explicitly identified by molecular data. In the present study, we determined a partial sequence of the mitochondrial cytochrome c oxidase subunit I (COI) gene for 11 specimens of P. corrugata collected from depths of 17–27 m under sea ice near Syowa Station. A haplotype-network analysis along with other COI sequences from 66 individuals collected at different places in the Antarctic and sub-Antarctic islands, available at public databases, resulted in that all the 11 specimens from Lützow-Holm Bay possessed either of two major haplotypes detected in previous studies. It reflects the effective dispersal of the species between the localities including Lützow-Holm Bay.

  • Marine tardigrades from Lützow-Holm Bay, East Antarctica with the description of a new species

    Fujimoto S., Suzuki A.C., Ito M., Tamura T., Tsujimoto M.

    Polar Biology (Polar Biology)  43 ( 6 ) 679 - 693 2020.06

    ISSN  07224060

    　View Summary

    © 2020, Springer-Verlag GmbH Germany, part of Springer Nature. Marine tardigrades in the Antarctic and sub-Antarctic regions are poorly understood. During the 59th Japan Antarctic Research Expedition, a sediment sample was collected from Lützow-Holm Bay, East Antarctica. The sediment sample yielded three species of marine tardigrades belonging to the family Styraconyxidae Kristensen & Renaud-Mornant, 1983: Angursa antarctica Villora-Moreno, 1998, Styraconyx cf. qivitoq Kristensen & Higgins, 1984, and S. takeshii sp. nov. The new species resembles S. nanoqsunguak Kristensen & Higgins, 1984 by the overall morphology, but the new species has thick seminal receptacle ducts that do not terminate in typical, swelled vesicles, in contrast to S. nanoqsunguak’s narrow seminal receptacle ducts that terminate in small vesicles. The presence of the undivided mouth papilla and the larger body further differentiates the new species from S. nanoqsunguak. We also report a young adult female with a gonopore, but lacking seminal receptacles in the new species. As well as morphological information, we provided the sequences of the new species’ nuclear 28S rRNA and mitochondrial cytochrome c oxidase subunit I fragments. Using the former molecular data, phylogenetic analyses of Styraconyxidae were conducted and polyphyly of Styraconyx was suggested. The biogeography of marine tardigrades in the Antarctic and sub-Antarctic regions are also discussed.

  • Reproductive performance of the Antarctic tardigrades, Acutuncus antarcticus (Eutardigrada: Hypsibiidae), revived after being frozen for over 30 years and of their offspring

    Tsujimoto M., Kagoshima H., Kanda H., Watanabe K., Imura S.

    Zoological Journal of the Linnean Society (Zoological Journal of the Linnean Society)  188 ( 3 ) 839 - 847 2020

    ISSN  00244082

    　View Summary

    © Zoological Journal of the Linnean Society 2019. Studies on the long-term survival of animals often focus on the specific instance of survival of animals only, and descriptions of subsequent reproduction are generally not reported. In this study, we recorded the reproductive performance of the first-generation offspring of the resuscitated individual (SB-1) and the hatchling of the resuscitated egg (SB-3) of the Antarctic tardigrade, Acutuncus antarcticus, after being frozen for 30.5 years. By providing further detailed description of the reproduction of SB-1 and SB-3 after revival, and then comparing the reproductive performance with that of their first-generation offspring, the possible indications of the damage accrued during the long-term preservation in SB-1 and SB-3 were more specifically detected. Additionally, the DNA analysis revealed two distinctively different mitochondrial genetic sequences of A. antarcticus between the SB strains and the LSW strain. The observed differences in some of the reproductive parameters between the two genetic types suggested a possible relationship between the life-history traits and genetic type in the species A. antarcticus. Further experiments using the SB-1 and SB-3 strains reared for a long period to exclude the instant effect of preservation are expected to improve our understanding of the mechanisms underlying the long-term survival of animals.

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • 南極大陸を取り巻く海産微小底生動物の分化過程と進化史の解明

    2020.04
    -
    2022.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research on Innovative Areas, Principal investigator

  • 極限環境を生き抜く南極クマムシの生存戦略としての耐性機構の解明

    2018.04
    -
    2020.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Early-Career Scientists , Principal investigator

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Courses Taught 【 Display / hide 】

  • ACADEMIC PROJECT

    2023

  • SEMINAR B

    2023

  • GRADUATION PROJECT 2

    2023

  • GRADUATION PROJECT 1

    2023

  • ENVIRONMENTAL ISSUES IN POLAR REGIONS

    2023

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