Host-parasite relationship between chytrid and harmful dinoflagellates in sediment of the marine environment

• Project/Area Number: 24580289
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: General fisheries
• Research Institution: Fisheries Research Agency
• Principal Investigator: YAMAGUCHI Mineo 独立行政法人水産総合研究センター, 瀬戸内海区水産研究所, 主幹研究員 (00371956)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Project Status: Completed (Fiscal Year 2014)
• Budget Amount: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000); Fiscal Year 2014: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2013: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2012: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
• Keywords: 菌類 / ツボカビ / 有毒プランクトン / 寄生 / 渦鞭毛藻 / 海洋 / 海底堆積物 / シスト

Outline of Final Research Achievements

During the germination experiments of the cysts by incubating sediment suspensions, we have found epibiotic and endobiotic fungal parasites on the germinated cells and/or the cysts of marine dinoflagellates Alexandrium tamarense and Scrippsiella trochoidea. In the present study we characterized and identified these fungi by microscopic observation and rDNA sequence analysis. Results showed that the epibiotc fungi belonged to the Rhizophydium clade or Lobulomycetales, Chytridiomycota. We also succeeded in obtaining culturable strain of Rhizophydium from Ofunato Bay for the first time. Although taxonomic position of the endobiotic fungus yet to be identified, it belonged to neither “core chytrid clade” nor Oomycota. Our finding indicates that a variety of fungal parasites can have significant impacts on marine dinoflagellates and parasitism needs to be considered in understanding of their bloom dynamics.

Research Products

• [Presentation] 有毒渦鞭毛藻Alexandriumに寄生する真核微生物-Ⅱ―シスト寄生菌および培養可能ツボカビの形態・分子系統学的特徴― (2015)
  • Author(s): 山口峰生・坂本節子・木村圭・加賀新之助・加賀克昌・内記公明
  • Organizer: 平成27年度日本水産学会春季大会
  • Place of Presentation: 東京海洋大学
  • Year and Date: 2015-03-28
• [Presentation] HABとパラサイト (2014)
  • Author(s): 山口峰生
  • Organizer: 漁場環境保全関係研究開発推進会議赤潮・貝毒部会
  • Place of Presentation: 広島国際会議場
  • Year and Date: 2014-12-05
• [Presentation] Morphological and molecular characterization of eukaryotic parasitoids on toxic marine dinoflagellate Alexandrium tamarense (2014)
  • Author(s): Mineo Yamaguchi, Kei Kimura, Setsuko Sakamoto, Shinnosuke Kaga, Yoshimasa Kaga, Kimiaki Naiki
  • Organizer: The 16th International Conference on Harmful Algae
  • Place of Presentation: Michael Fowler Centre, Wellington, New Zealand
  • Year and Date: 2014-10-27
• [Presentation] 海産渦鞭毛藻に寄生する真核微生物の多様性 (2014)
  • Author(s): 山口峰生・木村 圭・坂本節子
  • Organizer: 日本プランクトン学会・日本ベントス学会合同大会
  • Place of Presentation: 広島大学
  • Year and Date: 2014-09-06
• [Presentation] 海産渦鞭毛藻に寄生するツボカビの形態学的特徴と分子系統解析
  • Author(s): 山口峰生・坂本節子
  • Organizer: 2013年日本ベントス学会・日本プランクトン学会合同大会
  • Place of Presentation: 東北大学
• [Presentation] 岩手県大船渡湾から分離された海産ツボカビRhizophydiumについて
  • Author(s): 山口峰生・坂本節子
  • Organizer: 日本菌学会第58回大会
  • Place of Presentation: サイエンスヒルズこまつ