The study for the chorionic expansion inducing factor in squid which is essential for the normal development of squids

• Project/Area Number: 15K07578
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Aquatic life science
• Research Institution: Kochi University
• Principal Investigator: ADACHI KOHSUKE 高知大学, 教育研究部自然科学系農学部門, 准教授 (00399114)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000); Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2016: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2015: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
• Keywords: イカ類 / 卵膜膨張 / 輸卵管腺 / 抱卵腺

Outline of Final Research Achievements

After fertilization, the squid ova are released in into egg mass. The diameter is about doubled before hatching. This is called as “chorionic expansion”which is essential for normal development of squid. In previous reports, chorionic expansion is induced by some factors in oviducal gland which is a secretion organ of egg mass component. And it is generally thought that this is caused by increased osmotic pressure of fluid in ova, however, but the details remains unknown.
In this study, we prepared some fractions from oviducal gland and narrowed down the inducing factors to several candidates using ova of Todarodes pacificus. Simultaneously, using Sepioteuthis lessoniana it was suggested that chorionic expansion was induced by the increase of the mineral ion concentration in the ova, and water molecules may be transported on the egg membrane via aquaporin.

Academic Significance and Societal Importance of the Research Achievements

卵膜の膨張は主要なイカ類では普遍的に見られる現象である。また卵塊の分泌組織である輸卵管腺はその重要性に関わらず、生物学的・生化学的機能はほとんど明らかにされてこなかった。本研究によって輸卵管腺の主成分であるムチンを除去した画分を用いた実験により卵膜を膨張させる因子をある程度絞り込むことが出来た。また、同現象は卵内の無機イオン濃度の上昇によって浸透圧が上昇し、アクアポリンを介した水分子の卵膜上の輸送することで引き起こされることがはじめて示唆された。長年不明であったイカ類の卵膜膨張の物理化学的メカニズムの端緒が明らかになったことに本研究の学術的意義がある。

Research Products

• [Journal Article] Structure and properties of the egg mass of the ommastrephid squid Todarodes pacificus. (2017)
  • Author(s): Puneeta、P., Vijai, D., Yamamoto, J., Adachi, K., Kato, Y., Sakurai, Y.
  • Journal Title: PLOS ONE Volume: 12 Issue: 8 Pages: e0182261-e0182261
  • DOI: 10.1371/journal.pone.0182261
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Salt soluble without jelly-like component from the oviducal gland induces chorionic expansion in the ova of the Japanese common squid Todarodes pacificus, (2016)
  • Author(s): Adachi, K., Yabumoto, M., Yoo, H., Morioka, K., Ikeda, Y., Ueta, Y., Sakurai.
  • Journal Title: Invertebrate Reproduction& Development Volume: 60 Issue: 4 Pages: 281-239
  • DOI: 10.1080/07924259.2016.1229234
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Presentation] 生化学者が説明するイカ学 (2016)
  • Author(s): 足立亨介
  • Organizer: 第26回柏島･里海セミナー
  • Place of Presentation: 高知県大月町
  • Year and Date: 2016-02-21
• [Presentation] Salt soluble component from the oviducal gland induces chorionic expansion in the ova of the Japanese common squid Todarodes pacificus (2015)
  • Author(s): Kohsuke Adachi, Mao Yabumoto, Haekyun Yoo, Katsuji Morioka, Yuzuru Ikeda, Yukio Ueta, and Yasunori Sakurai
  • Organizer: CIAC2015
  • Place of Presentation: 函館
  • Year and Date: 2015-11-06
  • Int'l Joint Research
• [Presentation] スルメイカ輸卵管腺抽出物の同種卵膜膨張への効果 (2015)
  • Author(s): 永島宗弥・藪本真央（高知大農）・HAEKYUN YOO（北大院水産）・池田譲（琉球大理）、上田幸男（農林水産総合技術支援セ）、桜井 泰憲（北大院水産）・足立亨介・森岡克司（高知大農）
  • Organizer: ）日本水産学会中国四国支部会
  • Place of Presentation: 香川大学農学部
  • Year and Date: 2015-10-24