To high-quality pearl production - Research of the effects of immunosuppression on mother pearl before implantation

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K06204
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: Mie University
• Principal Investigator: Sano Natsumi 三重大学, 生物資源学研究科, 学術研究員 (50636545)
• Co-Investigator(Kenkyū-buntansha): 古丸 明 三重大学, 生物資源学研究科, 教授 (10293804)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: アコヤガイ / 真珠 / 外套膜 / 殻体基質タンパク質 / 活性酸素分解酵素 / SOD

Outline of Final Research Achievements

In pearl culture, there is a process called "Shitate" in which mother oysters are physiologically controlled by overcrowding before the insertion. The purpose of this study was to provide an index of "Shitate". We compared the gene expression in the mantle of the pearl oyster with and without "Shitate" by RNA-seq and found that "Shitate" causes a decrease in genes related to the formation of prismatic layer (msi31 and Prismarin-14) and an increase in reactive superoxide dismutase(SOD). However, the kinetics of expression of these genes in the pearl sac did not differ significantly between "Shitate” and non-"Shitate”, and there was no association between "Shitate” and improved pearl quality. However, SOD was also found to vary with "Shitate” as an enzyme activity, suggesting that it may be a candidate for an indicator. Furthermore, SOD was also found to be elevated in summer mantle atrophy.

Free Research Field

水産増殖

Academic Significance and Societal Importance of the Research Achievements

挿核前に母貝を過密飼育などで生理的な抑制をする「仕立て」により真珠品質が向上すると考えられているが，その反面，疾病に対する抵抗性が落ちることが知られている。真珠品質を保ちながら抵抗性を低下させ過ぎない仕立ての指標を探索することを目的として，真珠形成に用いられる真珠袋を形成する外套膜組織でのいくつかの遺伝子の顕著な変動を明らかにした。その中でも，組織を採取せず，酵素活性として測定できる活性酸素分解酵素が指標となりうる結果を得た。また，この酵素が2019年から全国の真珠養殖場で問題となっている夏季外套膜萎縮症で上昇することを明らかにし，今後，この病気の問題解決に繋がる結果を得ることが出来た。