【公開日:2025.06.10】【最終更新日:2025.05.20】
課題データ / Project Data
課題番号 / Project Issue Number
24UT0204
利用課題名 / Title
Crystal Puzzle: Temperature- and pH-dependent microstructural plasticity in the Pinctada fucata nacre
利用した実施機関 / Support Institute
東京大学 / Tokyo Univ.
機関外・機関内の利用 / External or Internal Use
内部利用(ARIM事業参画者以外)/Internal Use (by non ARIM members)
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】(主 / Main)計測・分析/Advanced Characterization(副 / Sub)-
【重要技術領域 / Important Technology Area】(主 / Main)次世代バイオマテリアル/Next-generation biomaterials(副 / Sub)-
キーワード / Keywords
nacre, behavior in response to changes in the environment,電子顕微鏡/ Electronic microscope,電子回折/ Electron diffraction
利用者と利用形態 / User and Support Type
利用者名(課題申請者)/ User Name (Project Applicant)
Siu Sienna
所属名 / Affiliation
東京大学大学院理学系研科 地球惑星科学専攻
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
利用形態 / Support Type
(主 / Main)機器利用/Equipment Utilization(副 / Sub)-
利用した主な設備 / Equipment Used in This Project
報告書データ / Report
概要(目的・用途・実施内容)/ Abstract (Aim, Use Applications and Contents)
Nacre, or mother-of-pearl, is a biomineralized material renowned for its exceptional mechanical properties, arising from its intricate microstructure of aragonite tablets interwoven with an organic matrix. While the physical and biochemical processes underlying nacre formation are relatively well-studied, the extent to which nacre exhibits phenotypic plasticity in response to environmental changes remains less understood. This thesis investigates the effects of temperature and pH—two critical environmental variables associated with climate change—on the microstructural and molecular characteristics of nacre in Pinctada fucata. Using a combination of experimental rearing under controlled temperature (20°C and 28°C) and pH (7.8 and 8.2) conditions, electron microscopy, and transcriptomic analyses, I explored how environmental factors influence nacre tablet thickness, organic layer spacing, and crystallographic orientation. The results demonstrate a positive correlation between temperature and both nacre tablet and organic layer thickness, with no clear pattern emerging for the effects of pH on tablet thickness. However, lower pH conditions were associated with greater variability in tablet orientation, particularly at higher temperatures, suggesting that acidification stress disrupts nacre tablet organization. Gene expression data revealed distinct expression profiles, but no consistent patterns of upregulation or downregulation of individual genes across experimental conditions. This suggests a dynamic regulatory system that likely involves feedback mechanisms to maintain stable mineralizing environments.
These findings support the hypothesis that nacre biomineralization involves a combination of biological and physicochemical mechanisms, where organisms manipulate boundary conditions to achieve different outcomes within a robust system. The flexibility of nacre tablet traits under varying environmental conditions is at least partially modulated by biological processes, which renders these traits as cases of phenotypic plasticity.
By integrating phenotypic and transcriptomic data, this study contributes to the understanding of nacre biomineralization as a dynamic and biologically mediated process. These findings have broader implications for studying the evolutionary and ecological significance of phenotypic plasticity in biomineralization, emphasizing the importance of biological mediation in shaping traits often perceived as purely physicochemical.
実験 / Experimental
After being observed under SEM, four samples from each experimental condition were repurposed for electron backscattering diffraction analysis(JSM-7000F). Each sample was repolished using diamond paste and colloidal silica, then coated with 1 nm osmium for analysis.
結果と考察 / Results and Discussion
The data indicate distinct orientation patterns across different temperature and pH conditions. In samples reared at 28°C/pH 8.2 and 20°C/pH 8.2, the nacre tablets display relatively narrow angular distributions, suggesting a high degree of crystallographic alignment. However, in conditions of 28°C/pH 7.8, the pole figures reveal a broader angle spread, indicating reduced alignment and greater variability in the crystallographic orientation. This trend is less pronounced but still observable in some of the 20°C/pH 7.8 samples.
図・表・数式 / Figures, Tables and Equations
その他・特記事項(参考文献・謝辞等) / Remarks(References and Acknowledgements)
成果発表・成果利用 / Publication and Patents
論文・プロシーディング(DOIのあるもの) / DOI (Publication and Proceedings)
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
特許 / Patents
特許出願件数 / Number of Patent Applications:0件
特許登録件数 / Number of Registered Patents:0件