Chandra Rajan Kanmani, Thiyagarajan Vengatesen, Sheik Oli Mohamed Madhar Fazil, Ayyadurai Muthusamy, Dean Mason N
Department of Infectious Diseases and Public Health, City University of Hong Kong, Hong Kong SAR.
Centre for Nature Inspired Engineering, City University of Hong Kong, Hong Kong SAR.
Faraday Discuss. 2025 Sep 11;261(0):380-395. doi: 10.1039/d5fd00038f.
The initiation of biomineralisation is crucial to the ecology of shelled organisms, for instance providing protection during early life stages when animals are particularly vulnerable. In oysters, the processes involved in early shell deposition remain debated-whether amorphous calcium carbonate (ACC) is deposited initially and transforms into aragonite, or aragonite is directly deposited-largely due to challenges examining the youngest age classes and the limited diversity of model species. Early larval shell deposition has primarily been studied in pearl oysters ( spp.) due to commercial interests in pearl formation. Edible oyster biomineralisation, however, remains relatively unexplored, despite the commercial importance of post-settlement survival. In this study, we provide a comparative analysis of shell crystallography of a relatively unexamined, ecologically and commercially important edible species, the Hong Kong oyster (). We focus on three important life stages-D-larvae (3 days post fertilisation), pediveliger (14 days post fertilisation) and spat (three months post settlement)-over which the shell increases drastically in thickness and alters its microstructure. Employing Scanning Electron Microscopy-based Electron BackScatter Diffraction (SEM-EBSD), we show: (1) larval shells are made entirely of aragonite crystals with no traces of ACC detected, whereas spat exhibit calcitic shells; (2) relative to spats, larval shells show a stronger alignment of their crystal -axes perpendicular to the shell surface, suggesting perhaps a tighter control of mineralisation processes in early life stages; (3) shell grain area increases as the oyster matures, likely linked to the aragonite-to-calcite shift, but also maturation of the larval shell. These quantitative data on ultra- and microstructural changes in oyster shell architecture advance our understanding of early biomineralisation in edible oysters; by elucidating the mechanisms of crystal deposition and organization, we provide a foundation for designing novel materials inspired by natural biomineralisation processes.
生物矿化的起始对于有壳生物的生态学至关重要，例如在动物特别脆弱的早期生命阶段提供保护。在牡蛎中，早期贝壳沉积所涉及的过程仍存在争议——是最初沉积无定形碳酸钙（ACC）并转化为文石，还是直接沉积文石——这主要是由于研究最年幼年龄组存在挑战以及模型物种的多样性有限。由于对珍珠形成的商业兴趣，早期幼虫贝壳沉积主要在珍珠牡蛎（ 属）中进行了研究。然而，尽管定居后存活具有商业重要性，但食用牡蛎的生物矿化仍相对未被探索。在本研究中，我们对一种相对未被研究、具有生态和商业重要性的食用物种——香港牡蛎（ ）的贝壳晶体学进行了比较分析。我们关注三个重要的生命阶段——D形幼虫（受精后3天）、壳顶幼虫（受精后14天）和稚贝（定居后三个月）——在此期间贝壳厚度急剧增加并改变其微观结构。利用基于扫描电子显微镜的电子背散射衍射（SEM-EBSD），我们发现：（1）幼虫贝壳完全由文石晶体构成，未检测到ACC痕迹，而稚贝壳为方解石质；（2）相对于稚贝，幼虫贝壳的晶体轴在垂直于贝壳表面方向上排列更强，这可能表明早期生命阶段矿化过程受到更严格的控制；（3）随着牡蛎成熟，贝壳晶粒面积增加，这可能与文石向方解石的转变有关，也与幼虫贝壳的成熟有关。这些关于牡蛎贝壳结构超微和微观结构变化的定量数据推进了我们对食用牡蛎早期生物矿化的理解；通过阐明晶体沉积和组织的机制，我们为设计受自然生物矿化过程启发的新型材料奠定了基础。
