Kanmani Chandra Rajan, Vengatesen Thiyagarajan, Mohamed Madhar Fazil Sheik Oli, Muthusamy Ayyadurai, Mason N Dean
{"title":"Oyster larval biomineralisation - insights from electron backscatter diffraction.","authors":"Kanmani Chandra Rajan, Vengatesen Thiyagarajan, Mohamed Madhar Fazil Sheik Oli, Muthusamy Ayyadurai, Mason N Dean","doi":"10.1039/d5fd00038f","DOIUrl":null,"url":null,"abstract":"<p><p>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 (<i>Pinctada</i> 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 (<i>Magallana hongkongensis</i>). 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 <i>c</i>-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.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":""},"PeriodicalIF":3.1000,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Faraday Discussions","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1039/d5fd00038f","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
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 (Pinctada 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 (Magallana hongkongensis). 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 c-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.
生物矿化的开始对有壳生物的生态至关重要,例如在动物特别脆弱的生命早期阶段提供保护。在牡蛎中,涉及早期贝壳沉积的过程仍然存在争议——是无定形碳酸钙(ACC)最初沉积并转化为文石,还是文石直接沉积——主要是由于研究最年轻的年龄类别和有限的模式物种多样性的挑战。由于珍珠形成的商业利益,人们主要研究珍珠贝(Pinctada spp.)的早期幼虫壳沉积。然而,可食用牡蛎的生物矿化仍然相对未被探索,尽管在定居后生存具有重要的商业意义。在这项研究中,我们提供了一个相对未经研究的,生态和商业上重要的可食用物种,香港牡蛎(Magallana hongkongensis)的壳晶体学的比较分析。我们专注于三个重要的生命阶段- d -幼虫(受精后3天),pediveliger(受精后14天)和贝(沉降后3个月)-在这三个阶段,壳的厚度急剧增加并改变了其微观结构。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)幼虫的壳完全由文石晶体组成,没有检测到ACC的痕迹,而贝的壳呈钙质;(2)相对于斑片,幼虫的壳显示出更强的晶体c轴垂直于壳表面的排列,这表明在生命早期可能对矿化过程有更严格的控制;(3)随着牡蛎的成熟,壳粒面积增加,可能与文石向方解石的转变有关,但也与幼虫壳的成熟有关。这些关于牡蛎壳结构超微结构变化的定量数据促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提供了基础。