Athanasiadou, Dimitra, Wenge, Jiang, Reznikov, Natalie et al. (6 more authors) (2020) Nanostructure of Mouse Otoconia. JOURNAL OF STRUCTURAL BIOLOGY. pp. 1-11. ISSN 1047-8477
Abstract
Mammalian otoconia of the inner ear vestibular apparatus are calcium carbonate-containing mineralized structures critical in maintaining balance and detecting linear acceleration. The mineral phase of otoconia is calcite, which coherently diffracts X-rays much like a single-crystal. Otoconia contain osteopontin (OPN), a mineral-binding protein influencing mineralization processes in bones, teeth and avian eggshells, for example, and in pathologic mineral deposits. Here we describe mineral nanostructure and the distribution of OPN in mouse otoconia. Scanning electron microscopy and atomic force microscopy of intact and cleaved mouse otoconia revealed an internal nanostructure (∼50 nm). Transmission electron microscopy and electron tomography of focused ion beam-prepared sections of otoconia confirmed this mineral nanostructure, and identified even smaller (∼10 nm) nanograin dimensions. X-ray diffraction of mature otoconia (8-day-old mice) showed crystallite size in a similar range (73 nm and smaller). Raman and X-ray absorption spectroscopy – both methods being sensitive to the detection of crystalline and amorphous forms in the sample – showed no evidence of amorphous calcium carbonate in these mature otoconia. Scanning and transmission electron microscopy combined with colloidal-gold immunolabeling for OPN revealed that this protein was located at the surface of the otoconia, correlating with a site where surface nanostructure was observed. OPN addition to calcite growing in vitro produced similar surface nanostructure. Finally, these findings provide details on the composition and nanostructure of mammalian otoconia, and suggest that while OPN may influence surface rounding and surface nanostructure in otoconia, other incorporated proteins (also possibly including OPN) likely participate in creating internal nanostructure.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 Elsevier Inc. All rights reserved. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Physics (York) |
Funding Information: | Funder Grant number EPSRC EP/I001514/1 |
Depositing User: | Pure (York) |
Date Deposited: | 09 Mar 2020 16:50 |
Last Modified: | 29 Dec 2024 00:11 |
Published Version: | https://doi.org/10.1016/j.jsb.2020.107489 |
Status: | Published online |
Refereed: | Yes |
Identification Number: | 10.1016/j.jsb.2020.107489 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:158236 |