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Ontogeny of the elemental composition and the biomechanics of radular teeth in the chiton Lepidochitona cinerea

BACKGROUND: The radula, a chitinous membrane with embedded teeth, is one important molluscan autapomorphy. In some taxa (Polyplacophora and Patellogastropoda) one tooth type (the dominant lateral tooth) was studied intensively in the last decades with regard to its mechanical properties, chemical an...

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Autores principales: Krings, Wencke, Brütt, Jan-Ole, Gorb, Stanislav N.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9188181/
https://www.ncbi.nlm.nih.gov/pubmed/35690761
http://dx.doi.org/10.1186/s12983-022-00465-w
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author Krings, Wencke
Brütt, Jan-Ole
Gorb, Stanislav N.
author_facet Krings, Wencke
Brütt, Jan-Ole
Gorb, Stanislav N.
author_sort Krings, Wencke
collection PubMed
description BACKGROUND: The radula, a chitinous membrane with embedded teeth, is one important molluscan autapomorphy. In some taxa (Polyplacophora and Patellogastropoda) one tooth type (the dominant lateral tooth) was studied intensively in the last decades with regard to its mechanical properties, chemical and structural composition, and the relationship between these parameters. As the dominant lateral tooth is probably one of the best studied biological materials, it is surprising, that data on elements and mechanical properties of the other tooth types, present on a chiton radula, is lacking. RESULTS: We provide data on the elemental distribution and mechanical properties (hardness and elasticity, i.e. Young’s modulus) of all teeth from the Polyplacophora Lepidochitona cinerea (Linnaeus, 1767) [Chitonidae: Ischnochitonidae]. The ontogeny of elements, studied by energy-dispersive X-ray spectroscopy, and of the mechanical properties, determined by nanoindentation, was analysed in every individual tooth type. Additionally, we performed breaking stress experiments with teeth under dry and wet condition, highlighting the high influence of the water content on the mechanical behaviour of the radula. We thereby could determine the forces and stresses, teeth can resist, which were previously not studied in representatives of Polyplacophora. Overall, we were able to relate the mineral (iron, calcium) content with the mechanical parameters (hardness and Young’s modulus) and the breaking force and stress in every tooth type. This led to a better understanding of the relationship between structure, material, and function in radular teeth. Further, we aimed at determining the role of calcium for the mechanical behaviour of the teeth: we decalcified radulae by ethylene diamine tetra acetic acid and performed afterwards elemental analyses, breaking stress experiments, and nanoindentation. Among other things, we detected that wet and decalcified radular teeth could resist highest forces, since teeth have a higher range of bending motion leading to a higher capability of teeth to gain mechanical support from the adjacent tooth row. This indicates, that the tooth material is the result of a compromise between failure reduction and the ability to transfer forces onto the ingesta. CONCLUSION: We present novel data on the elemental composition, mechanical properties, and the mechanical behaviour of chiton teeth, which allows conclusions about tooth function. We could also relate the parameters mentioned, which contributes to our understanding on the origins of mechanical property gradients and the processes reducing structural failure in radular teeth. Additionally, we add more evidence, that the elemental composition of radular is probably species-specific and could be used as taxonomic character. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12983-022-00465-w.
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spelling pubmed-91881812022-06-12 Ontogeny of the elemental composition and the biomechanics of radular teeth in the chiton Lepidochitona cinerea Krings, Wencke Brütt, Jan-Ole Gorb, Stanislav N. Front Zool Research BACKGROUND: The radula, a chitinous membrane with embedded teeth, is one important molluscan autapomorphy. In some taxa (Polyplacophora and Patellogastropoda) one tooth type (the dominant lateral tooth) was studied intensively in the last decades with regard to its mechanical properties, chemical and structural composition, and the relationship between these parameters. As the dominant lateral tooth is probably one of the best studied biological materials, it is surprising, that data on elements and mechanical properties of the other tooth types, present on a chiton radula, is lacking. RESULTS: We provide data on the elemental distribution and mechanical properties (hardness and elasticity, i.e. Young’s modulus) of all teeth from the Polyplacophora Lepidochitona cinerea (Linnaeus, 1767) [Chitonidae: Ischnochitonidae]. The ontogeny of elements, studied by energy-dispersive X-ray spectroscopy, and of the mechanical properties, determined by nanoindentation, was analysed in every individual tooth type. Additionally, we performed breaking stress experiments with teeth under dry and wet condition, highlighting the high influence of the water content on the mechanical behaviour of the radula. We thereby could determine the forces and stresses, teeth can resist, which were previously not studied in representatives of Polyplacophora. Overall, we were able to relate the mineral (iron, calcium) content with the mechanical parameters (hardness and Young’s modulus) and the breaking force and stress in every tooth type. This led to a better understanding of the relationship between structure, material, and function in radular teeth. Further, we aimed at determining the role of calcium for the mechanical behaviour of the teeth: we decalcified radulae by ethylene diamine tetra acetic acid and performed afterwards elemental analyses, breaking stress experiments, and nanoindentation. Among other things, we detected that wet and decalcified radular teeth could resist highest forces, since teeth have a higher range of bending motion leading to a higher capability of teeth to gain mechanical support from the adjacent tooth row. This indicates, that the tooth material is the result of a compromise between failure reduction and the ability to transfer forces onto the ingesta. CONCLUSION: We present novel data on the elemental composition, mechanical properties, and the mechanical behaviour of chiton teeth, which allows conclusions about tooth function. We could also relate the parameters mentioned, which contributes to our understanding on the origins of mechanical property gradients and the processes reducing structural failure in radular teeth. Additionally, we add more evidence, that the elemental composition of radular is probably species-specific and could be used as taxonomic character. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12983-022-00465-w. BioMed Central 2022-06-11 /pmc/articles/PMC9188181/ /pubmed/35690761 http://dx.doi.org/10.1186/s12983-022-00465-w Text en © The Author(s) 2022 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/ (https://creativecommons.org/publicdomain/zero/1.0/) ) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
spellingShingle Research
Krings, Wencke
Brütt, Jan-Ole
Gorb, Stanislav N.
Ontogeny of the elemental composition and the biomechanics of radular teeth in the chiton Lepidochitona cinerea
title Ontogeny of the elemental composition and the biomechanics of radular teeth in the chiton Lepidochitona cinerea
title_full Ontogeny of the elemental composition and the biomechanics of radular teeth in the chiton Lepidochitona cinerea
title_fullStr Ontogeny of the elemental composition and the biomechanics of radular teeth in the chiton Lepidochitona cinerea
title_full_unstemmed Ontogeny of the elemental composition and the biomechanics of radular teeth in the chiton Lepidochitona cinerea
title_short Ontogeny of the elemental composition and the biomechanics of radular teeth in the chiton Lepidochitona cinerea
title_sort ontogeny of the elemental composition and the biomechanics of radular teeth in the chiton lepidochitona cinerea
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9188181/
https://www.ncbi.nlm.nih.gov/pubmed/35690761
http://dx.doi.org/10.1186/s12983-022-00465-w
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