title: Structural and functional characterization of enamel pigmentation in shrews.
abstract: Pigmented tooth enamel occurs in several vertebrate clades, ranging from mammals to fish. Although an iron compound is associated with this orange to red colored pigmentation, its chemical and structural organization within the enamel is unknown. To determine the nature of the iron compound, we investigated heavily pigmented teeth of the northern short-tailed shrew Blarina brevicauda using combined characterization techniques such as scanning and transmission electron microscopy and synchrotron X-ray diffraction. We found that the pigmentation of the enamel with an iron content of around 8wt% results from a close to amorphous magnetite phase deposited around the nm-sized enamel crystals. Furthermore, the influence of the pigmentation on the enamel hardness was determined by nanoindentation measurements. Finally, the biomechanical function and biological context are discussed in light of the obtained results.
authors.affiliation: Max-Planck-Institute for Iron Research, 40237 Düsseldorf, Germany. Electronic address: m.dumont@mpie.de.
authors.forename: M
authors.initials: M
authors.lastname: Dumont
authors.affiliation: University of Mainz, Institute for Geosciences, 55128 Mainz, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Tütken
authors.affiliation: Max-Planck-Institute for Iron Research, 40237 Düsseldorf, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kostka
authors.affiliation: Max-Planck-Institute for Iron Research, 40237 Düsseldorf, Germany.
authors.forename: M J
authors.initials: MJ
authors.lastname: Duarte
authors.affiliation: Max-Planck-Institute for Iron Research, 40237 Düsseldorf, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Borodin
mesh_terms: D000818:Animals; D003743:Dental Enamel / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure; D055119:Elastic Modulus; D052203:Ferrosoferric Oxide / Q000737:chemistry; D006244:Hardness; D046529:Microscopy, Electron, Transmission; D056951:Photoelectron Spectroscopy; D010858:Pigmentation; D012788:Shrews / Q000033:anatomy & histology*; D014961:X-Ray Diffraction
chemical_list: D052203:Ferrosoferric Oxide
keywords: Amorphous magnetite; Enamel; Microstructure; Nanoindentation; Pigmentation; Shrew; Tooth; Transmission electron microscopy; X-ray diffraction