Deciphering the distribution of organic components in brachiopod shells by confocal laser scanning microscopy

Pérez‐Huerta, Alberto; Cusack, Maggie; Ball, Alexander D.; Williams, C. T.; Mackay, Sally

doi:10.1111/j.1365-2818.2008.01961.x

Cited by 9 publications

(6 citation statements)

References 10 publications

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“…Under blue light excitation, it was shown that each GI I region was associated with a couplet of one strongly fluorescing and one poorly fluorescing band. As was reported by Wanamaker et al (2009), the source of the intrinsic fluorescence within the shell of A. islandica is currently not well understood, but it has been suggested that a likely cause of fluorescence in calcitic brachiopods can be attributed to organic macromolecules (Pérez‐Huerta et al , 2008). It was concluded that that the poorly fluorescing band is representative of GI I, and this is consistent with the observations in this study, which demonstrate its increased mineralization.…”

Section: Discussionmentioning

confidence: 97%

Identification of growth increments in the shell of the bivalve mollusc Arctica islandica using backscattered electron imaging

Karney

Butler

Scourse

et al. 2010

Journal of Microscopy

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Summary Annually resolved growth increments in the shell of the bivalve mollusc Arctica islandica have previously been used in combination with geochemical measurements to successfully construct high‐resolution proxy records of past marine environmental conditions. However, to ensure the accuracy of these paleoenvironmental reconstructions it is essential that the annual growth series of increments within the examined shells are reliably identified, and can be distinguished from spurious lines caused by nonannual perturbations such as those resulting from storm disturbance. The current methods used for identifying the growth increment series are sometimes compromised because of ambiguity that results from the employed preparation methods. Here it is shown that backscattered electron imaging of polished shell cross sections may be used to clearly discriminate between the two compositionally and structurally distinct increments that comprise 1 year of outer shell growth. This method, involving minimal specimen preparation, is likely to be primarily useful as a validation technique of particular value in cases where increment identification using existing methods is difficult or ambiguous.

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Section: Discussionmentioning

confidence: 97%

Identification of growth increments in the shell of the bivalve mollusc Arctica islandica using backscattered electron imaging

Karney

Butler

Scourse

et al. 2010

Journal of Microscopy

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“…() and Pérez‐Huerta et al . (), fluorescence is triggered by organic macromolecules associated with chitin polysaccharides and proteins. Dark fluorescence colours commonly refer to portions of the shells that are relatively organic matter‐depleted and indicative for periods of slow shell growth.…”

Section: Interpretation and Discussionmentioning

confidence: 99%

Exploring the impact of diagenesis on (isotope) geochemical and microstructural alteration features in biogenic aragonite

et al. 2017

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For the Quaternary and Neogene, aragonitic biogenic and abiogenic carbonates are frequently exploited as archives of their environment. Conversely, pre‐Neogene aragonite is often diagenetically altered and calcite archives are studied instead. Nevertheless, the exact sequence of diagenetic processes and products is difficult to disclose from naturally altered material. Here, experiments were performed to understand biogenic aragonite alteration processes and products. Shell subsamples of the bivalve Arctica islandica were exposed to hydrothermal alteration. Thermal boundary conditions were set at 100°C, 175°C and 200°C. These comparably high temperatures were chosen to shorten experimental durations. Subsamples were exposed to different 18O‐depleted fluids for durations between two and twenty weeks. Alteration was documented using X‐ray diffraction, cathodoluminescence, fluorescence and scanning electron microscopy, as well as conventional and clumped isotope analyses. Experiments performed at 100°C show redistribution and darkening of organic matter, but lack evidence for diagenetic alteration, except in Δ47 which show the effects of annealing processes. At 175°C, valves undergo significant aragonite to calcite transformation and neomorphism. The δ18O signature supports transformation via dissolution and reprecipitation, but isotopic exchange is limited by fluid migration through the subsamples. Individual growth increments in these subsamples exhibit bright orange luminescence. At 200°C, valves are fully transformed to calcite and exhibit purple‐blue luminescence with orange bands. The δ18O and Δ47 signatures reveal exchange with the aqueous fluid, whereas δ13C remains unaltered in all experiments, indicating a carbonate‐buffered system. Clumped isotope temperatures in high‐temperature experiments show compositions in broad agreement with the measured temperature. Experimentally induced alteration patterns are comparable with individual features present in Pleistocene shells. This study represents a significant step towards sequential analysis of diagenetic features in biogenic aragonites and sheds light on reaction times and threshold limits. The limitations of a study restricted to a single test organism are acknowledged and call for refined follow‐up experiments.

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“…Currently, the source of the intrinsic fluorescence of A. islandica shells is unknown; A. islandica is known to precipitate its aragonite shell within an organic polymer matrix, which likely includes chitin polysaccharides and proteins (e.g., Addadi et al 2006;Cusack and Freer 2008;Dunca et al 2009). Perez-Huerta et al (2008) suggested that organic macromolecules associated with chitin polysaccharides and proteins in calcitic brachiopods (Terebratalia transversa and Novocrania anomala) are the likely cause of shell fluorescence in these species. The variability in the organic content within A. islandica growth increments has not been studied in any detail, and further work is required to establish the biogeochemical drivers of the fluorescence variability observed here.…”

Section: Discussionmentioning

confidence: 99%

A novel method for imaging internal growth patterns in marine mollusks: A fluorescence case study on the aragonitic shell of the marine bivalve Arctica islandica (Linnaeus)

Wanamaker

Baker

Butler

et al. 2009

Limnology & Ocean Methods

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In this article, we explore the use of fluorescence spectroscopy to image growth patterns in the marine bivalve Arctica islandica (L.). The method presented here does not require any chemical treatment of the polished shell section and yields results comparable to acetate peels of acid-etched shell sections and Mutveitreated shell sections. Further, our results indicate that the annual growth lines in A. islandica fluoresce in the blue light spectrum (450-490 nm), thus an ultraviolet source (mercury lamp) is not required. The reflected light entering the digital camera was filtered (510-540 nm) and later enhanced to emphasize the annual growth patterns. The fluorescence of annual growth lines was consistent among the four animals used in this study. Additionally, we measured growth increments in the umbo section of one A. islandica shell using both the traditional acetate method and fluorescence imaging. The two sets of measurements were highly correlated (r = 0.97; P < 0.0001). We suggest that the fluorescence imaging method presented here is a viable option for increment identification and measurement in this key marine archive. It is likely that the methods demonstrated here for A. islandica can easily be used/modified for other bivalve (mollusk) taxa. Fluorescence microscopy permits rapid analysis of shell growth patterns with minimal pretreatment and offers an objective method of determination of annual growth increments and lines.

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Deciphering the distribution of organic components in brachiopod shells by confocal laser scanning microscopy

Cited by 9 publications

References 10 publications

Identification of growth increments in the shell of the bivalve mollusc Arctica islandica using backscattered electron imaging

Identification of growth increments in the shell of the bivalve mollusc Arctica islandica using backscattered electron imaging

Exploring the impact of diagenesis on (isotope) geochemical and microstructural alteration features in biogenic aragonite

A novel method for imaging internal growth patterns in marine mollusks: A fluorescence case study on the aragonitic shell of the marine bivalve Arctica islandica (Linnaeus)

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