Organic macromolecules in shells of Arctica islandica: comparison with nacroprismatic bivalve shells

Agbaje, Oluwatoosin B. A.; Thomas, Damon; Mclnerney, Bernie V.; Molloy, Mark P.; Jacob, Dorrit E.

doi:10.1007/s00227-017-3238-2

Cited by 16 publications

(13 citation statements)

References 43 publications

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“…Compared with the prism-nacre microstructure of mollusc shells, the crossed-lamellar architecture of the T. derasa shell is highly mineralized with only 0.9 wt% total organic content compared with greater than 3 wt% in nacre [ 45 ]. Its structure is distinctly different and overall more complex than the nacro-prismatic structure [ 12 ], with three hierarchy orders of aragonite laths creating an interlocking fabric reminiscent of plywood ( figure 1 ) [ 7 , 8 ].…”

Section: Discussionmentioning

confidence: 99%

Architecture of crossed-lamellar bivalve shells: the southern giant clam (Tridacna derasa, Röding, 1798)

et al. 2017

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Tridacna derasa shells show a crossed lamellar microstructure consisting of three hierarchical lamellar structural orders. The mineral part is intimately intergrown with 0.9 wt% organics, namely polysaccharides, glycosylated and unglycosylated proteins and lipids, identified by Fourier transform infrared spectrometry. Transmission electron microscopy shows nanometre-sized grains with irregular grain boundaries and abundant voids. Twinning is observed across all spatial scales and results in a spread of the crystal orientation angles. Electron backscatter diffraction analysis shows a strong fibre texture with the [001] axes of aragonite aligned radially to the shell surface. The aragonitic [100] and [010] axes are oriented randomly around [001]. The random orientation of anisotropic crystallographic directions in this plane reduces anisotropy of the Young's modulus and adds to the optimization of mechanical properties of bivalve shells.

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Section: Discussionmentioning

confidence: 99%

Architecture of crossed-lamellar bivalve shells: the southern giant clam (Tridacna derasa, Röding, 1798)

et al. 2017

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“…However, this type of biomineralization occurs in mollusks with nacro-prismatic shells [81,82] with high organic content (ca. 3.5 wt%, [83]) and likely does not play a major role in A. islandica shells with much lower amounts of organics (1.65 wt%, [83]). Furthermore, nacro-prismatic shells contain sheets of β-chitin and silk-like proteins [84], which are required for the building of such organic envelopes.…”

Section: Plos Onementioning

confidence: 98%

Temperature-induced microstructural changes in shells of laboratory-grown Arctica islandica (Bivalvia)

Höche¹,

Walliser²,

Winter

et al. 2021

PLoS ONE

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Bivalve shells are increasingly used as archives for high-resolution paleoclimate analyses. However, there is still an urgent need for quantitative temperature proxies that work without knowledge of the water chemistry–as is required for δ18O-based paleothermometry–and can better withstand diagenetic overprint. Recently, microstructural properties have been identified as a potential candidate fulfilling these requirements. So far, only few different microstructure categories (nacreous, prismatic and crossed-lamellar) of some short-lived species have been studied in detail, and in all such studies, the size and/or shape of individual biomineral units was found to increase with water temperature. Here, we explore whether the same applies to properties of the crossed-acicular microstructure in the hinge plate of Arctica islandica, the microstructurally most uniform shell portion in this species. In order to focus solely on the effect of temperature on microstructural properties, this study uses bivalves that grew their shells under controlled temperature conditions (1, 3, 6, 9, 12 and 15°C) in the laboratory. With increasing temperature, the size of the largest individual biomineral units and the relative proportion of shell occupied by the crystalline phase increased. The size of the largest pores, a specific microstructural feature of A. islandica, whose potential role in biomineralization is discussed here, increased exponentially with culturing temperature. This study employs scanning electron microscopy in combination with automated image processing software, including an innovative machine learning–based image segmentation method. The new method greatly facilitates the recognition of microstructural entities and enables a faster and more reliable microstructural analysis than previously used techniques. Results of this study establish the new microstructural temperature proxy in the crossed-acicular microstructures of A. islandica and point to an overarching control mechanism of temperature on the micrometer-scale architecture of bivalve shells across species boundaries.

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“…Robust temperate marine shells, such as those used in this study, consist mainly of mineral CaCO 3 (with various amounts of MgCO 3 ), but some are additionally strengthened by layers of proteins, polysaccharides and pigments – generally lumped into the category of “organic material”. Molluscan carbonate is among the most organic‐rich, with 2–4% of the shell by weight being organic 89 . The weight loss reported here following pretreatment (means of 0.6 to 5.5 wt%) suggests that most if not all organic material was removed, either by combustion or molecular dissociation.…”

Section: Discussionmentioning

confidence: 67%

Effect of removal of organic material on stable isotope ratios in skeletal carbonate from taxonomic groups with complex mineralogies

Key

Smith

Phillips

et al. 2020

Rapid Comm Mass Spectrometry

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Rationale Stable oxygen and carbon isotope ratios are one of the most accurate ways of determining environmental changes in the past, which are used to predict future environmental change. Biogenic carbonates from marine organisms are the most common source of samples for stable isotope analysis. Before they are analyzed by mass spectrometry, any organic material is traditionally removed by one of three common pretreatment methods: roasting, bleaching, or with hydrogen peroxide at various strengths and durations. Methods This study compares δ18O and δ13C values in a control with no pretreatment with those from five different pretreatment methods using conventional acid digestion mass spectrometry. The objectives are to: assess the impact of the most common pretreatment methods on δ18O and δ13C values from (1) taxonomically underrepresented groups in previous studies, and (2) those that precipitate a wide range of biomineralogies, in the debate of whether to pretreat or not to pretreat. We analyzed the following biomineralogically complex temperate marine organisms from southern New Zealand: four species of bryozoans, four species of molluscs, two species of arthropods, and one species each of annelid, red alga, brachiopod, and echinoderm (test plates and spines treated separately). These species precipitate aragonite, High‐, Intermediate‐, and/or Low‐Mg calcite (LMC) in their skeletons. We used linear mixed statistical models to compare the effects of the pretreatments and mineralogical composition on their δ18O and δ13C values. Results Roasting was the most effective pretreatment for the removal of organic matter and light H2O2 the least, but the former had corresponding impacts on isotope ratios. δ18O values were not directly affected by wt% MgCO3, but they were significantly affected by the interaction of roasting and wt% MgCO3. This same negative effect of roasting on species with higher wt% MgCO3 occurred in δ13C values, but it was much more pronounced in δ18O values. Both H2O2 pretreatments significantly and negatively affected δ18O values at higher wt% MgCO3. Neither bleaching pretreatment significantly affected δ18O values. δ13C values were most negatively affected in skeletons with high wt% MgCO3. There was also a strong negative roasting effect and more so at higher wt% MgCO3. Bleaching and H2O2 did not significantly affect δ13C values. Conclusions Based on these results, and when using skeletal carbonate of complex mineralogies, we recommend considering the abandonment of pretreatment of biogenic carbonate for stable isotope analysis due to confounded results from previous studies, difficulties with preparation, and/or the absence of significant effects of organic material on isotope ratios. If pretreatment is necessary, avoid roasting especially at higher temperatures and durations, use minimal bleaching, and in general avoid using High‐Mg calcite species in O and C stable isotope studies. If bleaching is used, clearly indicate the concentration and duration of exposure.

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Organic macromolecules in shells of Arctica islandica: comparison with nacroprismatic bivalve shells

Cited by 16 publications

References 43 publications

Architecture of crossed-lamellar bivalve shells: the southern giant clam (Tridacna derasa, Röding, 1798)

Architecture of crossed-lamellar bivalve shells: the southern giant clam (Tridacna derasa, Röding, 1798)

Temperature-induced microstructural changes in shells of laboratory-grown Arctica islandica (Bivalvia)

Effect of removal of organic material on stable isotope ratios in skeletal carbonate from taxonomic groups with complex mineralogies

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