Mesoscopic crystallographic textures on shells of a hyaline radial foraminifer Ammonia beccarii

Nakajima, Kimiko; Nagai, Yukiko; Suzuki, Masane; Oaki, Yuya; Naito, Kimiyoshi; Tanaka, Yoshihisa; Toyofuku, Takashi; Imai, Hiroaki

doi:10.1039/c6ce01611a

Cited by 13 publications

(16 citation statements)

References 36 publications

(46 reference statements)

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“…Our finding that El/Ca peaks are co-located with organic linings (Fig. 1) is in line with other studies on intra-specimen element distribution in Rotallid (benthic) foraminifera 8,33,37,52,64 . An Atom Probe Tomography-Time-of-flight-Secondary Ionization Mass Spectrometry study showed that the interface of the organic template in O. universa is enriched in Na and Mg 44 , suggesting that metals other than Ca 2+ might be bound to charged functional groups, or that incorporation of these elements is increased due to lattice strain induced by the organic template.…”

Section: Discussionsupporting

confidence: 93%

Element banding and organic linings within chamber walls of two benthic foraminifera

Geerken

Nooijer

Roepert

et al. 2019

Sci Rep

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Trace and minor elements incorporated in foraminiferal shells are among the most used proxies for reconstructing past environmental conditions. A prominent issue concerning these proxies is that the inter-specimen variability in element composition is often considerably larger than the variability associated with the environmental conditions for which the proxy is used. Within a shell of an individual specimen the trace and minor elements are distributed in the form of bands of higher and lower concentrations. It has been hypothesized that differences in specimen-specific element banding patterns cause the inter-specimen and inter-species variability observed in average element composition, thereby reducing the reliability of proxies. To test this hypothesis, we compared spatial distributions of Mg, Na, Sr, K, S, P and N within chamber walls of two benthic foraminiferal species ( Amphistegina lessonii and Ammonia tepida ) with largely different average Mg content. For both species the selected specimens were grown at different temperatures and salinities to additionally assess how these parameters influence the element concentrations within the shell wall. Our results show that Mg, Na, Sr and K are co-located within shells, and occur in bands that coincide with organic linings but extend further into the calcite lamella. Changes in temperature or salinity modulate the element-banding pattern as a whole, with peak and trough heights co-varying rather than independently affected by these two environmental parameters. This means that independent changes in peak or trough height do not explain differences in average El/Ca between specimens. These results are used to evaluate and synthesize models of underlying mechanisms responsible for trace and minor element partitioning during calcification in foraminifera.

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Section: Discussionsupporting

confidence: 93%

Element banding and organic linings within chamber walls of two benthic foraminifera

Geerken

Nooijer

Roepert

et al. 2019

Sci Rep

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“…In specimen #1 and #2, the form of the calcareous materials is not of a typical crystalline appearance but appeared rather irregular. This is different from the previously reported appearance of calcitic walls of this species (Nakajima et al, 2016). Elemental analysis results with SEM-EDS support that these structures are indeed calcium carbonate, but the crystallographical structure remain uncharacterized and is a subject of future studies.…”

Section: Decontrasting

confidence: 99%

“…Elemental analysis results with SEM-EDS support that these structures are indeed calcium carbonate, but the crystallographical structure remain uncharacterized and is a subject of future studies. Submicron periodic lateral layers (∼200-450 nm) in a single lamellar structure has been reported previously and was considered to represent the smallest unit of crystal growth in foraminifera (Nakajima et al, 2016). These are comparable to crystals found in the planktonic Globigerina sp.…”

Section: Desupporting

confidence: 57%

“…Regarding the calcareous layer, it is evident that calcium carbonate is present in both calcareous layers (outer and inner calcareous layers) in all individuals observed in this study (Figure 8). In specimens #3-#5, especially, it is presumed that the nature of the calcium carbonate are calcite crystals because they resemble ordinary test cross sections (Nakajima et al, 2016). In specimen #1 and #2, the form of the calcareous materials is not of a typical crystalline appearance but appeared rather irregular.…”

Section: Dementioning

confidence: 99%

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Reading the Fine Print: Ultra-Microstructures of Foraminiferal Calcification Revealed Using Focused Ion Beam Microscopy

Nagai¹,

Uematsu²,

Wani³

et al. 2018

Front. Mar. Sci.

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The elemental composition of calcite is of critical value in paleoceanographic reconstructions, yet little is known about biological processes underlying elemental uptake by foraminifers during calcification. Especially crucial in the understanding of elemental composition and distribution is the involvement of organic templates separating different layers of calcite forming the wall of a foraminiferal chamber. In this study, we applied the focused ion beam (FIB) scanning electron microscopy (SEM) technique to the site of calcification (SOC) in a newly growing chamber of Ammonia "beccarii", a benthic foraminifer, to reveal the ultra-and microstructure during calcification. This allowed cross-sections of both soft and hard tissues, allowing detailed observation of the SOC across a series of calcification stages. For the first time, we show that numerous voids of calcareous layers and internal organic structures are present within the SOC during the calcification process. The series of SEM observations suggest that organic layers are actively involved in calcite precipitation. We provide the first evidence that the SOC is isolated from surrounding seawater during calcification. Our findings improve the understanding of foraminiferal biomineralization and characterize key conditions under which element partitioning and isotope fractionation occur.

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“…Most approaches to unravel biomineralization processes in foraminifera calcification focus solely on single species and mainly investigate shell chemistry to retrace element uptake. Still, shell formation is a combination of not only chemical but also biological processes, limited by structural constraints like organic templates and crystallographic orientation of the calcium carbonate crystals (e.g., Nakajima et al, 2016;Nagai et al, 2018;Tyszka et al, 2019), and all these aspects have to be considered when trying to explain calcification on successive taxonomic levels. This paper aims to provide new insights on the structural constraints and features of shell construction, as observed in the shell wall and on the shell surface.…”

Section: Introductionmentioning

confidence: 99%

Novel Method to Image and Quantify Cogwheel Structures in Foraminiferal Shells

et al. 2020

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Most studies designed to better understand biomineralization by foraminifera focus mainly on their shell chemistry in order to retrace processes responsible for element uptake and shell formation. Still, shell formation is a combination of not only chemical and biological processes, but is also limited by structural features. Since the processes involved in the formation of the foraminifera shell remains elusive, new focus has been put on potential structural constraints during shell formation. Revealing structural details of shells of foraminifera might increase our mechanistic understanding of foraminifera calcification, and even explain species-specific differences in element incorporation. Recently, shell structures have been studied in increasingly higher resolution and detail. This paper aims to provide new insights on the structural features on foraminifera shells, so-called cogwheels, which can be observed in the shell wall and at its surface. Here, we present a novel method to image and quantify these cogwheel structures, using field specimens from different environments and ecological groups, including benthic and planktonic species. Application of this method allows for comparing shell structures at specimen and species level, to unravel potential drivers of shell formation.

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Mesoscopic crystallographic textures on shells of a hyaline radial foraminifer Ammonia beccarii

Cited by 13 publications

References 36 publications

Element banding and organic linings within chamber walls of two benthic foraminifera

Element banding and organic linings within chamber walls of two benthic foraminifera

Reading the Fine Print: Ultra-Microstructures of Foraminiferal Calcification Revealed Using Focused Ion Beam Microscopy

Novel Method to Image and Quantify Cogwheel Structures in Foraminiferal Shells

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