Structural investigations of octocoral sclerites

Majoran, Stefan

doi:10.1111/j.1463-6409.1987.tb00074.x

Cited by 11 publications

(21 citation statements)

References 4 publications

(3 reference statements)

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“…We noted that the sclerite shape in Sinularia sp. was different from that of other Alcyonacea [3], [23] and Gorgonacea [24]. Scale-shaped or rounded sclerites with a spherulitic structure were formed by gorgonians while spindles and rod-shaped spicules were common among gorgonians and pennatulids.…”

Section: Resultsmentioning

confidence: 81%

Analysis of the Proteinaceous Components of the Organic Matrix of Calcitic Sclerites from the Soft Coral Sinularia sp.

et al. 2013

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An organic matrix consisting of a protein-polysaccharide complex is generally accepted as an important medium for the calcification process. While the role this “calcified organic matrix” plays in the calcification process has long been appreciated, the complex mixture of proteins that is induced and assembled during the mineral phase of calcification remains uncharacterized in many organisms. Thus, we investigated organic matrices from the calcitic sclerites of a soft coral, Sinularia sp., and used a proteomic approach to identify the functional matrix proteins that might be involved in the biocalcification process. We purified eight organic matrix proteins and performed in-gel digestion using trypsin. The tryptic peptides were separated by nano-liquid chromatography (nano-LC) and analyzed by tandem mass spectrometry (MS/MS) using a matrix-assisted laser desorption/ionization (MALDI) – time-of-flight-time-of-flight (TOF-TOF) mass spectrometer. Periodic acid Schiff staining of an SDS-PAGE gel indicated that four proteins were glycosylated. We identified several proteins, including a form of actin, from which we identified a total of 183 potential peptides. Our findings suggest that many of those peptides may contribute to biocalcification in soft corals.

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Section: Resultsmentioning

confidence: 81%

Analysis of the Proteinaceous Components of the Organic Matrix of Calcitic Sclerites from the Soft Coral Sinularia sp.

et al. 2013

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“…4D). Concentric patterns are a systematic feature of sclerites and are commonly interpreted as the result of successive stages of growth (Kingsley and Watabe 1982;Majoran 1987;Sethmann et al 2007). The complex shape of these objects and the concentric arrangement of crystalline layers might suggest large variations of crystallographic orientations of the calcite submicrometer crystals inside the sclerite.…”

Section: Resultsmentioning

confidence: 99%

“…The presence of sclerites in living tissues is a well-known feature of octocorals (Bayer 1956;Lowenstam and Weiner 1989;Majoran 1987;Schmidt 1924;Sethmann et al 2007). Sclerites have attracted the interest of the scientific community for a long time, initially for taxonomy purpose and later for their remarkable architecture (Kingsley and Watabe 1982;Lowenstam and Weiner 1989).…”

Section: Introductionmentioning

confidence: 97%

Mesoscale twinning and crystallographic registers in biominerals

Floquet

Vielzeuf

2011

American Mineralogist

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Mesocrystals attract increasing interest in the fields of physics, chemistry, materials, and Earth sciences. Yet, structural properties of this new class of solid materials are not fully described. Biominerals often display complex hierarchical mesocrystalline organizations. We report on the crystallography of sclerites, which are small (∼80 µm), beautifully shaped calcitic biomineral structures found in the living tissues of octocorals. Despite a layered concentric structure, the submicrometer crystalline units constituting the sclerites display a remarkably simple crystallographic organization of similarly oriented units with only a low degree of misorientation between them. Some sclerites display crystallographic sectors, leading to the concept of "mesotwin." A mesotwin is to a twin what a "mesocrystal" is to a crystal: an analog with defects. On the basis of EBSD data, we propose a simple conceptual crystallographic model that accounts for the observed features. This model involves different rhombohedral unit blocks, with identical shapes and volumes, but different crystallographic faces. EBSD data show that quite unexpectedly slight misorientations of crystallites in the sclerites are not at random but organized around the three equivalent a axes of the hexagonal unit cell of calcite. In a subtle way, the overall organization and morphologies of the red coral sclerites are connected to the calcite crystallography.

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“…4). Note, that the belonging to some measured data to internodes (without central canal) cannot be excluded (see discussion in the text) Growth stages, expressed by concentric rings/bandings and reported for instance from extant and fossil gorgonians, particularly sections of their internodes (Langer 1989;Noé and Dullo 2006;Sánchez et al 2004;Noé et al 2007), or any other microstructural features (e.g., Bayer 1981a;Majoran 1987;Lewis et al 1992;Macintyre et al 2000;Sethmann et al 2007) are not visible in our specimens due to recrystallization. The observable homogeneous sparry calcite, however, makes an original alternation of horny and calcareous material improbable.…”

Section: Discussionmentioning

confidence: 83%