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The skeleton of the staghorn coral Acropora millepora: molecular and structural characterization.

Ramos-Silva P, Kaandorp J, Herbst F, Plasseraud L, Alcaraz G, Stern C, Corneillat M, Guichard N, Durlet C, Luquet G, Marin F - PLoS ONE (2014)

Bottom Line: Besides secreted proteins, there are a significant number of proteins with membrane attachment sites such as transmembrane domains and GPI anchors as well as proteins with integrin binding sites.Finally, we observe that the interaction of the acetic acid soluble SOM on the morphology of in vitro grown CaCO3 crystals is very pronounced when compared with the calcifying matrices of some mollusks.In light of these results, we wish to commend Acropora millepora as a model for biocalcification studies in scleractinians, from molecular and structural viewpoints.

View Article: PubMed Central - PubMed

Affiliation: UMR 6282 Biogéosciences, Université de Bourgogne, Dijon, France; Section Computational Science, Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands.

ABSTRACT
The scleractinian coral Acropora millepora is one of the most studied species from the Great Barrier Reef. This species has been used to understand evolutionary, immune and developmental processes in cnidarians. It has also been subject of several ecological studies in order to elucidate reef responses to environmental changes such as temperature rise and ocean acidification (OA). In these contexts, several nucleic acid resources were made available. When combined to a recent proteomic analysis of the coral skeletal organic matrix (SOM), they enabled the identification of several skeletal matrix proteins, making A. millepora into an emerging model for biomineralization studies. Here we describe the skeletal microstructure of A. millepora skeleton, together with a functional and biochemical characterization of its occluded SOM that focuses on the protein and saccharidic moieties. The skeletal matrix proteins show a large range of isoelectric points, compositional patterns and signatures. Besides secreted proteins, there are a significant number of proteins with membrane attachment sites such as transmembrane domains and GPI anchors as well as proteins with integrin binding sites. These features show that the skeletal proteins must have strong adhesion properties in order to function in the calcifying space. Moreover this data suggest a molecular connection between the calcifying epithelium and the skeletal tissue during biocalcification. In terms of sugar moieties, the enrichment of the SOM in arabinose is striking, and the monosaccharide composition exhibits the same signature as that of mucus of acroporid corals. Finally, we observe that the interaction of the acetic acid soluble SOM on the morphology of in vitro grown CaCO3 crystals is very pronounced when compared with the calcifying matrices of some mollusks. In light of these results, we wish to commend Acropora millepora as a model for biocalcification studies in scleractinians, from molecular and structural viewpoints.

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Raman spectra obtained from different crystals grown in vitro with the addition of different concentrations of ASM: (A) 0 µg.ml−1, (B) 0.1 µg.ml−1, (C) 1 µg.ml−1, (E) 5 µg.ml−1, (E) 20 µg.ml−1 and (F) 20 µg.ml−1.The visible bands clearly distinguish calcite and vaterite.
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pone-0097454-g005: Raman spectra obtained from different crystals grown in vitro with the addition of different concentrations of ASM: (A) 0 µg.ml−1, (B) 0.1 µg.ml−1, (C) 1 µg.ml−1, (E) 5 µg.ml−1, (E) 20 µg.ml−1 and (F) 20 µg.ml−1.The visible bands clearly distinguish calcite and vaterite.

Mentions: In order to double-check which polymorphs are present in the in vitro experiments, Raman spectroscopy was used. Spectra were acquired directly on several isolated crystals, and few results were selected for Figure 5. Spectra from crystals of Figure 5 A, B, C, E are typically that of calcite with three peaks at 281, 711 and 1086 cm−1, while those shown in Figure 5 D and F are characteristic of vaterite, in particular the peak at 301 cm−1 and the double peak at 1075–1090 cm−1. Therefore, the polymorphs formed were calcite and vaterite regardless of the concentration of ASM used.


The skeleton of the staghorn coral Acropora millepora: molecular and structural characterization.

Ramos-Silva P, Kaandorp J, Herbst F, Plasseraud L, Alcaraz G, Stern C, Corneillat M, Guichard N, Durlet C, Luquet G, Marin F - PLoS ONE (2014)

Raman spectra obtained from different crystals grown in vitro with the addition of different concentrations of ASM: (A) 0 µg.ml−1, (B) 0.1 µg.ml−1, (C) 1 µg.ml−1, (E) 5 µg.ml−1, (E) 20 µg.ml−1 and (F) 20 µg.ml−1.The visible bands clearly distinguish calcite and vaterite.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4043741&req=5

pone-0097454-g005: Raman spectra obtained from different crystals grown in vitro with the addition of different concentrations of ASM: (A) 0 µg.ml−1, (B) 0.1 µg.ml−1, (C) 1 µg.ml−1, (E) 5 µg.ml−1, (E) 20 µg.ml−1 and (F) 20 µg.ml−1.The visible bands clearly distinguish calcite and vaterite.
Mentions: In order to double-check which polymorphs are present in the in vitro experiments, Raman spectroscopy was used. Spectra were acquired directly on several isolated crystals, and few results were selected for Figure 5. Spectra from crystals of Figure 5 A, B, C, E are typically that of calcite with three peaks at 281, 711 and 1086 cm−1, while those shown in Figure 5 D and F are characteristic of vaterite, in particular the peak at 301 cm−1 and the double peak at 1075–1090 cm−1. Therefore, the polymorphs formed were calcite and vaterite regardless of the concentration of ASM used.

Bottom Line: Besides secreted proteins, there are a significant number of proteins with membrane attachment sites such as transmembrane domains and GPI anchors as well as proteins with integrin binding sites.Finally, we observe that the interaction of the acetic acid soluble SOM on the morphology of in vitro grown CaCO3 crystals is very pronounced when compared with the calcifying matrices of some mollusks.In light of these results, we wish to commend Acropora millepora as a model for biocalcification studies in scleractinians, from molecular and structural viewpoints.

View Article: PubMed Central - PubMed

Affiliation: UMR 6282 Biogéosciences, Université de Bourgogne, Dijon, France; Section Computational Science, Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands.

ABSTRACT
The scleractinian coral Acropora millepora is one of the most studied species from the Great Barrier Reef. This species has been used to understand evolutionary, immune and developmental processes in cnidarians. It has also been subject of several ecological studies in order to elucidate reef responses to environmental changes such as temperature rise and ocean acidification (OA). In these contexts, several nucleic acid resources were made available. When combined to a recent proteomic analysis of the coral skeletal organic matrix (SOM), they enabled the identification of several skeletal matrix proteins, making A. millepora into an emerging model for biomineralization studies. Here we describe the skeletal microstructure of A. millepora skeleton, together with a functional and biochemical characterization of its occluded SOM that focuses on the protein and saccharidic moieties. The skeletal matrix proteins show a large range of isoelectric points, compositional patterns and signatures. Besides secreted proteins, there are a significant number of proteins with membrane attachment sites such as transmembrane domains and GPI anchors as well as proteins with integrin binding sites. These features show that the skeletal proteins must have strong adhesion properties in order to function in the calcifying space. Moreover this data suggest a molecular connection between the calcifying epithelium and the skeletal tissue during biocalcification. In terms of sugar moieties, the enrichment of the SOM in arabinose is striking, and the monosaccharide composition exhibits the same signature as that of mucus of acroporid corals. Finally, we observe that the interaction of the acetic acid soluble SOM on the morphology of in vitro grown CaCO3 crystals is very pronounced when compared with the calcifying matrices of some mollusks. In light of these results, we wish to commend Acropora millepora as a model for biocalcification studies in scleractinians, from molecular and structural viewpoints.

Show MeSH
Related in: MedlinePlus