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Foster B, Hugosson F, Scucchia F, Enjolras C, Babonis LS, Hoaen W, Martindale MQ. A novel in vivo system to study coral biomineralization in the starlet sea anemone, Nematostella vectensis. iScience 2024; 27:109131. [PMID: 38384856 PMCID: PMC10879693 DOI: 10.1016/j.isci.2024.109131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/18/2023] [Accepted: 02/01/2024] [Indexed: 02/23/2024] Open
Abstract
Coral conservation requires a mechanistic understanding of how environmental stresses disrupt biomineralization, but progress has been slow, primarily because corals are not easily amenable to laboratory research. Here, we highlight how the starlet sea anemone, Nematostella vectensis, can serve as a model to interrogate the cellular mechanisms of coral biomineralization. We have developed transgenic constructs using biomineralizing genes that can be injected into Nematostella zygotes and designed such that translated proteins may be purified for physicochemical characterization. Using fluorescent tags, we confirm the ectopic expression of the coral biomineralizing protein, SpCARP1, in Nematostella. We demonstrate via calcein staining that SpCARP1 concentrates calcium ions in Nematostella, likely initiating the formation of mineral precursors, consistent with its suspected role in corals. These results lay a fundamental groundwork for establishing Nematostella as an in vivo system to explore the evolutionary and cellular mechanisms of coral biomineralization, improve coral conservation efforts, and even develop novel biomaterials.
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Affiliation(s)
- Brent Foster
- The Whitney Laboratory for Marine Bioscience, Department of Biology, University of Florida, Gainesville, FL 32080, USA
| | - Fredrik Hugosson
- The Whitney Laboratory for Marine Bioscience, Department of Biology, University of Florida, Gainesville, FL 32080, USA
| | - Federica Scucchia
- The Whitney Laboratory for Marine Bioscience, Department of Biology, University of Florida, Gainesville, FL 32080, USA
| | - Camille Enjolras
- The Whitney Laboratory for Marine Bioscience, Department of Biology, University of Florida, Gainesville, FL 32080, USA
- Institute of Human Genetics, CNRS, Montpellier 34090, France
| | - Leslie S. Babonis
- The Whitney Laboratory for Marine Bioscience, Department of Biology, University of Florida, Gainesville, FL 32080, USA
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - William Hoaen
- School of Biosciences, Cardiff University, Cardiff CF10 3AT, UK
| | - Mark Q. Martindale
- The Whitney Laboratory for Marine Bioscience, Department of Biology, University of Florida, Gainesville, FL 32080, USA
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2
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Gindele MB, Vinod-Kumar S, Rochau J, Boemke D, Groß E, Redrouthu VS, Gebauer D, Mathies G. Colloidal pathways of amorphous calcium carbonate formation lead to distinct water environments and conductivity. Nat Commun 2024; 15:80. [PMID: 38167336 PMCID: PMC10761707 DOI: 10.1038/s41467-023-44381-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 12/12/2023] [Indexed: 01/05/2024] Open
Abstract
CaCO3 is the most abundant biomineral and a major constituent of incrustations arising from water hardness. Polycarboxylates play key roles in controlling mineralization. Herein, we present an analytical and spectroscopic study of polycarboxylate-stabilized amorphous CaCO3 (ACC) and its formation via a dense liquid precursor phase (DLP). Polycarboxylates facilitate pronounced, kinetic bicarbonate entrapment in the DLP. Since bicarbonate is destabilized in the solid state, DLP dehydration towards solid ACC necessitates the formation of locally calcium deficient sites, thereby inhibiting nucleation. Magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy of poly-aspartate-stabilized ACC reveals the presence of two distinct environments. The first contains immobile calcium and carbonate ions and structural water molecules, undergoing restricted, anisotropic motion. In the second environment, water molecules undergo slow, but isotropic motion. Indeed, conductive atomic force microscopy (C-AFM) reveals that ACC conducts electrical current, strongly suggesting that the mobile environment pervades the bulk of ACC, with dissolved hydroxide ions constituting the charge carriers. We propose that the distinct environments arise from colloidally stabilized interfaces of DLP nanodroplets, consistent with the pre-nucleation cluster (PNC) pathway.
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Affiliation(s)
- Maxim B Gindele
- Institute of Inorganic Chemistry, Leibniz University Hannover, Callinstr. 9, 30167, Hannover, Germany
| | - Sanjay Vinod-Kumar
- Department of Chemistry, University of Konstanz, Universitätsstr. 10, 78464, Konstanz, Germany
| | - Johannes Rochau
- Institute of Inorganic Chemistry, Leibniz University Hannover, Callinstr. 9, 30167, Hannover, Germany
| | - Daniel Boemke
- Institute of Inorganic Chemistry, Leibniz University Hannover, Callinstr. 9, 30167, Hannover, Germany
| | - Eduard Groß
- Institute of Inorganic Chemistry, Leibniz University Hannover, Callinstr. 9, 30167, Hannover, Germany
| | | | - Denis Gebauer
- Institute of Inorganic Chemistry, Leibniz University Hannover, Callinstr. 9, 30167, Hannover, Germany.
| | - Guinevere Mathies
- Department of Chemistry, University of Konstanz, Universitätsstr. 10, 78464, Konstanz, Germany.
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3
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Conci N, Griesshaber E, Rivera-Vicéns RE, Schmahl WW, Vargas S, Wörheide G. Molecular and mineral responses of corals grown under artificial Calcite Sea conditions. GEOBIOLOGY 2024; 22:e12586. [PMID: 38385602 DOI: 10.1111/gbi.12586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 01/16/2024] [Indexed: 02/23/2024]
Abstract
The formation of skeletal structures composed of different calcium carbonate polymorphs (e.g. aragonite and calcite) appears to be both biologically and environmentally regulated. Among environmental factors influencing aragonite and calcite precipitation, changes in seawater conditions-primarily in the molar ratio of magnesium and calcium during so-called 'Calcite' (mMg:mCa below 2) or 'Aragonite' seas (mMg:mCa above 2)-have had profound impacts on the distribution and performance of marine calcifiers throughout Earth's history. Nonetheless, the fossil record shows that some species appear to have counteracted such changes and kept their skeleton polymorph unaltered. Here, the aragonitic octocoral Heliopora coerulea and the aragonitic scleractinian Montipora digitata were exposed to Calcite Sea-like mMg:mCa with various levels of magnesium and calcium concentration, and changes in both the mineralogy (i.e. CaCO3 polymorph) and gene expression were monitored. Both species maintained aragonite deposition at lower mMg:mCa ratios, while concurrent calcite presence was only detected in M. digitata. Despite a strong variability between independent experimental replicates for both species, the expression for a set of putative calcification-related genes, including known components of the M. digitata skeleton organic matrix (SkOM), was found to consistently change at lower mMg:mCa. These results support the previously proposed involvements of the SkOM in counteracting decreases in seawater mMg:mCa. Although no consistent expression changes in calcium and magnesium transporters were observed, down-regulation calcium channels in H. coerulea in one experimental replicate and at an mMg:mCa of 2.5, pointing to a possible active calcium uptake regulation by the corals under altered mMg:mCa.
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Affiliation(s)
- Nicola Conci
- Department of Earth and Environmental Sciences, Paleontology and Geobiology, Ludwig-Maximilians-Universität, Munich, Germany
| | - Erika Griesshaber
- Department of Earth and Environmental Sciences, Crystallography, Ludwig-Maximilians-Universität, Munich, Germany
- GeoBio-Center LMU, Ludwig-Maximilians-Universität, Munich, Germany
| | - Ramón E Rivera-Vicéns
- Department of Earth and Environmental Sciences, Paleontology and Geobiology, Ludwig-Maximilians-Universität, Munich, Germany
| | - Wolfgang W Schmahl
- Department of Earth and Environmental Sciences, Crystallography, Ludwig-Maximilians-Universität, Munich, Germany
- GeoBio-Center LMU, Ludwig-Maximilians-Universität, Munich, Germany
- SNSB - Mineralogische Staatssammlung, Munich, Germany
| | - Sergio Vargas
- Department of Earth and Environmental Sciences, Paleontology and Geobiology, Ludwig-Maximilians-Universität, Munich, Germany
| | - Gert Wörheide
- Department of Earth and Environmental Sciences, Paleontology and Geobiology, Ludwig-Maximilians-Universität, Munich, Germany
- GeoBio-Center LMU, Ludwig-Maximilians-Universität, Munich, Germany
- SNSB - Bayerische Staatssammlung für Paläontologie und Geologie, Munich, Germany
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4
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Milita S, Zaquin T, Fermani S, Montroni D, Pinkas I, Barba L, Falini G, Mass T. Assembly of the Intraskeletal Coral Organic Matrix during Calcium Carbonate Formation. CRYSTAL GROWTH & DESIGN 2023; 23:5801-5811. [PMID: 37547884 PMCID: PMC10401569 DOI: 10.1021/acs.cgd.3c00401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 07/01/2023] [Indexed: 08/08/2023]
Abstract
Scleractinia coral skeleton formation occurs by a heterogeneous process of nucleation and growth of aragonite in which intraskeletal soluble organic matrix molecules, usually referred to as SOM, play a key role. Several studies have demonstrated that they influence the shape and polymorphic precipitation of calcium carbonate. However, the structural aspects that occur during the growth of aragonite have received less attention. In this research, we study the deposition of calcium carbonate on a model substrate, silicon, in the presence of SOM extracted from the skeleton of two coral species representative of different living habitats and colonization strategies, which we previously characterized. The study is performed mainly by grazing incidence X-ray diffraction with the support of Raman spectroscopy and electron and optical microscopies. The results show that SOM macromolecules once adsorbed on the substrate self-assembled in a layered structure and induced the oriented growth of calcite, inhibiting the formation of vaterite. Differently, when SOM macromolecules were dispersed in solution, they induced the deposition of amorphous calcium carbonate (ACC), still preserving a layered structure. The entity of these effects was species-dependent, in agreement with previous studies. In conclusion, we observed that in the setup required by the experimental procedure, the SOM from corals appears to present a 2D lamellar structure. This structure is preserved when the SOM interacts with ACC but is lost when the interaction occurs with calcite. This knowledge not only is completely new for coral biomineralization but also has strong relevance in the study of biomineralization on other organisms.
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Affiliation(s)
- Silvia Milita
- CNR—Institute
for Microelectronic and Microsystems, via Gobetti 101, Bologna 40129, Italy
| | - Tal Zaquin
- Department
of Marine Biology, The Leon H. Charney School of Marine Sciences, University of Haifa, Mt. Carmel, Haifa 3498838, Israel
| | - Simona Fermani
- Department
of Chemistry “Giacomo Ciamician”, University of Bologna, via Selmi 2, Bologna 40126, Italy
- Interdepartmental
Centre for Industrial Research Health Sciences & Technologie, University of Bologna, Bologna 40064, Italy
| | - Devis Montroni
- Department
of Chemistry “Giacomo Ciamician”, University of Bologna, via Selmi 2, Bologna 40126, Italy
| | - Iddo Pinkas
- Department
of Chemical Research Support, Weizmann Institute
of Science, Rehovot 76100, Israel
| | - Luisa Barba
- CNR
-Institute
of Crystallography, Elettra Synchrotron, Trieste I-34100, Italy
| | - Giuseppe Falini
- Department
of Chemistry “Giacomo Ciamician”, University of Bologna, via Selmi 2, Bologna 40126, Italy
- CNR,
Institute for Nanostructured
Materials, via Gobetti
101, Bologna 40129, Italy
| | - Tali Mass
- Department
of Marine Biology, The Leon H. Charney School of Marine Sciences, University of Haifa, Mt. Carmel, Haifa 3498838, Israel
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5
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Mahadevan G, Brahma RK, Kini RM, Valiyaveettil S. Purification of Intramineral Peptides from Cuttlebones and In Vitro Activity in CaCO 3 Biomineralization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:7249-7257. [PMID: 37201193 DOI: 10.1021/acs.langmuir.2c03433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Living organisms develop functional hard structures such as teeth, bones, and shells from calcium salts through mineralization for managing vital functions to sustain life. However, the exact mechanism or role of biomolecules such as proteins and peptides in the biomineralization process to form defect-free hierarchical structures in nature is poorly understood. In this study, we have extracted, purified, and characterized five major peptides (CBP1-CBP5) from the soluble organic materials (SOMs) of cuttlefish bone (CB) and used for the in vitro mineralization of calcium carbonate crystals. The SOMs induced nucleation of the calcite phase at low concentrations and the vaterite phase at high concentrations. The purified peptides nucleated calcite crystals and enhanced aggregation under laboratory conditions. Among five peptides, only CBP2 and CBP3 showed concentration-dependent nucleation, aggregation, and morphological changes of the calcite crystals within 12 h. Circular dichroism studies showed that the peptides CBP2 and CBP3 are in alpha helix and β-sheet conformation, respectively, in solution. CBP1 and CBP4 and CBP5 are in random coil and β-sheet conformation, respectively. In addition, the peptides showed different sizes in solution in the absence (∼27 nm, low aggregation) and presence (∼118 nm, high aggregation) of calcium ions. Aragonite crystals with needle-type morphologies were nucleated in the presence of Mg2+ ions in solution. Overall, exploring the activities of such intramineral peptides from CB help to unravel the mechanism of calcium salt deposition in nature.
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Affiliation(s)
- Gomathi Mahadevan
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Rajeev Kungur Brahma
- Department of Biological Sciences, 14 science drive 4, National University of Singapore, Singapore 117543, Singapore
| | - R Manjunatha Kini
- Department of Biological Sciences, 14 science drive 4, National University of Singapore, Singapore 117543, Singapore
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 16 Medical Drive, Singapore 117600, Singapore
| | - Suresh Valiyaveettil
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
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6
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Song X, Hua X, Yang R, Tuo Y, Wang S, Wang J, He P, Luo X. Synergetic effects of initial NH4+ and Ca2+ concentration on the formation vaterite using steamed ammonia liquid waste as a direct carbonation. POWDER TECHNOL 2023. [DOI: 10.1016/j.powtec.2023.118363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
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7
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Gindele MB, Malaszuk KK, Peter C, Gebauer D. On the Binding Mechanisms of Calcium Ions to Polycarboxylates: Effects of Molecular Weight, Side Chain, and Backbone Chemistry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14409-14421. [PMID: 36367750 DOI: 10.1021/acs.langmuir.2c01662] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We experimentally determined the characteristics and Langmuir parameters of the binding of calcium ions to different polycarboxylates. By using potentiometric titrations and isothermal titration calorimetry, the effects of side chain chemistry, pH value, and chain length were systematically investigated using the linear polymers poly(aspartic acid), poly(glutamic acid), and poly(acrylic acid). We demonstrate that for polymers with high polymerization degrees, the binding process is governed by higher-order effects, such as the change of apparent pKa of carboxyl groups, and contributions arising from the whole polymer chain while the chemistry of the monomer unit constituting the polymer plays a subordinate role. In addition, primary binding sites need to be present in the polymer, thus rendering the abundance and sequential arrangement of protonated and deprotonated groups important. The detection of higher-order effects contradicts the assumptions posed by the Langmuir model of noninteracting binding sites and puts a question mark on whether ion binding to polycarboxylates can be described using solely a Langmuir binding model. No single uniform mechanism fits all investigated systems, and the whole polymer chain, including terminal groups, needs to be considered for the interpretation of binding data. Therefore, one needs to be careful when explaining ion binding to polymers solely based on studies on monomers or oligomers.
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Affiliation(s)
- Maxim B Gindele
- Leibniz University Hannover, Institute of Inorganic Chemistry, Callinstr. 9, 30167Hannover, Germany
| | - Krzysztof K Malaszuk
- Leibniz University Hannover, Institute of Inorganic Chemistry, Callinstr. 9, 30167Hannover, Germany
| | - Christine Peter
- Theoretical Chemistry, University of Konstanz, Universitätsstr. 10, 78457Konstanz, Germany
| | - Denis Gebauer
- Leibniz University Hannover, Institute of Inorganic Chemistry, Callinstr. 9, 30167Hannover, Germany
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8
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Different skeletal protein toolkits achieve similar structure and performance in the tropical coral Stylophora pistillata and the temperate Oculina patagonica. Sci Rep 2022; 12:16575. [PMID: 36195656 PMCID: PMC9532382 DOI: 10.1038/s41598-022-20744-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 09/19/2022] [Indexed: 11/08/2022] Open
Abstract
Stony corals (order: Scleractinia) differ in growth form and structure. While stony corals have gained the ability to form their aragonite skeleton once in their evolution, the suite of proteins involved in skeletogenesis is different for different coral species. This led to the conclusion that the organic portion of their skeleton can undergo rapid evolutionary changes by independently evolving new biomineralization-related proteins. Here, we used liquid chromatography-tandem mass spectrometry to sequence skeletogenic proteins extracted from the encrusting temperate coral Oculina patagonica. We compare it to the previously published skeletal proteome of the branching subtropical corals Stylophora pistillata as both are regarded as highly resilient to environmental changes. We further characterized the skeletal organic matrix (OM) composition of both taxa and tested their effects on the mineral formation using a series of overgrowth experiments on calcite seeds. We found that each species utilizes a different set of proteins containing different amino acid compositions and achieve a different morphology modification capacity on calcite overgrowth. Our results further support the hypothesis that the different coral taxa utilize a species-specific protein set comprised of independent gene co-option to construct their own unique organic matrix framework. While the protein set differs between species, the specific predicted roles of the whole set appear to underline similar functional roles. They include assisting in forming the extracellular matrix, nucleation of the mineral and cell signaling. Nevertheless, the different composition might be the reason for the varying organization of the mineral growth in the presence of a particular skeletal OM, ultimately forming their distinct morphologies.
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9
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Mao LB, Meng YF, Meng XS, Yang B, Yang YL, Lu YJ, Yang ZY, Shang LM, Yu SH. Matrix-Directed Mineralization for Bulk Structural Materials. J Am Chem Soc 2022; 144:18175-18194. [PMID: 36162119 DOI: 10.1021/jacs.2c07296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mineral-based bulk structural materials (MBSMs) are known for their long history and extensive range of usage. The inherent brittleness of minerals poses a major problem to the performance of MBSMs. To overcome this problem, design principles have been extracted from natural biominerals, in which the extraordinary mechanical performance is achieved via the hierarchical organization of minerals and organics. Nevertheless, precise and efficient fabrication of MBSMs with bioinspired hierarchical structures under mild conditions has long been a big challenge. This Perspective provides a panoramic view of an emerging fabrication strategy, matrix-directed mineralization, which imitates the in vivo growth of some biominerals. The advantages of the strategy are revealed by comparatively analyzing the conventional fabrication techniques of artificial hierarchically structured MBSMs and the biomineral growth processes. By introducing recent advances, we demonstrate that this strategy can be used to fabricate artificial MBSMs with hierarchical structures. Particular attention is paid to the mass transport and the precursors that are involved in the mineralization process. We hope this Perspective can provide some inspiring viewpoints on the importance of biomimetic mineralization in material fabrication and thereby spur the biomimetic fabrication of high-performance MBSMs.
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Affiliation(s)
- Li-Bo Mao
- Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale; Department of Chemistry, Institute of Biomimetic Materials & Chemistry, University of Science and Technology of China, Hefei 230026, China.,Institute of Advanced Technology, University of Science and Technology of China, Hefei 230026, China.,Anhui Engineering Laboratory of Biomimetic Materials, University of Science and Technology of China, Hefei 230026, China
| | - Yu-Feng Meng
- Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale; Department of Chemistry, Institute of Biomimetic Materials & Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Xiang-Sen Meng
- Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale; Department of Chemistry, Institute of Biomimetic Materials & Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Bo Yang
- Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale; Department of Chemistry, Institute of Biomimetic Materials & Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yu-Lu Yang
- Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale; Department of Chemistry, Institute of Biomimetic Materials & Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yu-Jie Lu
- Institute of Advanced Technology, University of Science and Technology of China, Hefei 230026, China
| | - Zhong-Yuan Yang
- Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale; Department of Chemistry, Institute of Biomimetic Materials & Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Li-Mei Shang
- Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale; Department of Chemistry, Institute of Biomimetic Materials & Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Shu-Hong Yu
- Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale; Department of Chemistry, Institute of Biomimetic Materials & Chemistry, University of Science and Technology of China, Hefei 230026, China.,Institute of Advanced Technology, University of Science and Technology of China, Hefei 230026, China.,Anhui Engineering Laboratory of Biomimetic Materials, University of Science and Technology of China, Hefei 230026, China
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10
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Tarczewska A, Bielak K, Zoglowek A, Sołtys K, Dobryszycki P, Ożyhar A, Różycka M. The Role of Intrinsically Disordered Proteins in Liquid–Liquid Phase Separation during Calcium Carbonate Biomineralization. Biomolecules 2022; 12:biom12091266. [PMID: 36139105 PMCID: PMC9496343 DOI: 10.3390/biom12091266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/06/2022] [Accepted: 09/07/2022] [Indexed: 11/16/2022] Open
Abstract
Some animal organs contain mineralized tissues. These so-called hard tissues are mostly deposits of calcium salts, usually in the form of calcium phosphate or calcium carbonate. Examples of this include fish otoliths and mammalian otoconia, which are found in the inner ear, and they are an essential part of the sensory system that maintains body balance. The composition of ear stones is quite well known, but the role of individual components in the nucleation and growth of these biominerals is enigmatic. It is sure that intrinsically disordered proteins (IDPs) play an important role in this aspect. They have an impact on the shape and size of otoliths. It seems probable that IDPs, with their inherent ability to phase separate, also play a role in nucleation processes. This review discusses the major theories on the mechanisms of biomineral nucleation with a focus on the importance of protein-driven liquid–liquid phase separation (LLPS). It also presents the current understanding of the role of IDPs in the formation of calcium carbonate biominerals and predicts their potential ability to drive LLPS.
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11
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Gilbert PUPA, Bergmann KD, Boekelheide N, Tambutté S, Mass T, Marin F, Adkins JF, Erez J, Gilbert B, Knutson V, Cantine M, Hernández JO, Knoll AH. Biomineralization: Integrating mechanism and evolutionary history. SCIENCE ADVANCES 2022; 8:eabl9653. [PMID: 35263127 PMCID: PMC8906573 DOI: 10.1126/sciadv.abl9653] [Citation(s) in RCA: 60] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Calcium carbonate (CaCO3) biomineralizing organisms have played major roles in the history of life and the global carbon cycle during the past 541 Ma. Both marine diversification and mass extinctions reflect physiological responses to environmental changes through time. An integrated understanding of carbonate biomineralization is necessary to illuminate this evolutionary record and to understand how modern organisms will respond to 21st century global change. Biomineralization evolved independently but convergently across phyla, suggesting a unity of mechanism that transcends biological differences. In this review, we combine CaCO3 skeleton formation mechanisms with constraints from evolutionary history, omics, and a meta-analysis of isotopic data to develop a plausible model for CaCO3 biomineralization applicable to all phyla. The model provides a framework for understanding the environmental sensitivity of marine calcifiers, past mass extinctions, and resilience in 21st century acidifying oceans. Thus, it frames questions about the past, present, and future of CaCO3 biomineralizing organisms.
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Affiliation(s)
- Pupa U. P. A. Gilbert
- Departments of Physics, Chemistry, Geoscience, and Materials Science, University of Wisconsin-Madison, Madison, WI 53706, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Corresponding author. (P.U.P.A.G.); (A.H.K.)
| | - Kristin D. Bergmann
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Nicholas Boekelheide
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sylvie Tambutté
- Centre Scientifique de Monaco, Department of Marine Biology, 98000 Monaco, Principality of Monaco
| | - Tali Mass
- University of Haifa, Marine Biology Department, Mt. Carmel, Haifa 31905, Israel
| | - Frédéric Marin
- Université de Bourgogne–Franche-Comté (UBFC), Laboratoire Biogéosciences, UMR CNRS 6282, Bâtiment des Sciences Gabriel, 21000 Dijon, France
| | - Jess F. Adkins
- Geological and Planetary Sciences, California Institute of Technology, MS 100-23, Pasadena, CA 91125, USA
| | - Jonathan Erez
- The Hebrew University of Jerusalem, Institute of Earth Sciences, Jerusalem 91904, Israel
| | - Benjamin Gilbert
- Energy Geoscience Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Vanessa Knutson
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Marjorie Cantine
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Goethe-Universität Frankfurt, 60438 Frankfurt am Main, Germany
| | - Javier Ortega Hernández
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Andrew H. Knoll
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- Corresponding author. (P.U.P.A.G.); (A.H.K.)
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12
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Drake JL, Varsano N, Mass T. Genetic basis of stony coral biomineralization: History, trends and future prospects. J Struct Biol 2021; 213:107782. [PMID: 34455069 PMCID: PMC7611647 DOI: 10.1016/j.jsb.2021.107782] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/19/2021] [Accepted: 08/21/2021] [Indexed: 12/18/2022]
Abstract
Despite their simple body plan, stony corals (order Scleractinia, phylum Cnidaria) can produce massive and complex exoskeletal structures in shallow, tropical and subtropical regions of Earth's oceans. The species-specific macromorphologies of their aragonite skeletons suggest a highly coordinated biomineralization process that is rooted in their genomes, and which has persisted across major climatic shifts over the past 400 + million years. The mechanisms by which stony corals produce their skeletons has been the subject of interest for at least the last 160 years, and the pace of understanding the process has increased dramatically in the past decade since the sequencing of the first coral genome in 2011. In this review, we detail what is known to date about the genetic basis of the stony coral biomineralization process, with a focus on advances in the last several years as well as ways that physical and chemical tools can be combined with genetics, and then propose next steps forward for the coming decade.
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Affiliation(s)
- Jeana L Drake
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Mt. Carmel, Haifa 3498838, Israel
| | - Neta Varsano
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tali Mass
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Mt. Carmel, Haifa 3498838, Israel; Morris Kahn Marine Research Station, The Leon H. Charney School of Marine Sciences, University of Haifa, Sdot Yam, Israel.
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13
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Drake JL, Benayahu Y, Polishchuk I, Pokroy B, Pinkas I, Mass T. Sclerites of the soft coral Ovabunda macrospiculata (Xeniidae) are predominantly the metastable CaCO 3 polymorph vaterite. Acta Biomater 2021; 135:663-670. [PMID: 34492373 DOI: 10.1016/j.actbio.2021.08.051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 08/24/2021] [Accepted: 08/29/2021] [Indexed: 11/25/2022]
Abstract
Soft corals (Cnidaria, Anthozoa, Octocorallia, Alcyonacea) produce internal sclerites of calcium carbonate previously shown to be composed of calcite, the most stable calcium carbonate polymorph. Here we apply multiple imaging and physical chemistry analyses to extracted and in-vivo sclerites of the abundant Red Sea soft coral, Ovabunda macrospiculata, to detail their mineralogy. We show that this species' sclerites are comprised predominantly of the less stable calcium carbonate polymorph vaterite (> 95%), with much smaller components of aragonite and calcite. Use of this mineral, which is typically considered to be metastable, by these soft corals has implications for how it is formed as well as how it will persist during the anticipated anthropogenic climate change in the coming decades. This first documentation of vaterite dominating the mineral composition of O. macrospiculata sclerites is likely just the beginning of establishing its presence in other soft corals. STATEMENT OF SIGNIFICANCE: Vaterite is typically considered to be a metastable polymorph of calcium carbonate. While calcium carbonate structures formed within the tissues of octocorals (phylum Cnidaria), have previously been reported to be composed of the more stable polymorphs aragonite and calcite, we observed that vaterite dominates the mineralogy of sclerites of Ovabunda macrospiculata from the Red Sea. Based on electron microscopy, Raman spectroscopy, and X-ray diffraction analysis, vaterite appears to be the dominant polymorph in sclerites both in the tissue and after extraction and preservation. Although this is the first documentation of vaterite in soft coral sclerites, it likely will be found in sclerites of other related taxa as well.
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14
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Mahadevan G, Ruifan Q, Hian Jane YH, Valiyaveettil S. Effect of Polymer Nano- and Microparticles on Calcium Carbonate Crystallization. ACS OMEGA 2021; 6:20522-20529. [PMID: 34395998 PMCID: PMC8359134 DOI: 10.1021/acsomega.1c02564] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 06/16/2021] [Indexed: 05/29/2023]
Abstract
Molecular and macromolecular templates are known to affect the shape, size, and polymorph selectivity on the biomineralization of calcium carbonate (CaCO3). Micro- and nanoparticles of common polymers present in the environment are beginning to show toxicity in living organisms. In this study, the role of plastic nanoparticles in the biomineralization of CaCO3 is explored to understand the ecological impact of plastic pollution. As a model study, luminescent poly(methyl methacrylate) nanoparticles (PMMA-NPs) were prepared using the nanoprecipitation method, fully characterized, and used for the mineralization experiments to understand their influence on nucleation, morphology, and polymorph selectivity of CaCO3 crystals. The PMMA-NPs induced calcite crystal nucleation with spherical morphologies at high concentrations. Microplastic particles collected from a commercial face scrub were also used for CaCO3 nucleation to observe the nucleation of calcite crystals on the particle surface. Microscopic, spectroscopic, and X-ray diffraction data were used to characterize and identify the nucleated crystals. The data presented in this paper add more information on the impact of microplastics on the marine environment.
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Affiliation(s)
- Gomathi Mahadevan
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore
| | - Qiu Ruifan
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore
| | - Yap Hui Hian Jane
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore
| | - Suresh Valiyaveettil
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore
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15
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Conci N, Lehmann M, Vargas S, Wörheide G. Comparative Proteomics of Octocoral and Scleractinian Skeletomes and the Evolution of Coral Calcification. Genome Biol Evol 2021; 12:1623-1635. [PMID: 32761183 PMCID: PMC7533068 DOI: 10.1093/gbe/evaa162] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2020] [Indexed: 12/23/2022] Open
Abstract
Corals are the ecosystem engineers of coral reefs, one of the most biodiverse marine ecosystems. The ability of corals to form reefs depends on the precipitation of calcium carbonate (CaCO3) under biological control. However, several mechanisms underlying coral biomineralization remain elusive, for example, whether corals employ different molecular machineries to deposit different CaCO3 polymorphs (i.e., aragonite or calcite). Here, we used tandem mass spectrometry (MS/MS) to compare the proteins occluded in the skeleton of three octocoral and one scleractinian species: Tubipora musica and Sinularia cf. cruciata (calcite sclerites), the blue coral Heliopora coerulea (aragonitic skeleton), and the scleractinian aragonitic Montipora digitata. Reciprocal Blast analysis revealed extremely low overlap between aragonitic and calcitic species, while a core set of proteins is shared between octocorals producing calcite sclerites. However, the carbonic anhydrase CruCA4 is present in the skeletons of both polymorphs. Phylogenetic analysis highlighted several possible instances of protein co-option in octocorals. These include acidic proteins and scleritin, which appear to have been secondarily recruited for calcification and likely derive from proteins playing different functions. Similarities between octocorals and scleractinians included presence of a galaxin-related protein, carbonic anhydrases, and one hephaestin-like protein. Although the first two appear to have been independently recruited, the third appear to share a common origin. This work represents the first attempt to identify and compare proteins associated with coral skeleton polymorph diversity, providing several new research targets and enabling both future functional and evolutionary studies aimed at elucidating the origin and evolution of coral biomineralization.
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Affiliation(s)
- Nicola Conci
- Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universität München, München, Germany
| | - Martin Lehmann
- Department of Biology I-Botany, Biozentrum der LMU München, Planegg-Martinsried, Germany
| | - Sergio Vargas
- Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universität München, München, Germany
| | - Gert Wörheide
- Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universität München, München, Germany.,SNSB - Bayerische Staatssammlung für Paläontologie und Geologie, Munich, Germany.,GeoBio-Center LMU, Ludwig-Maximilians-Universität München, München, Germany
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Hu H, Liang F, Zhu H, Zhang X, Cui K, Deb H, Zhang Y. Formation and Phase Selection of CaCO
3
in the Intervention of Lignin Monomer Model Compounds. CRYSTAL RESEARCH AND TECHNOLOGY 2021. [DOI: 10.1002/crat.202000187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Huifeng Hu
- Key Laboratory of Advanced Textile Materials and Manufacturing Technology of the Ministry of Education, College of Textiles Science and Engineering Zhejiang Sci‐Tech University Hangzhou 310018 China
| | - Fugen Liang
- Zhejiang Transfar Whyyon Chemical Co., Ltd. Hangzhou 311231 China
| | - Haidong Zhu
- Hangzhou Vocational and Technical College Hangzhou 310018 China
| | - Xiumei Zhang
- Key Laboratory of Advanced Textile Materials and Manufacturing Technology of the Ministry of Education, College of Textiles Science and Engineering Zhejiang Sci‐Tech University Hangzhou 310018 China
| | - Kecong Cui
- Key Laboratory of Advanced Textile Materials and Manufacturing Technology of the Ministry of Education, College of Textiles Science and Engineering Zhejiang Sci‐Tech University Hangzhou 310018 China
| | - Hridam Deb
- Key Laboratory of Advanced Textile Materials and Manufacturing Technology of the Ministry of Education, College of Textiles Science and Engineering Zhejiang Sci‐Tech University Hangzhou 310018 China
| | - Yong Zhang
- Key Laboratory of Advanced Textile Materials and Manufacturing Technology of the Ministry of Education, College of Textiles Science and Engineering Zhejiang Sci‐Tech University Hangzhou 310018 China
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Mummadisetti MP, Drake JL, Falkowski PG. The spatial network of skeletal proteins in a stony coral. J R Soc Interface 2021; 18:20200859. [PMID: 33622149 PMCID: PMC8086859 DOI: 10.1098/rsif.2020.0859] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Coral skeletons are materials composed of inorganic aragonitic fibres and organic molecules including proteins, sugars and lipids that are highly organized to form a solid biomaterial upon which the animals live. The skeleton contains tens of proteins, all of which are encoded in the animal genome and secreted during the biomineralization process. While recent advances are revealing the functions and evolutionary history of some of these proteins, how they are spatially arranged in the skeleton is unknown. Using a combination of chemical cross-linking and high-resolution tandem mass spectrometry, we identify, for the first time, the spatial interactions of the proteins embedded within the skeleton of the stony coral Stylophora pistillata. Our subsequent network analysis revealed that several coral acid-rich proteins are invariably associated with carbonic anhydrase(s), alpha-collagen, cadherins and other calcium-binding proteins. These spatial arrangements clearly show that protein-protein interactions in coral skeletons are highly coordinated and are key to understanding the formation and persistence of coral skeletons through time.
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Affiliation(s)
- Manjula P Mummadisetti
- Environmental Biophysics and Molecular Biology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Rd, New Brunswick, NJ 08901, USA
| | - Jeana L Drake
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, 595 Charles E. Young Drive East, Los Angeles, CA 90095, USA.,Department of Marine Biology, University of Haifa, 199 Aba Khoushy Avenue, Mount Carmel, Haifa 2498838, Israel
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Biology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Rd, New Brunswick, NJ 08901, USA.,Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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18
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Conci N, Vargas S, Wörheide G. The Biology and Evolution of Calcite and Aragonite Mineralization in Octocorallia. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.623774] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Octocorallia (class Anthozoa, phylum Cnidaria) is a group of calcifying corals displaying a wide diversity of mineral skeletons. This includes skeletal structures composed of different calcium carbonate polymorphs (aragonite and calcite). This represents a unique feature among anthozoans, as scleractinian corals (subclass Hexacorallia), main reef builders and focus of biomineralization research, are all characterized by an aragonite exoskeleton. From an evolutionary perspective, the presence of aragonitic skeletons in Octocorallia is puzzling as it is observed in very few species and has apparently originated during a Calcite sea (i.e., time interval characterized by calcite-inducing seawater conditions). Despite this, octocorals have been systematically overlooked in biomineralization studies. Here we review what is known about octocoral biomineralization, focusing on the evolutionary and biological processes that underlie calcite and aragonite formation. Although differences in research focus between octocorals and scleractinians are often mentioned, we highlight how strong variability also exists between different octocoral groups. Different main aspects of octocoral biomineralization have been in fact studied in a small set of species, including the (calcitic) gorgonian Leptogorgia virgulata and/or the precious coral Corallium rubrum. These include descriptions of calcifying cells (scleroblasts), calcium transport and chemistry of the calcification fluids. With the exception of few histological observations, no information on these features is available for aragonitic octocorals. Availability of sequencing data is also heterogeneous between groups, with no transcriptome or genome available, for instance, for the clade Calcaxonia. Although calcite represents by far the most common polymorph deposited by octocorals, we argue that studying aragonite-forming could provide insight on octocoral, and more generally anthozoan, biomineralization. First and foremost it would allow to compare calcification processes between octocoral groups, highlighting homologies and differences. Secondly, similarities (exoskeleton) between Heliopora and scleractinian skeletons, would provide further insight on which biomineralization features are driven by skeleton characteristics (shared by scleractinians and aragonitic octocorals) and those driven by taxonomy (shared by octocorals regardless of skeleton polymorph). Including the diversity of anthozoan mineralization strategies into biomineralization studies remains thus essential to comprehensively study how skeletons form and evolved within this ecologically important group of marine animals.
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Zaquin T, Malik A, Drake JL, Putnam HM, Mass T. Evolution of Protein-Mediated Biomineralization in Scleractinian Corals. Front Genet 2021; 12:618517. [PMID: 33633782 PMCID: PMC7902050 DOI: 10.3389/fgene.2021.618517] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 01/08/2021] [Indexed: 12/19/2022] Open
Abstract
While recent strides have been made in understanding the biological process by which stony corals calcify, much remains to be revealed, including the ubiquity across taxa of specific biomolecules involved. Several proteins associated with this process have been identified through proteomic profiling of the skeletal organic matrix (SOM) extracted from three scleractinian species. However, the evolutionary history of this putative “biomineralization toolkit,” including the appearance of these proteins’ throughout metazoan evolution, remains to be resolved. Here we used a phylogenetic approach to examine the evolution of the known scleractinians’ SOM proteins across the Metazoa. Our analysis reveals an evolutionary process dominated by the co-option of genes that originated before the cnidarian diversification. Each one of the three species appears to express a unique set of the more ancient genes, representing the independent co-option of SOM proteins, as well as a substantial proportion of proteins that evolved independently. In addition, in some instances, the different species expressed multiple orthologous proteins sharing the same evolutionary history. Furthermore, the non-random clustering of multiple SOM proteins within scleractinian-specific branches suggests the conservation of protein function between distinct species for what we posit is part of the scleractinian “core biomineralization toolkit.” This “core set” contains proteins that are likely fundamental to the scleractinian biomineralization mechanism. From this analysis, we infer that the scleractinians’ ability to calcify was achieved primarily through multiple lineage-specific protein expansions, which resulted in a new functional role that was not present in the parent gene.
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Affiliation(s)
- Tal Zaquin
- Department of Marine Biology, The Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Assaf Malik
- Department of Marine Biology, The Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Jeana L Drake
- Department of Marine Biology, The Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Hollie M Putnam
- Department of Biological Sciences, University of Rhode Island, Kingston, RI, United States
| | - Tali Mass
- Department of Marine Biology, The Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
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20
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Sun CY, Gránásy L, Stifler CA, Zaquin T, Chopdekar RV, Tamura N, Weaver JC, Zhang JAY, Goffredo S, Falini G, Marcus MA, Pusztai T, Schoeppler V, Mass T, Gilbert PUPA. Crystal nucleation and growth of spherulites demonstrated by coral skeletons and phase-field simulations. Acta Biomater 2021; 120:277-292. [PMID: 32590171 PMCID: PMC7116570 DOI: 10.1016/j.actbio.2020.06.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/16/2020] [Accepted: 06/16/2020] [Indexed: 01/07/2023]
Abstract
Spherulites are radial distributions of acicular crystals, common in biogenic, geologic, and synthetic systems, yet exactly how spherulitic crystals nucleate and grow is still poorly understood. To investigate these processes in more detail, we chose scleractinian corals as a model system, because they are well known to form their skeletons from aragonite (CaCO3) spherulites, and because a comparative study of crystal structures across coral species has not been performed previously. We observed that all 12 diverse coral species analyzed here exhibit plumose spherulites in their skeletons, with well-defined centers of calcification (CoCs), and crystalline fibers radiating from them. In 7 of the 12 species, we observed a skeletal structural motif not observed previously: randomly oriented, equant crystals, which we termed "sprinkles". In Acropora pharaonis, these sprinkles are localized at the CoCs, while in 6 other species, sprinkles are either layered at the growth front (GF) of the spherulites, or randomly distributed. At the nano- and micro-scale, coral skeletons fill space as much as single crystals of aragonite. Based on these observations, we tentatively propose a spherulite formation mechanism in which growth front nucleation (GFN) of randomly oriented sprinkles, competition for space, and coarsening produce spherulites, rather than the previously assumed slightly misoriented nucleations termed "non-crystallographic branching". Phase-field simulations support this mechanism, and, using a minimal set of thermodynamic parameters, are able to reproduce all of the microstructural variation observed experimentally in all of the investigated coral skeletons. Beyond coral skeletons, other spherulitic systems, from aspirin to semicrystalline polymers and chocolate, may also form according to the mechanism for spherulite formation proposed here. STATEMENT OF SIGNIFICANCE: Understanding the fundamental mechanisms of spherulite nucleation and growth has broad ranging applications in the fields of metallurgy, polymers, food science, and pharmaceutical production. Using the skeletons of reef-building corals as a model system for investigating these processes, we propose a new spherulite growth mechanism that can not only explain the micro-structural diversity observed in distantly related coral species, but may point to a universal growth mechanism in a wide range of biologically and technologically relevant spherulitic materials systems.
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Affiliation(s)
- Chang-Yu Sun
- Department of Physics, University of Wisconsin, Madison, WI 53706, USA; Materials Science Program, University of Wisconsin, Madison, WI 53706, USA
| | - László Gránásy
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, PO Box 49, 1525 Budapest, Hungary
| | - Cayla A Stifler
- Department of Physics, University of Wisconsin, Madison, WI 53706, USA
| | - Tal Zaquin
- University of Haifa, Marine Biology Department, Mt. Carmel, Haifa 31905, Israel
| | - Rajesh V Chopdekar
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Nobumichi Tamura
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - James C Weaver
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - Jun A Y Zhang
- Department of Physics, University of Wisconsin, Madison, WI 53706, USA
| | - Stefano Goffredo
- Marine Science Group, Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Selmi 3, I-40126 Bologna, Italy; Fano Marine Center, The Inter-Institute Center for Research on Marine Biodiversity, Resources and Biotechnologies, viale Adriatico 1/N, 61032 Fano, Pesaro Urbino, Italy
| | - Giuseppe Falini
- Department of Chemistry "Giacomo Ciamician", Alma Mater Studiorum - University of Bologna, Via Selmi 2, 40126 Bologna, Italy; Fano Marine Center, The Inter-Institute Center for Research on Marine Biodiversity, Resources and Biotechnologies, viale Adriatico 1/N, 61032 Fano, Pesaro Urbino, Italy
| | - Matthew A Marcus
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Tamás Pusztai
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, PO Box 49, 1525 Budapest, Hungary
| | - Vanessa Schoeppler
- B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, 01307 Dresden, Germany
| | - Tali Mass
- University of Haifa, Marine Biology Department, Mt. Carmel, Haifa 31905, Israel
| | - Pupa U P A Gilbert
- Department of Physics, University of Wisconsin, Madison, WI 53706, USA; Departments of Chemistry, Geoscience, Materials Science, University of Wisconsin, Madison, WI 53706, USA.
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