1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Drake JL, Mass T, Stolarski J, Von Euw S, van de Schootbrugge B, Falkowski PG. How corals made rocks through the ages. GLOBAL CHANGE BIOLOGY 2020; 26:31-53. [PMID: 31696576 PMCID: PMC6942544 DOI: 10.1111/gcb.14912] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 10/28/2019] [Accepted: 10/30/2019] [Indexed: 05/03/2023]
Abstract
Hard, or stony, corals make rocks that can, on geological time scales, lead to the formation of massive reefs in shallow tropical and subtropical seas. In both historical and contemporary oceans, reef-building corals retain information about the marine environment in their skeletons, which is an organic-inorganic composite material. The elemental and isotopic composition of their skeletons is frequently used to reconstruct the environmental history of Earth's oceans over time, including temperature, pH, and salinity. Interpretation of this information requires knowledge of how the organisms formed their skeletons. The basic mechanism of formation of calcium carbonate skeleton in stony corals has been studied for decades. While some researchers consider coral skeletons as mainly passive recorders of ocean conditions, it has become increasingly clear that biological processes play key roles in the biomineralization mechanism. Understanding the role of the animal in living stony coral biomineralization and how it evolved has profound implications for interpreting environmental signatures in fossil corals to understand past ocean conditions. Here we review historical hypotheses and discuss the present understanding of how corals evolved and how their skeletons changed over geological time. We specifically explain how biological processes, particularly those occurring at the subcellular level, critically control the formation of calcium carbonate structures. We examine the different models that address the current debate including the tissue-skeleton interface, skeletal organic matrix, and biomineralization pathways. Finally, we consider how understanding the biological control of coral biomineralization is critical to informing future models of coral vulnerability to inevitable global change, particularly increasing ocean acidification.
Collapse
Affiliation(s)
- Jeana L Drake
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - Tali Mass
- Department of Marine Biology, The Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | | | - Stanislas Von Euw
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | | | - Paul G Falkowski
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, USA
| |
Collapse
|
3
|
Ohno Y, Iguchi A, Shinzato C, Gushi M, Inoue M, Suzuki A, Sakai K, Nakamura T. Calcification process dynamics in coral primary polyps as observed using a calcein incubation method. Biochem Biophys Rep 2017; 9:289-294. [PMID: 29114586 PMCID: PMC5627507 DOI: 10.1016/j.bbrep.2017.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Revised: 11/13/2016] [Accepted: 01/23/2017] [Indexed: 11/29/2022] Open
Abstract
Calcification processes are largely unknown in scleractinian corals. In this study, live confocal imaging was used to elucidate the spatiotemporal dynamics of the calcification process in aposymbiotic primary polyps of the coral species Acropora digitifera. The fluorophore calcein was used as a calcium deposition marker and a visible indicator of extracellular fluid distribution at the tissue-skeleton interface (subcalicoblastic medium, SCM) in primary polyp tissues. Under continuous incubation in calcein-containing seawater, initial crystallization and skeletal growth were visualized among the calicoblastic cells in live primary polyp tissues. Additionally, the distribution of calcein-stained SCM and contraction movements of the pockets of SCM were captured at intervals of a few minutes. Our experimental system provided several new insights into coral calcification, particularly as a first step in monitoring the relationship between cellular dynamics and calcification in vivo. Our study suggests that coral calcification initiates at intercellular spaces, a finding that may contribute to the general understanding of coral calcification processes. Coral calcification dynamics were observed by using aposymbiotic primary polyps. CaCO3 deposits during skeletal formation were visualized by calcein fluorescence labeling and time-lapse confocal microscopy. Periodic pulsing activity of the pockets of subcalicoblastic medium (SCM) was detected.
Collapse
Affiliation(s)
- Yoshikazu Ohno
- Marine and Environmental Sciences Course, Graduate School of Engineering and Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan
| | - Akira Iguchi
- Department of Bioresources Engineering, National Institute of Technology, Okinawa College, 905 Henoko, Nago, Okinawa 905-2192, Japan
| | - Chuya Shinzato
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Mikako Gushi
- Department of Bioresources Engineering, National Institute of Technology, Okinawa College, 905 Henoko, Nago, Okinawa 905-2192, Japan
| | - Mayuri Inoue
- Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan
| | - Atsushi Suzuki
- Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan
| | - Kazuhiko Sakai
- Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, Motobu, Okinawa 905-0227, Japan
| | - Takashi Nakamura
- Marine and Environmental Sciences Course, Graduate School of Engineering and Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan.,Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, Motobu, Okinawa 905-0227, Japan.,Japan Science and Technology Agency (JST)/Japan International Cooperation Agency (JICA) SATREPS, Tokyo, Japan
| |
Collapse
|
4
|
Gilis M, Meibom A, Domart-Coulon I, Grauby O, Stolarski J, Baronnet A. Biomineralization in newly settled recruits of the scleractinian coral Pocillopora damicornis. J Morphol 2014; 275:1349-65. [PMID: 24966116 DOI: 10.1002/jmor.20307] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 05/26/2014] [Accepted: 06/03/2014] [Indexed: 01/26/2023]
Abstract
Calcium carbonate biomineralization of scleractinian coral recruits is fundamental to the construction of reefs and their survival under stress from global and local environmental change. Establishing a baseline for how normal, healthy coral recruits initiate skeletal formation is, therefore, warranted. Here, we present a thorough, multiscale, microscopic and spectroscopic investigation of skeletal elements deposited by Pocillopora damicornis recruits, from 12 h to 22 days after settlement in aquarium on a flat substrate. Six growth stages are defined, primarily based on appearance and morphology of successively deposited skeletal structures, with the following average formation time-scales: A (<24 h), B (24-36 h), C (36-48 h), D (48-72 h), E (72-96 h), and F (>10 days). Raman and energy dispersive X-ray spectroscopy indicate the presence of calcite among the earliest components of the basal plate, which consist of micrometer-sized, rod-shaped crystals with rhomboidal habit. All later CaCO3 skeletal structures are composed exclusively of aragonite. High-resolution scanning electron microscopy reveals that, externally, all CaCO3 deposits consist of <100 nm granular units. Fusiform, dumbbell-like, and semispherulitic structures, 25-35 µm in longest dimension, occur only during the earliest stages (Stages A-C), with morphologies similar to structures formed abiotically or induced by organics in in vitro carbonate crystallization experiments. All other skeletal structures of the basal plate are composed of vertically extending lamellar bundles of granules. From Stage D, straight fibrils, 40-45 nm in width and presumably of organic composition, form bridges between these aragonitic bundles emerging from the growing front of fusing skeletal structures. Our results show a clear evolution in the coral polyp biomineralization process as the carbonate structures develop toward those characterizing the adult skeleton.
Collapse
Affiliation(s)
- Melany Gilis
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1009, Lausanne, Switzerland; Center for Advanced Surface Analysis, Institute of Earth Sciences, University of Lausanne, CH-1009, Lausanne, Switzerland
| | | | | | | | | | | |
Collapse
|
5
|
Ramos-Silva P, Kaandorp J, Herbst F, Plasseraud L, Alcaraz G, Stern C, Corneillat M, Guichard N, Durlet C, Luquet G, Marin F. The skeleton of the staghorn coral Acropora millepora: molecular and structural characterization. PLoS One 2014; 9:e97454. [PMID: 24893046 PMCID: PMC4043741 DOI: 10.1371/journal.pone.0097454] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Accepted: 04/19/2014] [Indexed: 01/28/2023] Open
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.
Collapse
Affiliation(s)
- Paula Ramos-Silva
- UMR 6282 Biogéosciences, Université de Bourgogne, Dijon, France
- Section Computational Science, Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands
| | - Jaap Kaandorp
- Section Computational Science, Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands
- * E-mail: (JK); (FM)
| | | | - Laurent Plasseraud
- UMR 6302, Institut de Chimie Moléculaire, Université de Bourgogne, Dijon, France
| | - Gérard Alcaraz
- UMR 1347, Agroécologie INRA, Université de Bourgogne, AgroSup Dijon, Pôle Mécanisme & Gestion Interactions Plantes Micro-organismes, ERL 6300, Dijon, France
| | - Christine Stern
- UMR 6302, Institut de Chimie Moléculaire, Université de Bourgogne, Dijon, France
| | - Marion Corneillat
- UMR 1347, Agroécologie INRA, Université de Bourgogne, AgroSup Dijon, Pôle Mécanisme & Gestion Interactions Plantes Micro-organismes, ERL 6300, Dijon, France
| | | | | | - Gilles Luquet
- UMR 6282 Biogéosciences, Université de Bourgogne, Dijon, France
- UMR 7245, Muséum National d'Histoire Naturelle, Paris, France
| | - Frédéric Marin
- UMR 6282 Biogéosciences, Université de Bourgogne, Dijon, France
- * E-mail: (JK); (FM)
| |
Collapse
|
6
|
Shirai K, Sowa K, Watanabe T, Sano Y, Nakamura T, Clode P. Visualization of sub-daily skeletal growth patterns in massive Porites corals grown in Sr-enriched seawater. J Struct Biol 2012; 180:47-56. [PMID: 22683766 DOI: 10.1016/j.jsb.2012.05.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 05/22/2012] [Accepted: 05/23/2012] [Indexed: 11/28/2022]
Abstract
We performed high resolution marking experiments using seawater with elevated Sr concentration to investigate the timing and ultrastructure of skeletal deposition by massive Porites australiensis corals. Corals were cultured in seawater enriched with Sr during day-time only, night-time only or for one full-day. Cross sections of skeletal material were prepared and the Sr incorporated into the newly deposited skeleton analyzed by electron probe microanalysis. These regions of Sr incorporation were then correlated with skeletal ultrastructure. Massive Porites coral skeletons are composed of two types of microstructural elements - the "centers of calcification" and the surrounding fibrous structural region. Within the fibrous structural region, alternative patterns of etch-sensitive growth lines and an etch-resistant fibrous layer were observed. In the full-day samples, high-Sr bands extended across both growth lines and fibrous layers. In day-time samples, high-Sr regions corresponded to the fibrous layer, while in the night-time samples high-Sr regions were associated with an outermost growth line. These distinct growth patterns suggest a daily growth pattern associated with the fibrous region of massive P. australiensis corals, where a pair of narrow growth lines and a larger fibrous layer is seen as a daily growth region.
Collapse
Affiliation(s)
- Kotaro Shirai
- Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan.
| | | | | | | | | | | |
Collapse
|
7
|
Construction and nanomechanical properties of the exoskeleton of the barnacle, Amphibalanus reticulatus. J Struct Biol 2011; 176:360-9. [PMID: 21911065 DOI: 10.1016/j.jsb.2011.08.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 08/19/2011] [Accepted: 08/29/2011] [Indexed: 11/24/2022]
Abstract
Barnacles are some of the major inhabitants of intertidal zones and have calcite-based exoskeleton to anchor and armor their tissues. Structural characterization studies of the specie Ambhibalanus reticulatus were performed to understand the construction of the exoskeleton which forms a light-weight yet stiff structure. The parietal shell is constructed of six compartments to yield a truncated cone geometry, which is neatly fixed onto the basal shell that attaches the organism to the substrate surface. The connections among the different compartments happen through sutured edges and also have chemical interlocking to make the junctions impermeable. Also, the shell parts are furnished with hollow channels reducing the overall mass of the construction. The structure and functions of different parts of the exoskeleton are identified and outlined. Finally, the mechanical properties such as modulus, hardness and fracture toughness of the exoskeleton obtained by indentation techniques are discussed.
Collapse
|
8
|
Benzerara K, Menguy N, Obst M, Stolarski J, Mazur M, Tylisczak T, Brown GE, Meibom A. Study of the crystallographic architecture of corals at the nanoscale by scanning transmission X-ray microscopy and transmission electron microscopy. Ultramicroscopy 2011; 111:1268-75. [PMID: 21864767 DOI: 10.1016/j.ultramic.2011.03.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Revised: 03/26/2011] [Accepted: 03/31/2011] [Indexed: 10/18/2022]
Abstract
We have investigated the nanotexture and crystallographic orientation of aragonite in a coral skeleton using synchrotron-based scanning transmission X-ray microscopy (STXM) and transmission electron microscopy (TEM). Polarization-dependent STXM imaging at 40-nm spatial resolution was used to obtain an orientation map of the c-axis of aragonite on a focused ion beam milled ultrathin section of a Porites coral. This imaging showed that one of the basic units of coral skeletons, referred to as the center of calcification (COC), consists of a cluster of 100-nm aragonite globules crystallographically aligned over several micrometers with a fan-like distribution and with the properties of single crystals at the mesoscale. The remainder of the skeleton consists of aragonite single-crystal fibers in crystallographic continuity with the nanoglobules comprising the COC. Our observation provides information on the nm-scale processes that led to biomineral formation in this sample. Importantly, the present study illustrates how the methodology described here, which combines HRTEM and polarization-dependent synchrotron-based STXM imaging, offers an interesting new approach for investigating biomineralizing systems at the nm-scale.
Collapse
Affiliation(s)
- Karim Benzerara
- Institut de Minéralogie et de Physique des Milieux Condensés, UMR 7590, CNRS, Universités Paris 6 & IPGP. 4 Place Jussieu, 75005 Paris, France.
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Sethmann I, Helbig U, Wörheide G. Octocoral sclerite ultrastructures and experimental approach to underlying biomineralisation principles. CrystEngComm 2007. [DOI: 10.1039/b711068e] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
10
|
Raz-Bahat M, Erez J, Rinkevich B. In vivo light-microscopic documentation for primary calcification processes in the hermatypic coral Stylophora pistillata. Cell Tissue Res 2006; 325:361-8. [PMID: 16568301 DOI: 10.1007/s00441-006-0182-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Accepted: 02/01/2006] [Indexed: 10/24/2022]
Abstract
Skeletogenesis in the hermatypic coral Stylophora pistillata was studied by using the lateral skeleton preparative (LSP) assay, viz., a coral nubbin attached to a glass coverslip glued to the bottom of a Petri dish. Observations on tissue and skeletal growth were made by polarized microscopy and by using vital staining. The horizontal distal tissue edges developed thin transparent extensions of ectodermal and calicoblastic layers only. Four stages (I-IV) of skeletogenesis were observed at these edges, underneath the newly developed tissue. In stage I, a thin clear layer of coral tissue advanced 3-40 microm beyond the existing LSP peripheral zone, revealing no sign of spiculae deposition. At stage II, primary fusiform crystals (1 microm each) were deposited, forming a primary discontinuous skeletal front 5-30 microm away from the previously deposited skeleton. During stage III, needle-like crystals appeared, covering the primary fusiform crystals. Stage IV involved further lengthening of the needle-like crystals, a process that resulted in occlusion of the spaces between adjacent crystals. Calcification stages I-III developed within hours, whereas stage IV was completed in several days to weeks. Two basic skeletal structures, "scattered" and "laminar" skeletons, were formed, integrating the growth patterns of the needle-like crystals. High variation was recorded in the expression of the four calcification stages, either between different locations along a single LSP or between different preparations observed at the same diurnal time. All four skeletogenesis stages took place during both day and night periods, indicating that an intrinsic process controls S. pistillata calcification.
Collapse
Affiliation(s)
- Michal Raz-Bahat
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, PO Box 8030, Haifa 31080, Israel
| | | | | |
Collapse
|
11
|
Clode PL, Marshall AT. Variation in skeletal microstructure of the coral Galaxea fascicularis: effects of an aquarium environment and preparatory techniques. THE BIOLOGICAL BULLETIN 2003; 204:138-145. [PMID: 12700144 DOI: 10.2307/1543549] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
To compare the crystalline microstructure of exsert septa, polyps of the scleractinian coral Galaxea fascicularis were sampled from shallow reef flat colonies, from colonies living at a depth of 9 m, and from colonies kept in a closed-circuit aquarium. Septal crystal structure and orientation was markedly different between corals in the field and in aquaria. In samples collected from deep water, acicular crystals were composed of conglomerates of finer crystals, and skeletal filling was considerably reduced when compared with samples collected from shallow water. Comparisons were also made between septa prepared in sodium hypochlorite (commercial bleach), sodium hydroxide (NaOH), hydrogen peroxide (H(2)O(2)), and distilled water (dH(2)O). Commercial bleach was the most effective solvent for tissue dissolution in investigations of skeletal structure. Samples prepared in NaOH commonly displayed crystalline artefacts, while the use of dH(2)O and H(2)O(2) was labor intensive and often resulted in unclean preparations. Fusiform crystals were seen only on G. fascicularis septa prepared in bleach and on Acropora formosa axial corallites prepared in either bleach or dH(2)O. We suggest that the mechanical agitation and additional washing necessary for samples prepared in dH(2)O, NaOH, or H(2)O(2) resulted in the loss of fusiform crystals from these preparations.
Collapse
Affiliation(s)
- Peta L Clode
- Department of Zoology, La Trobe University, Melbourne, Victoria 3086, Australia
| | | |
Collapse
|