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| Titel |
A unique skeletal microstructure of the deep-sea micrabaciid scleractinian corals |
| VerfasserIn |
Katarzyna Janiszewska, Jaroslaw Stolarski, Karim Benzerara, Anders Meibom, Maciej Mazur, Marcelo Kitahara, Stephen D. Cairns |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040013
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| Zusammenfassung |
| Structural and biogeochemical properties of the skeleton of many invertebrates rely on
organic matrix-mediated biomineralization processes. Organic matrices, composed of
complex assemblages of macromolecules (proteins, polysaccharides), may control
nucleation, spatial delineation and organization of basic microstructural units. Biologically
controlled mineralization is also suggested for the scleractinian corals whose different,
molecularly recognized clades are supported by distinct types of skeletal microstructures.
Main differences in scleractinian coral skeletal microstructures suggested so far consist in (1)
varying spatial relationships between Rapid Accretion Deposits (RAD, “centers of
calcification”) and thickening deposits (TD, “fibers”), and (2) varying arrangements of
biomineral fibers into higher order structures (e.g., bundles of fibers perpendicular to skeletal
surfaces in some “caryophylliid” corals vs. scale-like units with fibers parallel to the
surface in acroporiids). However, a common feature of biomineral fibers in corals
described thus far was their similar crystallographic arrangement within larger
meso-scale structures (bundles of fibers) and continuity between successive growth
layers.
Herein we show that representatives of the deep-sea scleractinian family Micrabaciidae
(genera: Letepsammia, Rhombopsammia, Stephanophyllia, Leptopenus) have thickening
deposits composed of irregular meshwork of short (1-2 μm) and extremely thin (ca.
100-300 nm) fibers organized into small bundles (ca. 1-2 μm thick). Longer axes
of fibers are aligned within individual bundles that, in turn, show rather irregular
arrangement on the growing surfaces and within the skeleton (irregular criss-cross
pattern). In contrast to other scleractinians (including deep-water “caryophylliids”,
fungiacyathids, and anthemiphyllids sympatric with micrabaciids), growth layers are not
distinct. Also the regions of rapid accretion and thickening deposits are not clearly
separated at the meso-scale. However, AFM and FESEM observations of RAD show
nanogranular units (ca. 30-100 nm in diameter) typical of fast growing skeletal
regions.
Unique microstructural organization of the micrabaciid skeleton supports their
monophyletic status (reinforced by macromorphological and molecular data), and points to a
diversity of organic matrix-mediated biomineralization strategies in Scleractinia. |
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