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| Titel |
The Environment Recording Unit in coral skeletons – a synthesis of structural and chemical evidences for a biochemically driven, stepping-growth process in fibres |
| VerfasserIn |
J. P. Cuif, Y. Dauphin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 2, no. 1 ; Nr. 2, no. 1 (2005-02-25), S.61-73 |
| Datensatznummer |
250000379
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| Publikation (Nr.) |
 copernicus.org/bg-2-61-2005.pdf |
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| Zusammenfassung |
This paper gathers a series of structural and biochemical in situ characterizations
carried out to improve our knowledge of the fine scale growth patterns of
fibres in coral skeletons. The resulting data show a clear correspondence
between the mineral subunits of fibres and the spatial distribution of
organic macromolecules. New observations using atomic force microscope
confirm the close relationship between mineral and organic phases at the
nanometre scale.
Synthesis of these data results in a significant change in our concept of
the mineralization process in coral skeletons. In contrast to the usual view
of an aggregate of purely mineral units independently growing by simple
chemical precipitation, coral fibres appear to be fully controlled
structures. Their growth process is based on cyclic secretion of
mineralizing compounds by the polyp basal ectoderm. These biochemical
components of the coral fibres, in which sulfated acidic proteoglycans
probably play a major role, are repeatedly produced (proteoglycans are those
glycoproteins whose carbohydrate moieties consist of long unbranched chains
of sulfated amino sugars). This results in a stepping growth mode of fibres
and a layered global organization of coral skeletons.
Therefore, in contrast to the widely accepted geochemical interpretation, we
propose a fibre growth model that places coral skeletons among the typical
''matrix mediated'' structures. The crystal-like fibres are built by
superimposition of few micron-thick growth layers. A biomineralization cycle
starts by the secretion of a mineralizing matrix and the final step is the
crystallization phase, during which mineral material grows onto the organic
framework. Thus, each growth layer is the actual Environment Recording Unit.
From a practical standpoint, these results may contribute to develop a new
high resolution approach of the environment recording by coral skeletons. |
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