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Article

Growth of protein-doped rhombohedra in the calcitic shell of craniid brachiopods

Citation
Williams A, Cusack M & Brown KL (1999) Growth of protein-doped rhombohedra in the calcitic shell of craniid brachiopods. Proceedings of the Royal Society B: Biological Sciences, 266 (1428), pp. 1601-1607. https://doi.org/10.1098/rspb.1999.0821

Abstract
The secondary shell of the living inarticulated brachiopod Neocrania consists of calcitic laminae interleaved with organic sheets, predominantly a 444 kDa protein with high levels of aspartic acid-asparagine and glutamic acid-glutamine. Laminae consist of tabular (01.4) rhombohedra that are composed of spherular or rhombohedral granules, ca. 30 nm in size. Rhombohedra increase by planar or spiral growth as granular, monolayered plates that commonly act as foundations for multilayered tablets up to 300 nm or so high. Rough (Ok.1) faces, kinked by cleavage, usually develop at either end of the long diagonals of rhombohedra, the edges of which may support ramparts that can accrete centripetally to enclose any organic material situated at tablet centres. Induced degradation by proteinase K shows that sectors subtended by (Ok.1) steps are doped by a fibrous polymer, identified as an exclusively intralaminar glycosylated 60 kDa protein. A 44 kDa protein has also been extracted from laminae and is presumably incorporated into tablets by centripetally growing ramparts.

Keywords
Protein-doped calcite; spirally growing rhombohedra; organocalcitic brachiopod shells;

Journal
Proceedings of the Royal Society B: Biological Sciences: Volume 266, Issue 1428

StatusPublished
Author(s)Williams, Alwyn; Cusack, Maggie; Brown, Karen L
Publication date31/08/1999
Publication date online07/08/1999
URLhttp://hdl.handle.net/1893/25006
PublisherThe Royal Society
ISSN0962-8452
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