Williams, A., Luter, C. and Cusack, M. (2001) The nature of siliceous mosaics forming the first shell of the brachiopod Discinisca. Journal of Structural Biology, 134(1), pp. 25-34. (doi: 10.1006/jsbi.2001.4366) (PMID:11469874)
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Abstract
The juvenile shell of the brachiopod Discinisca consists of a mosaic of micrometer-sized siliceous tablets embedded in a chitinous substrate. The first-formed tablets are secreted on glycocalyx by a newly differentiated collective of outer epithelial cells. They are mainly rhombic but may also be ellipsoidal, discoidal, or deformed and sporadically overlap one another. On the surrounding juvenile shell, secreted by an incipient outer mantle lobe, the tablets are nearly all perfect rhombic plates in rhombic arrays. Their constant size, arrangement, and centripetal crystallization suggest intracellular assembly. The tablets, which are normally bilamellar, consist of discrete aggregates of crystalline spherules of silica in rhombic arrays within an organic matrix of fibrous protein and, presumably, a soluble polysaccharide(s). Mosaic secretion ceases at about the time when juveniles settle on the sea bed, which more or less coincides with the secretion of a ring of lamellae around the mosaic, induced by rapid advances and retractions of the outer mantle lobe prior to deposition of the organophosphatic mature shell. Energy dispersion X-ray analyses of pelagic and newly settled juveniles show that phosphatic secretion, even in the site of the first-formed outer epithelial collective, does not begin until all siliceous secretion has ceased.
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Cusack, Professor Maggie |
| Authors: | Williams, A., Luter, C., and Cusack, M. |
| College/School: | College of Science and Engineering > School of Geographical and Earth Sciences |
| Journal Name: | Journal of Structural Biology |
| Publisher: | Elsevier |
| ISSN: | 1047-8477 |
| ISSN (Online): | 1095-8657 |
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