Siliceous tablets in the larval shells of apatitic discinid brachiopods

Science

Volumn 279, Issue 5359, 1998, Pages 2094-2096

  Williams, Alwyn ^a   Cusack, Maggie ^a   Buckman, James O ^a   Stachel, Thomas ^b  

^a UNIVERSITY OF GLASGOW   (United Kingdom)

^b GOETHE UNIVERSITY   (Germany)

Author keywords

[No Author keywords available]

Indexed keywords

APATITE; CALCIUM CARBONATE; GLYCOSAMINOGLYCAN; SILICON DIOXIDE;

BIOMINERALIZATION; BRACHIOPOD; SHELL; SILICA;

ARTICLE; FOSSIL; METAZOON; MINERALIZATION; NONHUMAN; PRIORITY JOURNAL;

EID: 0032571414     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.279.5359.2094     Document Type: Article

References (21)

1. A. Williams et al., in Introduction, vol. 1 of Treatise on Invertebrate Paleontology: Part H, Brachiopoda, R. Kaesler, Ed. (Geological Society of America and Univ. of Kansas Press, New York, and Lawrence, KS, 1997).
2. A. Williams, M. Cusack, J. O. Buckman, Philos. Trans. R. Soc. London Ser. B., in press.
3. Glycosaminoglycans (GAGs), formerly known as mucopolysaccharides, are the principal component of the outer primary layer of the post-larval organophosphatic brachiopod shell.
4. L. E. Holmer, Fossils Strata 26, 1 (1989).
5. The larval surfaces of atmospherically dried immature dorsal valves of D. tenuis were irrigated with acetone. Strips of cellulose acetate film (10 μm thick) were placed on top and then peeled off, removing some biomineralized tablets.
6. The strips were carbon-coated and examined in a Cambridge 360 SEM (operating voltage = 20 kV, probe current = 132 pA).
7. Wavelength-dispersive maps for silicon and calcium were obtained by a JEOL superprobe (JXA 8900RL) on a gold-coated surface of the larval shell of D. tenuis (accelerating voltage = 8 kV, beam current = 6 nA, dwell time per pixel = 30 ms).
8. Dorsal valves of D. tenuis were incubated with the serine proteinase, subtilisin (E.C. 3.4.21.4) (2 μM) in sodium phosphate buffer (50 mM, pH 7.2), chitinase (E.C. 3.2.1.14) (1 μM) in sodium phosphate buffer (50 mM, pH 7.2), or an aqueous solution of sodium hypochlorite (bleach) (0.2% v/v) for 24 hours at 22°C. Solutions were removed and the specimens dried in a laminar-flow cabinet before gold coating for SEM study.
9. S. Mann and C. C. Perry, in Silicon Biochemistry, D. Evered and M. O'Connor, Eds. (Wiley, Chichester UK, 1986), pp. 40-58.
10. W. J. Landis, D. D. Lee, J. T. Brenna, S. Chandra, G. H. Morrison, Calcif. Tissue Int. 38, 52 (1986).
11. P. Li, C. Ohtsuki, T. Kokubo, K. Nakanishi, N. Soga, J. Am. Ceram. Soc. 75, 2094 (1992).
12. K. Ohiura et al., J. Biomed. Mater. Res. 25, 357 (1991).
13. G. Biernat and A. Williams, Palaeontology 13, 98 (1970).
14. A. Williams and L. E. Holmer, ibid. 35, 657 (1992).
15. L. Popov, J. Nõlvak, L. E. Holmer, ibid. 37, 627 (1994).
16. L. E. Holmer, L. E. Popov, R. Wrona, Palaeontol. Pol. 55, 37 (1996).
17. A. Williams and S. MacKay, Proc. R. Soc. London Ser. B 202, 191 (1978).
18. R. Ludvigsen, Neues Jahrb. Geol. Palaeontol. Monh. 3, 133 (1974).
19. A. Williams and G. B. Curry, in Brachiopods Through Time, D. I. MacKinnon, D. E. Lee, J. D. Campbell, Eds. (Balkema, Rotterdam, 1991), pp. 133-140.
20. H. A. Lowenstam and S. Weiner, On Biomineralization (Oxford Univ. Press, New York, 1989), p. 324.
21. Financial support from The Royal Society of London and the Natural Environment Research Council is greatly appreciated.