Mineral phase in linguloid brachiopod shell: Lingula adamsi




Ramin Rohanizadeh [raminr@pharm.usyd.edu.au], Faculty of Pharmacy, Department of Pharmaceutics, University of Sydney, Sydney, NSW 2006, Australia; and Racquel Z. LeGeros [rzl1@nyu.edu], Calcium Phosphate Research Laboratory, College of Dentistry, Department of Biomaterials and Biomimetics, New York University, 345 East 24th Street, New York, NY 10010, USA.


The linguloid brachiopod shell family has been the focus of several studies because of the similarity in the composition of the mineral phase of these shells to that of human bone. However, ultrastructural features of Lingula shells have not yet been fully demonstrated at high magnification using Transmission Electron Microscopy (TEM) and Electron Diffraction. Ultrastructural characterization of the mineral phase in Lingula shells will improve our understanding of the biomineralization processes and mineral/organic interaction in more complex systems such as in bone or in other human mineralized tissues. In this study, the mineral phase of Lingula adamsi was characterized using a combination of ultrastructural and crystallographic techniques. The results showed that L. adamsi shells consist of apatite crystals of varying size, shape, and orientation in different areas of the shell. The c-axis of apatite was parallel to the shell surface and crystals were organized in different laminae. Compared to trabecular bovine bone, L. adamsi shells demonstrated a higher crystallinity and a lower amount of carbonate and organic compounds. This study therefore demonstrated how dissimilar organic matrix between L. adamsi shell and trabecular bone can modify the ultrastructural characteristics of apatite crystals in these two biomineralized tissues.