Abstract
The chiton radula represents an excellent example of matrix-mediated biomineralization, with the incorporation of both iron and calcium minerals onto the organic matrix of the major lateral tooth cusps. In addition, it is an ideal tissue for the study of biomineralisation in situ since the different minerals are deposited at precise stages of radula development. These biominerals are thought to be delivered to the teeth by the overlying superior epithelial tissue, which surrounds the cusps during all stages of development. However, the mechanisms involved in transporting the mineralizing ions to the tooth cusps are poorly understood and as such, a fundamental step in the initial phase of biomineralization remains a mystery. The very presence of these minerals in chiton teeth places a physical limitation on the use of conventional preparation techniques, which has hampered detailed studies of the epithelialcells in the past. We have recently developed a method of limiting iron availability and suspending iron mineralization, thus facilitating the examination of epithelial cells via a range of techniques including light microscopy, transmission and scanning electron microscopy, X-ray microanalysis (EDS) and in situ Raman spectroscopy. An ability to now obtain structural and chemical information from radula teeth of chitons at advanced stages of maturation, will improve our understanding of the role played by the organic matrix and the superior epithelium in mineral formation and growth. Preliminary data on differences between control and iron-limited animals will be discussed, along with the implications of this study to the general field of biomineralization.