Abstract
Chitons are marine molluscs that feed by rasping food from the rocks on which they live. They achieve this with the aid of teeth that are hardened through the incorporation of iron and calcium biominerals. The chiton radula is comprised of teeth at various stages of maturation, and the different minerals are incorporated into specific teeth at very precise stages of radula development. While much is known about the minerals that are deposited and the process of radula mineralisation, to date there have been no studies undertaken to identify the genes that control the mineralisation process. A molecular approach has been employed to further our understanding of radula biomineralisation in the chiton Acanthopleura hirtosa. The radula sac was collected from 20 chitons and RNA extracted and used as a template for cDNA synthesis followed by PCR amplification and cloning, thus generating a suite of expressed sequence tags (ESTs). 1152+T58 of the ESTs have been sequenced, and 500 unique sequences further selected for inclusion in a 'Combimatrix' oligo microarray. This array will be hybridized with probes from discrete tissue sections of the radula sac, corresponding to specific mineralisation stages. A high level of sequence divergence has been identified between most of the ESTs and sequences available from other organisms. It is anticipated that this study will identify genes associated with specific radula biomineralisation events, and thus shed light on the molecular aspects of this process. In addition, the sequencing of over 1000 ESTs from chiton provides valuable genomic information that could be useful for the study of the biology of this species.