Abstract
The candidate proteins that are involved in biomineralization in the radula of two limpet species C. toreuma and P. striata were studied during different developmental stages by proteome analysis and de novo protein synthesis. Protein patterns revealed by S35-l ling on SDS-PAGE gel differed at different developmental stages in both species, indicating the radulae undergo through some changes and a part of these changes may be related to the biomineralization process. Proteins were also found to be synthesized de novo and transported to the extracellular compartment. Among 1000 and 300 spots resolved in the two-dimensional gels in C. toreuma and P. striata respectively, comparison of different developmental stages of radulae revealed that 19 and 17 protein spots showed differential occurrence at different developmental stages of radulae formation. We found that for example in C. toreuma, a series of spots (spot No.19, 20, 21, 22, 23, 24, 25) and spot 53 appeared only around the radular sac and during stage I. The intensity of spot 155 greatly increased at stage I. Spot 79 presented high intensity 35S-l l at stage III. In P. striata, the autoradiography of two protein spots 40 and 41 were found in radular sac. Spot 262 appeared at stage II through early stage III. Spot 53 presented with high intensity 35S-l l at stage III. The preceding proteins might play a major role in the mineralization of the radulae. The broad spectrum of protein variability in expression observed during developmental stages of radulae might justify some speculation upon further biological implications of the biomineralization process.