Protein biosynthesis during spiny dogfish (Squalus acanthias) enameloid formation

Little is known about protein biosynthesis during enameloid formation. The purpose of this study was to characterize protein biosynthesis during selachian amelogenesis. Experiments were conducted on intact shark tooth organs, surgically removed from the spiny dogfish, Squalus acanthias. These organs were cultured in medium labelled with [35S]-methionine during time periods ranging from 1 to 6 h in pulse/chase experiments. The proteins were extracted at the conclusion of the experiments for analysis by gel electrophoresis and fluorography. In addition, tooth organs were fixed and examined by light microscopic autoradiography. Through this outlined experimental strategy, protein biosynthesis during amelogenesis was examined. The findings suggest the ameloblasts, at early bell stage of tooth development, are biosynthetically more active than the incipient odontoblasts; and they are secreting two polypeptides, 55 and 43 kd, into the developing tooth extracellular matrix.