The goals of this project are to determine 1) the collagen types synthesized and secreted by periodontal ligament (PDL) cells, 2) the quantitative and qualitative changes in collagen expression in PDL of moving teeth, 3) the mechanism of such changes, and 4) the cellular involvement in the altered collagen metabolism of moving teeth. In order to characterize the collagenous polypeptides synthesized by rat PDL cells, the cells will be isolated and cultured. RNA will be extracted and mRNA will be cell-free translated. The translation products will be analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Collagenous peptides will be identified by their sensitivity to degradation by bacterial collagenase. The polypeptides synthesized by PDL RNA will be compared to cell-free translation products of types I, II, V and IX collagens synthesized from the mRNA isolated from rat chondrosarcoma tissue. cDNAs encoding novel, short-chain PDL collagenous polypeptides will be synthesized with size-fractionated mRNA, inserted into vectors, amplified and isolated for use as probes on Northern and Southern blots and sequencing. In situ hybridizations, along with immunohistochemistry and radioimmunoassays will be used to localize and quantify the products of different collagen genes in the PDL. These studies are to be carried out in rats; however, the information that will be derived from them should be valuable in elucidating the mechanisms underlying the orthodontic movement of teeth in humans.