title: Thymidine catabolism and the reutilization of its degradative products in Tetrahymena pyriformis. Metabolism of [2,6-14C2]thymidine and [2-14C]methylmalonic acid.
abstract: The operation of reductive pyrimidine catabolic and reutilization pathway in Tetrahymena pyriformis was investigated. Consistent with the proposed catabolic interconversions, radioactivity from [2,6-14C2]thymidine was recovered in respired CO2 30 min after its addition to the culture, whereas, consistent with the proposed anabolic interconversions, over 50% of the incorporated label was recovered in cellular macromolecules other than DNA 12 h after its addition. The chromatographic recovery of 14C radioactivity in monosaccharides from [2,6-14C2]thymidine as well as from [2-14C]methylmalonic acid, a key reutilization intermediate in this proposed pathway, further substantiated the operation of the required anabolic interconversions in this organism.
mesh_terms: D000818:Animals; D002241:Carbohydrates / Q000096:biosynthesis; D002250:Carbon Radioisotopes; D004247:DNA / Q000096:biosynthesis; D007700:Kinetics; D008055:Lipids / Q000096:biosynthesis; D008314:Malonates / Q000378:metabolism*; D008764:Methylmalonic Acid / Q000378:metabolism*; D014176:Protein Biosynthesis; D012313:RNA / Q000096:biosynthesis; D011865:Radioisotope Dilution Technique; D013769:Tetrahymena pyriformis / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism*
chemical_list: D002241:Carbohydrates; D002250:Carbon Radioisotopes; D008055:Lipids; D008314:Malonates; D012313:RNA; D008764:Methylmalonic Acid; D004247:DNA; D013936:Thymidine