title: Purine metabolism in germinating wheat embryos.
abstract: 1. Both the acid-soluble fraction and the nucleic acid fraction of wheat embryos were extensively labelled after incubation for 6hr. in the presence of [8-(14)C]adenine. Subsequent incubation in the absence of labelled adenine resulted in no loss of radioactivity to the medium during a 48hr. period. Radioautography indicated that during this period there was a continuous increase in the radioactivity present in the acid-insoluble fractions of the root and leaf tissues relative to that present in the coleorhiza and coleoptile. 2. During incubation at 25 degrees there was a 26-fold increase in the activity of 3'-nucleotidase between 4hr. and 24hr.; the activities of enzymes hydrolysing AMP and IMP increased to a smaller extent. The activities of adenine phosphoribosyltransferase and hypoxanthine phosphoribosyltransferase increased three- to five-fold during incubation at 25 degrees for 24hr. 3. Adenosine kinase, inosine phosphorylase and 5-phosphoribosyl pyrophosphate synthetase activities were high in extracts from dry embryos and did not increase during 48hr. at 25 degrees . 4. The increase in 3'-nucleotidase activity was prevented by cycloheximide, cryptopleurine or incubation at 4 degrees , but not by actinomycin D; these treatments did not depress the activity of the other enzymes measured. 5. The results are discussed in relation to RNA translocation within the wheat embryo during germination.
mesh_terms: D000225:Adenine / Q000378:metabolism; D000227:Adenine Nucleotides / Q000378:metabolism; D001345:Autoradiography; D002247:Carbon Isotopes; D007042:Hypoxanthines / Q000378:metabolism; D009705:Nucleosides / Q000378:metabolism; D009708:Nucleotidases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010428:Pentosephosphates / Q000378:metabolism; D010756:Phosphoric Acids / Q000378:metabolism; D010770:Phosphotransferases / Q000378:metabolism; D010944:Plants / Q000201:enzymology / Q000378:metabolism*; D011687:Purines / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D012639:Seeds; D014166:Transferases / Q000378:metabolism; D014908:Triticum / Q000254:growth & development*
chemical_list: D000227:Adenine Nucleotides; D002247:Carbon Isotopes; D007042:Hypoxanthines; D009705:Nucleosides; D010428:Pentosephosphates; D010756:Phosphoric Acids; D011687:Purines; D012313:RNA; D014166:Transferases; D010770:Phosphotransferases; D009708:Nucleotidases; D000225:Adenine