title: Induction of ornithine decarboxylase in Leptomonas seymouri.
abstract: Ornithine decarboxylase, the initial enzyme of polyamine biosynthesis, was induced in vitro in Leptomonas seymouri, a parasite of Diptera, by resuspending stationary phase cells with fresh medium. Induction was biphasic with peaks at 2 and 8 h. Activity increased about 20-fold over 22 h under control conditions. Induction was completely blocked by cycloheximide and was suppressed by actinomycin D, alpha-amanitin, putrescine, spermidine and spermine. The enzyme half-life was 45 min in cells treated with cycloheximide 24 h post induction. These observations suggest the presence of a highly sensitive mechanism for regulation of ornithine decarboxylase as found in mammalian and other eukaryotic cells.
mesh_terms: D000546:Amanitins / Q000494:pharmacology; D000818:Animals; D003470:Culture Media; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D056890:Eukaryota / Q000187:drug effects / Q000201:enzymology*; D009955:Ornithine Decarboxylase / Q000096:biosynthesis*; D011073:Polyamines / Q000494:pharmacology; D011700:Putrescine / Q000494:pharmacology
chemical_list: D000546:Amanitins; D003470:Culture Media; D011073:Polyamines; D003609:Dactinomycin; D003513:Cycloheximide; D009955:Ornithine Decarboxylase; D011700:Putrescine