Comparative role of polyamines division and plastid differentiation of Euglena gracilis

• Published in: Biochimica et biophysica acta Vol. 675; no. 2; pp. 178 - 187
• Main Authors: Schuber, Francis, Aleksijevic, Alexandre, Blée, Elizabeth
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 03.07.1981
• Subjects: Carboxy-Lyases - antagonists & inhibitors; Cell Differentiation - drug effects; Cell division; Cell Division - drug effects; Differentiation; Euglena gracilis; Euglena gracilis - growth & development; Ornithine - analogs & derivatives; Ornithine - pharmacology; Ornithine decarboxylase; Ornithine Decarboxylase Inhibitors; Photic Stimulation; Polyamine; Polyamines - biosynthesis; Temperature; Cell division; Polyamine; Ornithine decarboxylase; Differentiation; Euglena gracilis
• ISSN: 0304-4165; 0006-3002; 1872-8006; 1878-2434
• DOI: 10.1016/0304-4165(81)90224-5

Regulation of polyamine biosynthesis during growth and differentation of Euglena gracilis was investigated. Increased activity of l-ornithine decarboxylase (EC 4.1.1.17), the enzyme which catalyzes the initial step in polyamine synthesis in Euglena, and accumulation of polyamines were observed prior to DNA replication in synchronous cultures of heterotropically or photoautotrophically grown cells. In photoatotrophic cells three maxima of polyamine synthesis were observed during the light period of the cell cycle. The transition from quiescence of active growth was accompanied in heterotrophic Euglena by a very large stimulation of ornithine decaboxylase activity and polyamine synthesis; the decrease in growth potential of these cells was correlated with a decrease in polyamine levels. In contrast, differentiation of Euglena, i.e., a shift from heterotrophic to photoautotrophic mode of living in the absence of division, led only to a minor stimulation of polyamine biosynthesis. α-Methylornithine, an inhibitor of ornithine decarboxylase, blocked the growth of heterotrophic Euglena, and depletion of intracellular polyamines decreased the differentiation rate. Both events could be reversed only by addition of putrescine to the growth medium. This study suggests that Euglena requires a minimal intracellular level of polyamines to grow and differentiate under optimal conditions. This requirement seems to be more stringent for cell division.