Der Glucosestoffwechsel dereprimierten pflanzlichen Speicherparenchyms nach Hemmung der Mitoseaktivitat durch Tris‐ (hydroxymethyl‐) aminomethane

Abstract

The transition from resting to mitotically active potato tissue (excised disks) is accompanied by and virtually dependent on transcription, translation and increased metabolic activity. Thus enhanced RNA‐ and protein‐syntheses are well known features of potato tuber slices, allowing the cells to raise the level of several metabolic pathways (i.e., starch breakdown, pentose phosphate shunt, glycolysis, respiration and others) and ultimately leading to mitotic activity. Mitosis can be totally, yet reversibly suppressed by incubation of the tissue fragments in Tris (hydroxymethyl)‐aminomethane buffer. Neither total respiration nor its sensitivity to several inhibitors is affected during blockage of mitosis. Fluctuations in the levels of glucose‐6‐phosphate, fructose‐6‐phosphatc, phospho‐enolpyruvate and pyruvate are exactly the same in Tris‐inhibited as in non‐inhibited cells. Thus the Tris ion is not modifying glucose catabolism. The same is true for the time‐course of activity of hexokinase, glucose‐6‐phosphate‐ and 6‐phosphogluconate dehydrogenase, glucosephosphate isomerase, triosephosphate isomerase, enolase, phosphoglyceromutase and “malic enzyme”. Although the rapid decrease in activity of phosphoglucomutase, aldolase, pyruvate kinase and glutamic‐pyruvic transaminase after slicing (characteristic for non‐inhibited cells) does not occur in Tris‐treated tissue, these small differences are not thought to be causative in inhibition of mitosis. The results indicate, that nucleic acid metabolism is more likely the target of the Tris‐ion.