Amines in Algae. 8. Effects of a Modified Light Regime and of Inhibitors of DNA Synthesis on Polyamine Levels in...

Chlorella emersonii (strain 211-8b) was grown synchronously in a 16 : 8 h light-dark cycle. The normal kinetic coincidence between the concentration changes per initial cell of DNA, putrescine, and spermidine disappeared to a greater or lesser degree upon shifting the light-dark cycle from 16 :8 h to 10 : 14 h as well as in the presence of inhibitors of DNA synthesis. For example, timing, and initial rates of synthesis of putrescine and spermidine remained normal, when DNA synthesis was blocked by 5-fluoro deoxy uridine. Also during recovery from the unspecific inhibition by hydroxy urea the DNA/putrescine/spermidine coincidences disappeared. Hence, these coincidences which are observed under standard conditions, may be essentially incidental. By contrast, the RNA/norspermidine coincidence was maintained to a greater or lesser extent under all conditions tested. The concentration of norspermidine was found to be 25 ± 5 mg per gram of RNA.