Role of Light in 5-Aminolevulinic Acid Formation in Wild Strain and Mutant C-2A' Cells of Scenedesmus obliquus

In dark-grown wild strain cells of Scenedesmus obliquus, 5-aminolevulinicacid (ALA) formation was induced by irradiation with a weakblue light, as in its mutant C-2A' cells. The induction wasinhibited by distamycin A, 6-methylpurine, cycloheximide andchloramphenicol. After the light induction, the ALA formationcould proceed in the dark as well as in the light, in such heterotrophicallygrown wild type cells, but not in the greening mutant C-2A'cells. In the latter, ALA formation was dependent on red light,as well as on blue light, in the presence of CMU. The amountsof protochlorophyll in the mutant cells increased upon cessationof illumination and decreased with subsequent irradiation withblue and red light. The possible role of protochlorophyll asa photoreceptor in regulation of ALA formation in the mutantcells is discussed. ¹Present address: Laboratory of Chemistry, Faculty of Medicine,Teikyo University, Otuka, Hachioji, Tokyo 192-03, Japan. (Received January 17, 1981; Accepted April 30, 1981)