The role of photosynthesis and respiration in the light-induced recovery of "giant" cells of the Emerson strain of Chlorella

The light-induced recovery of cell division and chloroplastdevelopment in "giant", "bleached" cells of the Emerson strainof Chlorella is unaffected by treatments (atrazine. CMU, incubationin a CO₂-free atmosphere) which interfere with photosynthesis.Anaerobic conditions or the presence of respiratory inhibitors(DNP, KCN, NaN₃) markedly suppress recovery. Recovery is accompaniedby a mobilization of the reserve starch which follows a linearcourse over the first 9 hr. Chloramphenicol (50 µg/ml),which inhibits chlorophyll synthesis and the development ofa photosynthetic capacity, is without effect on the early rateof starch mobilization. Evidence is presented that the contributionof photosynthesis towards recovery is only significant whenthe reserve starch has been depleted. Recovery does not requirecontinuous light; the critical light-stimulated processes apparentlytaking place during the first 9 hr. The possible nature of thelight stimulation of recovery is discussed. (Received June 18, 1973; )