Changes in the Fluorescence Emission Spectrum of Chlorella emersonii Induced by Cold Treatment; a Possible Regulative Feature of Energy Uptake

Fluorescence Emission Spectrum, Chlorella, Energy Uptake Algae, when slowly cooled down to around -5 °C, undergo a change in the fluorescence emissi­ on spectrum subsequently taken at liqu. nitrogen temperature. This change resembles the mag­ nesium effect described by Murata [BBA 189,171 — 181, (1969)] for isolated chloroplasts. Evidence is shown, that both effects are indeed analogous. Cooling the organisms seems to in­ crease the permeability of the thylakoids for cations and, thus, a depletion with concomitant changes in membrane structure. The system serves as a model for the probable in vivo control of pigment interaction through alteration of membrane properties.