The Regulation of Photosynthetic Activity in Chlamydomonas Reinhardi

摘要

The y-2 mutant strain of the unicellular green alga Chlamydomonas reinhardi can be caused to undergo bleaching and regreening under rigidly defined and controllable conditions. The development of several photosynthetic reactions during the regreening process were studied. The rates of several reactions remained constant during the first two to three hours of regreening and then increased rapidly. It is suggested that this rapid increase in photosynthetic activity is triggered by the development of a structurally active chloroplast or sub-unit of the chloroplast. This structural unit could provide for physical separation of products and even for their transport to regions of the cell suitable for their protection and metabolism. It is certain that the proteins, particularly the chloroplastic proteins, play a predominant role since the function of the chlorophylls not only depends on the activity of several enzymes, but also on photochemical reactions in which the properties of the pigment-protein complex are essential features. Several forms of this complex appear to exist and to be able to change into one another during development. The regreening cell is a dynamic system whose photosynthetic capabilities are bound to the chloroplast and vary with the environmental conditions. (Author)