OCCURRENCE OF RIBOSOME-CONTAINING STRUCTURES IN PHORMIDIUM-LAMINOSUM PHOTOSYNTHETIC MEMBRANES

Cell membranes of the cyanobacterium Phormidium laminosum were separat ed into two fractions by centrifugation in a stepwise sucrose gradient . One fraction contained mature thylakoid membranes and the other one contained membranes morphologically similar to primary membranes of pe a etiochloroplasts. The latter ones represented an electron-transparen t base with numerous electron-dense inclusions. The predominant type o f the inclusions was rod-like structures containing presumably ribosom es.