Studies on the growth in culture of plant cells. XIX Changes in the levels of free and membrane-bound polysomes during the growth of Acer pseudoplatanus cells in batch suspension culture

Techniques have been established which give reproducible yields of total and of free and bound polysomes from cultured sycamore cells harvested at intervals throughout the cycle of growth followed in batch culture. High levels of polysomes build up in the cells during lag phase and lersist into early exponential growth.Later in the growth cycle, although theribosomalmaterial er unit volume of culture continues to rise, the content per cell of ribosomes and polysomes progressively declines until the cells enter the stationary phase. There is also a characteristic pattern of change in the relative proportions of free and bound polysomes throughout the growth cycle of the cultures. Both fractions contain different but significant levels of ribosomal subunits and monomers. The RNAs released from the free polysomes had a greater amount of poly(A) sequences than that from the bound polysomes. These fbdings are discussed in relation to the changing metabolic activities of the cells which occur during their progress through batch culture.