Radiation induced formation of giant cells in Saccharomyces uvarum. IV. Macromolecular synthesis and protein patterns.

X-irradiated (1.0 kGy) yeast cells (Saccharomyces uvarum, ATCC 9080), grown in liquid medium stop their mitotic activities and form giant cells by development of several buds which do not separate from mother cells. Depending on the time in culture, wet and dry weights per cell, protein-RNA- and DNA- contents per cell as well as incorporation rates of 14C-leucine per cell and per hour and patterns (isoelectric focussing) of water soluble proteins were studied. Weights per cell, RNA and protein contents per cell and 14C-leucine incorporation rates increase markedly in giant cells, whereas DNA content per cell is only duplicated. Protein patterns in isoelectric focusing show one interesting difference. In samples from giant cells one protein band (IP = 6.63) decreases after 8 h in culture and later on disappears completely. This finding is not due to primary damage in X-irradiated DNA but seems to be related to the control of cell cycle events.