Journal of Cell Science, Vol 5, 143-162, Copyright © 1969 by Company of Biologists

Revised on October 28, 1968

Synthesis of Cortical Proteins in Tetrahymena

¹ Department of Zoology, University of Iowa, Iowa City, Iowa, U.S.A.
² Biological Institute, Carlsberg Foundation, Copenhagen, Denmark

The synthesis of proteins of the oral apparatus in the ciliate Tetrahymena pyriformis has been studied in relation to the development of this organelle system within the cell. Oral proteins were labelled in both logarithmic phase and synchronized cells by growing the cells in the presence of tritiated amino acids. Estimates of the relative amounts of radioactive protein within the old and developing oral structures under various experimental conditions were made by radioautography of the structures after isolation from the cells. Evidence is presented that (i) mature oral structures undergo constant protein turnover; (ii) new oral organelle systems are constructed largely from proteins which are made prior to organelle differentiation and which are contained within a cytoplasmic pool and possibly also in pre-existing oral apparatuses; (iii) there are regular features in the label incorporation and conservation data which correlate well with morphological changes known to occur in the anterior (old) oral apparatus just prior to division; (iv) incorporation of labelled amino acids into the protein of oral structures does not occur during the synchronizing heat shocks; and (v) incorporation of label into the developing oral primordium does occur during primordium development, although it is not known whether these structural proteins are those demonstrated by other studies for which synthesis during development is an absolute requirement.