Tetrahymena thermophila strain B could regenerate approximately 10% of its somatic ciliary mass in concentrations of cycloheximide believed to block all cytoplasmic protein synthesis. A quantitative study of the relative numbers and lengths of cilia regenerated in the presence and absence of cycloheximide under a variety of conditions suggested that specific initiation and elongation protein factors are involved in the control of ciliary morphogenesis in Tetrahymena.The ciliated protozoan Tetrahymena can regenerate its cilia in both nutrient and non-nutrient medium. It has been shown in a number of laboratories that regeneration is completed within about a 2-h period after deciliation by the Rosenbaum and Carlson calcium shock procedure (1,5,8,10,13). It has also been shown by several laboratories that there is an induced synthesis of ciliary proteins associated with this regeneration (1, 5, 13; S. D. Guttman and M. A. Gorovsky, J. Cell Biol. 67:149a, 1975). From the beginning, however, label dilution studies have consistently indicated that only part of the protein actually incorporated into the regenerating cilia is the result of this induced synthesis (5, 7, 13; Guttman and Gorovsky, J. Cell Biol. 67:149a, 1975). This suggests that a significant proportion of the structural protein in regenerated cilia comes from preexisting cytoplasmic pools. It has also been found recently that tubulin induction occurs only after ciliary regeneration is well under way (1, 5), which leads to the same conclusion. The substantial use of stored proteins in ciliary regeneration by Tetrahymena suggests the operation of specific assembly control mechanisms which may be of general interest. into the postulated assembly control mechanisms. Our results suggest that specific initiation and elongation factors may be involved in the control of ciliary assembly in Tetrahymena. MATERIALS AND METHODST. thermophila strain B stock cultures were maintained axenically in a tryptone medium (3) and grown for experiments in an enriched proteose-peptone medium (PPYGFe) containing yeast extract, glucose, and iron-ethylenediaminetetraacetic acid (15). Flask cultures containing 150 ml of growth medium were grown to a density of 3 x 105 cells/ml at 22°C. The cells were then rinsed by gentle centrifugation three times and suspended in 150 ml of the Carlsberg Institute inorganic medium (CBI-IM) (6). All experiments were begun after maintenance of the cells in inorganic medium for 4 h.The cells were deciliated for regeneration experiments by the method of Rosenbaum and Carlson (10). In this method, the cells are concentrated in a small amount of a deciliation medium and briefly exposed to a high concentration of calcium. The cilia, weakened at the base by the calcium shock, are easily removed by drawing the cell suspension through a no. 16 needle fitted to a syringe. Immediately after the deciliation procedure, the cell suspension is diluted tenfold in inorganic medium, rinsed once, and resuspended in 150 ml of inorganic medium. The deciliated cells we...
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