The cilia of Tetrahymena pyriformis: Fractionation of isolated cilia

Abstract

Summary Improved methods of culture and isolation have resulted in the production of 200 mg amounts of segmented cilia from Tetrahymena pyriformis The cilia were inoculated subcutaneously into rabbits, and produced strain-specific immobilizing antisera. When these antisera were tested against extracts of cilia in gel diffusion plates, several precipitin lines were observed. Extraction of the cilia with 3.1 N acetic acid dissolved 80-90 per cent of the ciliary N, and most of the N was recovered as a gel on dialysis against water. These acid extracts gave three boundaries on ultracentrifugation, with sedimentation coefficients of c. 1.7 S, 4 S and 9 S. After precipitation of the extracts with trichloroacetic acid, a fraction was soluble in ethanol and gave a single precipitin line in the gel diffusion plates and a single boundary in the ultracentrifuge, which was identified with the 4-S peak. The ethanol-soluble fraction gave a positive biuret test, and after hydrolysis yielded amino acids, amounting to up to 80 per cent of the weight of the fraction. This amino acid composition was different from those of whole isolated cilia and the ethanol-insoluble fraction. Characteristic features included very small contents of proline and methionine, and large contents of aspartic acid, glutamic acid and alanine. These observations suggest that one of the main components of cilia is an ethanol-soluble protein with a distinctive acid composition.