Chemical reception mechanisms at a low level of phylogeny. Influence of polypeptide hormones and non-hormone polypeptides on the growth of Tetrahymena.

The polypeptide hormones insulin, glucagon, thyrotropin (TSH), pregnant mare serum gonadotropin (PMSG) and adrenocorticotropin (ACTH) stimulated the growth of the Tetrahymena, and the non-hormone polypeptides (bovine serum albumin (BSA), protamine) had a similar effect. Re-exposure after 24 h accounted for a greater growth stimulation than pre-exposure alone in cultures treated with TSH and PMSG, and re-exposure after 7 days had such effect in all polypeptide-treated cultures. It follows that the non-hormone polypeptides had a similar imprinting potential to the polypeptide hormone. The non-hormone polypeptides were also able to cross-imprint for one another, i.e. pre-exposure to one enhanced the binding capacity of the cells for the other on re-exposure, and vice versa. A single treatment with a polypeptide hormone or a non-hormone polypeptide did in itself stimulate the growth of the Tetrahymena for as long as 1 week.