Induction of steroid binding sites (receptors) and presence of steroid hormones in the unicellular Tetrahymena pyriformis.

The unicellular Tetrahymena does not normally possess a steroid hormone (dehydroepiandrosterone, DHEA) or a glucocorticoid (dexamethasone) receptor, but both kinds of receptor can be induced in it by pretreatment (imprinting) with the adequate hormone. The specific receptors which arise are demonstrable experimentally. Examination of Tetrahymena cells for endogenous steroids by the radioimmunoassay (RIA) technique detected an appreciable concentration of DHEA and DHEA sulphate, and lesser concentrations of testosterone and estradiol in this unicellular organism.