Induction of melatonin synthesis in Tetrahymena pyriformis by hormonal imprinting--a unicellular "factory" of the indoleamine.

Melatonin is present in Tetrahymena and its synthesis can be enhanced by pretreatment (imprinting) with melatonin. Two days after imprinting melatonin level is elevated in the cells and more elevated in the supematant. Such a minute quantity, as 10(-12) M melatonin for 1 hour is able to provoke imprinting, however the effect is more expressed using 10(-6) M. Maintenance in light conditions further elevated the amount of melatonin in the cells and supematant alike, related to the melatonin content of cells kept in darkness. The experiments call attention to the light-sensitivity of imprinting-provoked melatonin production in Tetrahymena and to the possibility of using this property for important physiological functions in higher grades of phylogeny.

Melatonin in the unicellular Tetrahymena pyriformis: effects of different lighting conditions.

Melatonin content in the cellular fraction and medium of Tetrahymena pyriformis GL cultures was measured at different time points of light and dark exposures. Tetrahymena produced, stored and secreted immunoreactive melatonin, which in displacement and HPLC studies, behaved like synthetic melatonin. There was not a continuous secretion of melatonin produced by the cells. In contrast to this, storage of melatonin was observed, which was more expressed in dark conditions. Prolonged light exposure suppressed melatonin production and secretion alike, however it did not block it completely.