Pheromone and insulin induced chemotaxis in Tetrahymena

Cytodex spheres impregnated with insulin had a repellent effect at the first encounter and an attractive effect at the second encounter with Tetrahymena pyriformis. Tricosene, one of the two pheromones investigated had a positive chemotactic effect at the first encounter with the cells and this effect was increased following pretreatment (imprinting) with tricosene. Bornyl acetate expressed a negative effect on first use and was neutral on imprinted cells. The experiments demonstrate that not only hormones but also pheromones can serve as signal molecules for Tetrahymena. Moreover, the development of imprinting was observed. The effects and the imprintability were not a general characteristic of the pheromones which originate from the individual characters of the molecules. The development of imprinting can alter the direction of the effect of stimulus mediated by receptors.