ИСТИНА

Cellular behavior in Chlamydomonas reinhardrii is regulated by both photic and chemical stimuli. Tryptone inhibits the photoreceptor current in gametes of this microorganism and acts as a strong chemoattractant. The time course, concentration dependence and induction during gametogenesis of the tryptone-induced inhibition of the phOioreceptor current correlate with those of the gamete accumulation in front of a capillary. On the contrary, in pregametes and vegetative cells tryptone causes a weak stimulation of the photoreceptor current in the absence of any behavioral responses. The following conclusions can be drawn from these findings: 1) the tryptone-induced inhibition of the photoreceptor current in C. reinhardtii results from activation of a gamete-specific chemosensory system; 2) the photo- and chemosignaling pathways in this microbe are linked as early as is generation of the photoreceptor current. As the first step toward idemification of the active component of tryptone, we studied the influence of 18 common amino ac ids on the photoreceptor current. The results obtained show that chemoeffector properties of tryptone are likely associated with certain peptides rather than with any individual amino acid.