In the phylogeny of signaling chemotactic responsiveness embodies one of the most ancient biological responses of single cells. Recent studies of the required signaling and effector mechanisms of chemotaxis demonstrate that there are significant differences in chemotaxis of prokaryotic and eukaryotic cells.

    On the basis of reference data in literature eukaryotic protozoa and especially Tetrahymena pyriformis serve a special role in the investigation of chemotactic signaling. Pionir works of research groups of Kidder, Schultz, Nozawa, Roth and Csaba demonstrated that Tetrahymena possess homologous signaling mechanisms (receptors, second messenger systems, metabolic and auto- or paracrine activity) to the higher ranked animals.

    On the other hand, chemotaxis is one of the most essential, cell-physiological response of these free-swimming unicellular organisms. Investigation of molecular approaches of this function potentially helps to understand “tactics” and “strategy” of this very ancient form of biological activity, while on the other hand it provides the possibility to describe basic, however well-conserved backgrounds of signaling, working in invertebrate and vertebrate levels of phylogeny.