Intra- and intercellular communication systems in ciliates

Intracellular signaling and cell-cell interactions are basic features of li ving organisms. Ciliated protozoa show complex mechanisms of intracellular signaling, as is demonstrated for the phagosomal pathway. Although unicellu lar, ciliates also communicate with other cells, for example, with invading or symbiotic micro-organisms, some of which are dwelling in the nuclei. In predator-prey interactions chemical signals (kairomones) released by certa in predators induce defensive morphological or behavioral changes in the pr ey ciliates. In intercellular communication sensu strictu ciliate cells com municate with each other, for example, in sexual propagation. A variety of sexual signals have been found to function in preconjugant interaction. Man y phenomena of cellular communication in ciliates appear to be similar to t hose found in multicellular organisms.