RNA interference plays a major role in biology of ciliates. Diverse small RNAs regulate many processes in vegetative cells of ciliates Tetrahymena and Paramecium. Different types of endogenous and exogenous nucleotide sequences
induce different RNAi pathways resulting in silencing of the homologous sequences in the macronuclear genome. Likely this way ciliates are able to quickly inactivate heterogeneous sequences and to adapt efficiently to the environmental
conditions and external stimuli.