Ciliates are an interesting model system for investigating diverse functions of noncoding RNAs, especially in genome defence pathways. During sexual development, the ciliate somatic genome undergoes massive rearrangement and reduction through removal of transposable elements and other repetitive DNA. This is guided by a multitude of noncoding RNAs of different sizes and functions, the extent of which is only recently becoming clear. The genome rearrangement pathways evolved as a defence against parasitic DNA, but interestingly also use the transposable elements and transposases to execute their own removal. Thus, ciliates are also a good model for the coevolution of host and transposable element, and the mutual dependence between the two. In this review, we summarise the genome rearrangement pathways in three diverse species of ciliate, with focus on recent discoveries and the roles of noncoding RNAs.

纤毛虫是一个有趣的模型系统，用于研究非编码RNA的各种功能，尤其是在基因组防御途径中。在有性发育过程中，纤毛体细胞基因组通过去除转座因子和其他重复性DNA进行了大规模的重排和还原。这由许多大小和功能不同的非编码RNA指导，其程度只是最近才变得清楚。基因组重排途径进化为对寄生DNA的防御，但有趣的是，也使用转座因子和转座酶来执行其自身的去除。因此，纤毛虫也是宿主和转座因子共同进化以及两者之间相互依赖的良好模型。在这篇综述中，我们总结了三种纤毛虫的基因组重排途径，