In ciliates, with every sexual event the transcriptionally active genes of the sub-chromosomic somatic genome that resides in the cell macronucleus are lost. They are de novo assembled starting from ‘Macronuclear Destined Sequences’ that arise from the fragmentation of transcriptionally silent DNA sequences of the germline chromosomic genome enclosed in the cell micronucleus. The RNA-mediated epigenetic mechanism that drives the assembly of these sequences is subject to errors which result in the formation of chimeric genes. Studying a gene family that in Euplotes raikovi controls the synthesis of protein signal pheromones responsible for a self/not-self recognition mechanism, we identified the chimeric structure of an 851-bp macronuclear gene previously known to specify soluble and membrane-bound pheromone molecules through an intron-splicing mechanism. This chimeric gene, designated mac-er-1*, conserved the native pheromone-gene structure throughout its coding and 3′ regions. Instead, its 5′ region is completely unrelated to the pheromone gene structure at the level of a 360-bp sequence, which derives from the assembly with a MDS destined to compound a 2417-bp gene encoding a 696-amino acid protein with unknown function. This mac-er-1* gene characterization provides further evidence that ciliates rely on functional chimeric genes that originate in non-programmed phenomena of somatic MDS recombination to increase the species genetic variability independently of gene reshuffling phenomena of the germline genome.

在纤毛虫中，每次性行为都会丢失位于细胞大核中的亚染色体体细胞基因组的转录活性基因。它们被从头组装从“开始中号acronuclear d estined小号equences”从封闭在微核细胞的种系基因组chromosomic的转录沉默的DNA序列的片段化出现。驱动这些序列装配的RNA介导的表观遗传机制容易出错，导致嵌合基因的形成。研究Euplotes raikovi中的一个基因家族通过控制负责自我/非自我识别机制的蛋白质信号信息素的合成，我们确定了一个851-bp的大核基因的嵌合结构，该基因以前已知是通过内含子剪接机制指定可溶和膜结合的信息素分子的。该嵌合基因称为mac-er-1 *，在其整个编码区和3'区均保留了天然信息素基因的结构。取而代之的是，其5'区域在360 bp序列的水平上与信息素基因结构完全无关，该信息源来自带有MDS的装配，该MDS旨在复合2417 bp基因编码功能未知的696个氨基酸的蛋白质。这个macer-1 * 基因表征提供了进一步的证据，纤毛虫依赖于起源于体细胞MDS重组的非程序化现象的功能性嵌合基因来增加物种遗传变异性，而与种系基因组的基因改组现象无关。