In the mitochondrial genomes of the filamentous Ascomycota, aside from the usual ‘core’ set of genes, one can encounter genes encoding for ribosomal protein S3 (rps3), N-acetyltransferase, and in a few instances aminotransferases. Based on a survey using sequence data from various databases, it was observed that these genes can be located within introns or exist as freestanding genes in intergenic regions. Furthermore, they can also be absent from fungal mitochondrial genomes. The rps3 gene is highly conserved among fungal mitochondrial genomes although examples were noted where the mtDNA version of this gene has been translocated into the nuclear genome. The N-acetyltransferase gene was less frequently encountered and may be a more recent import from the nuclear genome. Both genes serve as examples of genetic elements that appear to be capable of ‘cycling’ or mobilizing between introns and intergenic regions and possible between the nuclear and mitochondrial genomes. This ‘cycling’ mechanism is currently not understood but may involve recombination events and/or movement via RNA intermediates.

在丝状子囊线虫的线粒体基因组中，除了通常的“核心”基因集外，还可以遇到编码核糖体蛋白S3（rps3），N-乙酰基转移酶和少数情况下为氨基转移酶的基因。基于使用来自各种数据库的序列数据进行的调查，观察到这些基因可以位于内含子中，也可以作为独立基因存在于基因间区域中。此外，真菌线粒体基因组中也可能缺少它们。该RPS3该基因在线粒体真菌基因组中是高度保守的，尽管有一些例子表明该基因的mtDNA版本已转移到核基因组中。N-乙酰基转移酶基因较少见，可能是最近从核基因组导入的。这两个基因都作为遗传元件的例子，似乎能够在内含子和基因间区域之间以及在核和线粒体基因组之间“循环”或动员。目前尚不了解这种“循环”机制，但可能涉及重组事件和/或通过RNA中间体的运动。