标题： $α$-卫星重复数组的起源来自线粒体分子化石——在核基因组中的顺序插入、扩展和进化 显示英文标题

标题： Origin of $α$-satellite repeat arrays from mitochondrial molecular fossils -- sequential insertion, expansion, and evolution in the nuclear genome

摘要： α卫星DNA是由150-400 bp单元组成的大型串联数组，其起源仍然是一个进化之谜。 在这项研究中，我们在宝石小蜂Nasonia vitripennis的核基因组中鉴定出1,545个α卫星类似（SatL）重复单元。 其中，39个SatL拷贝在线粒体中组织成两个回文数组，导致基因组大小增加了50%。 值得注意的是，对1,516个核SatL重复的基因组邻域分析显示，它们位于NuMT（核线粒体DNA）区域，并且SatL系统发育与线粒体基因和NuMT假基因完美匹配。 这些结果支持SatL数组起源于过去50万年内，从其姐妹物种N. giraulti分化后，十次独立的线粒体插入事件进入核基因组。 显著的重复GC百分比升高（从33.9%到50.4%）是由于线粒体中两个线粒体SatL数组的回文序列配对促进了GC偏向的基因转换，这是SatL序列快速进化的一个标志。 核SatL重复数组经历了大量的拷贝数扩展，从12-15个（SatL1）到超过400个拷贝（SatL4）。 最古老的SatL4B数组由四种来自祖先重复AT丰富区删除的重复单元组成，并通过复制进化出了复杂的高级结构。 我们还发现了类似重复插入到Muscidifurax的核基因组中，这表明这种机制可能在昆虫中很常见。 这是首次报告核卫星序列的线粒体起源，我们的发现为卫星DNA的起源和进化提供了新的见解。 显示英文摘要

摘要： Alpha satellite DNA is large tandem arrays of 150-400 bp units, and its origin remains an evolutionary mystery. In this research, we identified 1,545 alpha-satellite-like (SatL) repeat units in the nuclear genome of jewel wasp Nasonia vitripennis. Among them, thirty-nine copies of SatL were organized in two palindromic arrays in mitochondria, resulting in a 50% increase in the genome size. Strikingly, genomic neighborhood analyses of 1,516 nuclear SatL repeats revealed that they are located in NuMT (nuclear mitochondrial DNA) regions, and SatL phylogeny matched perfectly with mitochondrial genes and NuMT pseudogenes. These results support that SatL arrays originated from ten independent mitochondria insertion events into the nuclear genome within the last 500,000 years, after divergence from its sister species N. giraulti. Dramatic repeat GC-percent elevation (from 33.9% to 50.4%) is a hallmark of rapid SatL sequence evolution in mitochondria due to GC-biased gene conversion facilitated by the palindromic sequence pairing of the two mitochondrial SatL arrays. The nuclear SatL repeat arrays underwent substantial copy number expansion, from 12-15 (SatL1) to over 400 copies (SatL4). The oldest SatL4B array consists of four types of repeat units derived from deletions in the AT-rich region of ancestral repeats, and complex high-order structures have evolved through duplications. We also discovered similar repeat insertions into the nuclear genome of Muscidifurax, suggesting this mechanism can be common in insects. This is the first report of the mitochondrial origin of nuclear satellite sequences, and our findings shed new light on the origin and evolution of satellite DNA.