Mol Biol Evol. 2011 Jan;28(1):1-5. doi: 10.1093/molbev/msq217. Epub 2010 Aug 18.
The transposition of parts of the mitochondrial (mt) genetic material into the nuclear genome (NUMTs) occurs in a wide range of eukaryotes. Here, we show that NUMTs exist for nearly all regions of the mt genome in the demosponge Amphimedon queenslandica, a representative of the oldest phyletic lineage of animals. Because the sponge NUMTs are small and noncoding, and transposed via a DNA intermediate, as in eumetazoans, we infer that the transpositonal processes underlying NUMT formation in contemporary animals existed in their most recent common ancestor. In contrast to most bilaterians, Amphimedon NUMTs are inserted into regions of high gene density. Given the common features of metazoan NUMTs, the reduction in animal mt genome sizes relative to other eukaryotes may be the product of the mt DNA transposition mechanisms that evolved along the metazoan stem.
线粒体（mt）遗传物质的部分转移到核基因组（NUMTs）在广泛的真核生物中发生。在这里，我们表明，NUMTs 存在于有孔虫 Amphimedon queenslandica 的 mt 基因组的几乎所有区域，它是动物最古老的系统发育谱系的代表。由于海绵 NUMTs 很小且是非编码的，并且通过 DNA 中间体进行转座，就像在后生动物中一样，我们推断，后生动物 NUMT 形成的转座过程存在于它们最近的共同祖先中。与大多数两侧对称动物不同， Amphimedon 的 NUMTs 插入到高基因密度的区域。鉴于后生动物 NUMTs 的共同特征，与其他真核生物相比，动物 mt 基因组大小的减少可能是沿后生动物主干进化的 mtDNA 转座机制的产物。
