Yoshida Takanori, Furihata Hazuka Y, Kawabe Akira
Faculty of Life Sciences, Kyoto Sangyo University.
Genes Genet Syst. 2017 Sep 12;92(1):27-33. doi: 10.1266/ggs.16-00039. Epub 2017 Feb 22.
Sequences homologous to organellar DNA that have been integrated into nuclear genomes are referred to as nuclear mitochondrial DNAs (NUMTs) and nuclear plastid DNAs (NUPTs). NUMTs in nine plant species were analyzed to reveal the integration patterns and possible factors involved. The cumulative lengths of NUMTs in two-thirds of species analyzed were greater than those of NUPTs observed in a previous study. The age distribution of NUMTs was similar to that of NUPTs, suggesting similar mechanisms for integration and degradation of both NUPTs and NUMTs. Nuclear genome size and the cumulative length of NUMTs showed a significant positive correlation for older but not younger NUMTs. The same correlation was also found between nuclear genome size and older NUPTs in 17 species. These results suggested that genome size is a key factor to determine the cumulative length of relatively older NUPTs/NUMTs. Although the factor(s) determining the cumulative length of younger NUPTs/NUMTs is unclear, these sequences may be more deleterious, which could explain the different manner of determining the cumulative length of younger NUPTs/NUMTs in nuclear genomes. In addition, a relationship between the cumulative length of integrated NUMTs and complexity of mitochondrial genomes (i.e., the number of repeats) was found. The results indicate that the structural complexity of both NUMTs and their original mitochondrial sequences affects integration and degradation processes.
整合到核基因组中的与细胞器DNA同源的序列被称为核线粒体DNA（NUMTs）和核质体DNA（NUPTs）。对9种植物的NUMTs进行了分析，以揭示其整合模式及可能涉及的因素。在三分之二被分析的物种中，NUMTs的累积长度大于先前研究中观察到的NUPTs的累积长度。NUMTs的年龄分布与NUPTs相似，这表明NUPTs和NUMTs在整合和降解方面具有相似的机制。对于较古老而非较年轻的NUMTs，核基因组大小与NUMTs的累积长度呈现出显著的正相关。在17个物种中，核基因组大小与较古老的NUPTs之间也发现了同样的相关性。这些结果表明，基因组大小是决定相对古老的NUPTs/NUMTs累积长度的关键因素。虽然决定较年轻的NUPTs/NUMTs累积长度的因素尚不清楚，但这些序列可能更具危害性，这可以解释核基因组中决定较年轻的NUPTs/NUMTs累积长度的不同方式。此外，还发现了整合的NUMTs的累积长度与线粒体基因组复杂性（即重复序列的数量）之间的关系。结果表明，NUMTs及其原始线粒体序列的结构复杂性都会影响整合和降解过程。
