We analyzed the kinetoplast (mitochondrial genome) of Trypanosoma vivax strains from America and Africa to determine their precise architecture and to understand their adaptive response to mechanical transmission. The use of long-read based assemblies that retain individuality of tandem repeats, without erasing inter-copy variability, allowed us to investigate the evolutionary dynamics of repetitive kinetoplast-DNA. This analysis revealed that repeat elements located in edges of repeat clusters are less active in terms of renewal, whereas internal copies appear to undergo a permanent process of birth-and-death.

Comparing different American strains with the African Y486 strain, we found that in the former, protein coding genes from the maxicircle contain several function disrupting mutations that with very few exceptions are present in one or the other American strain but not in both, suggesting the absence of common ancestry for most of the genomic changes that led to their loss of oxidative phosphorylation capacity. Analysis of another component of kinetoplast, the minicircles, revealed great loss of diversity, and loss of their encoded guideRNAs. Both groups of American strains retain minimal sets required to edit the still functional A6-APTase and RPS12 genes. The extensive maxi- and minicircle divergence suggests a history of multiple introduction events in America of strains that probably started to degrade their kinetoplast in Africa. The notion that kinetoplast degradation began after incursion in America would imply a pace of accumulation of genetic changes considerably faster than other trypanosomatids.

我们分析了来自美洲和非洲的间日锥虫菌株的动质体（线粒体基因组），以确定它们的精确结构并了解它们对机械传递的适应性反应。使用基于长读长的组件保留串联重复的个体性，而不消除拷贝间的变异性，使我们能够研究重复运动体 DNA 的进化动力学。该分析表明，位于重复簇边缘的重复元素在更新方面不太活跃，而内部副本似乎经历了一个永久的生死过程。

将不同的美国菌株与非洲 Y486 菌株进行比较，我们发现在前者中，来自大环的蛋白质编码基因包含几个功能破坏突变，除了极少数例外存在于一种或另一种美国菌株中，但不存在于两者中，这表明不存在大多数基因组变化的共同祖先导致它们失去氧化磷酸化能力。对动质体的另一个组成部分小环的分析揭示了多样性的巨大损失，以及它们编码的引导RNA的损失。两组美国菌株都保留了编辑仍有功能的 A6-APTase 和 RPS12 基因所需的最小组。广泛的大圆和小圆分歧表明，在美国可能开始降解其动质体的菌株在非洲的多次引入事件的历史。