Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, Russia.
Institute of Mathematical Problems of Biology RAS-The Branch of Keldysh Institute of Applied Mathematics of Russian Academy of Sciences, Pushchino, Russia.
BMC Evol Biol. 2020 Dec 11;20(1):164. doi: 10.1186/s12862-020-01726-0.
Eukaryotic protein-coding genes consist of exons and introns. Exon-intron borders are conserved between species and thus their changes might be observed only on quite long evolutionary distances. One of the rarest types of change, in which intron relocates over a short distance, is called "intron sliding", but the reality of this event has been debated for a long time. The main idea of a search for intron sliding is to use the most accurate genome annotation and genome sequence, as well as high-quality transcriptome data. We applied them in a search for sliding introns in mammals in order to widen knowledge about the presence or absence of such phenomena in this group.
We didn't find any significant evidence of intron sliding in the primate group (human, chimpanzee, rhesus macaque, crab-eating macaque, green monkey, marmoset). Only one possible intron sliding event supported by a set of high quality transcriptomes was observed between EIF1AX human and sheep gene orthologs. Also, we checked a list of previously observed intron sliding events in mammals and showed that most likely they are artifacts of genome annotations and are not shown in subsequent annotation versions as well as are not supported by transcriptomic data.
We assume that intron sliding is indeed a very rare evolutionary event if it exists at all. Every case of intron sliding needs a lot of supportive data for detection and confirmation.
真核生物的蛋白质编码基因由外显子和内含子组成。exon-intron 边界在物种间是保守的，因此它们的变化只能在相当长的进化距离上观察到。exon-intron 边界在物种间是保守的，因此它们的变化只能在相当长的进化距离上观察到。一种罕见的变化类型是，内含子在短距离内重新定位，这种变化类型被称为“内含子滑动”，但这种事件的真实性长期以来一直存在争议。寻找内含子滑动的主要想法是使用最准确的基因组注释和基因组序列，以及高质量的转录组数据。我们将这些应用于哺乳动物中滑动内含子的搜索，以扩大对该组中存在或不存在此类现象的认识。
我们在灵长类动物（人类、黑猩猩、恒河猴、食蟹猴、绿猴、狨猴）中没有发现任何内含子滑动的显著证据。只在人类和绵羊基因直系同源物之间观察到一个可能的内含子滑动事件，该事件得到了一组高质量转录组的支持。此外，我们还检查了哺乳动物中以前观察到的内含子滑动事件列表，并表明它们很可能是基因组注释的人工制品，在随后的注释版本中不再显示，也没有转录组数据支持。
我们假设，如果内含子滑动确实存在，它也是一种非常罕见的进化事件。每个内含子滑动的情况都需要大量的支持数据来检测和确认。
