Fornaini Nicola R, Bergelová Barbora, Gvoždík Václav, Černohorská Halina, Krylov Vladimír, Kubíčková Svatava, Fokam Eric B, Badjedjea Gabriel, Evans Ben J, Knytl Martin
Department of Cell Biology, Faculty of Science, Charles University, Viničná 7, Prague, 12843 Czech Republic.
Institute of Vertebrate Biology of the Czech Academy of Sciences, Brno, Czech Republic.
Eur J Wildl Res. 2023;69(4):81. doi: 10.1007/s10344-023-01709-8. Epub 2023 Jul 21.
Repetitive elements have been identified in several amphibian genomes using whole genome sequencing, but few studies have used cytogenetic mapping to visualize these elements in this vertebrate group. Here, we used fluorescence in situ hybridization and genomic data to map the U1 and U2 small nuclear RNAs and histone H3 in six species of African clawed frog (genus ), including, from subgenus , the diploid and its close allotetraploid relative and, from subgenus , the allotetraploid species , , , and . Results allowed us to qualitatively evaluate the relative roles of polyploidization and divergence in the evolution of repetitive elements because our focal species include allotetraploid species derived from two independent polyploidization events - one that is relatively young that gave rise to and another that is older that gave rise to the other (older) allotetraploids. Our results demonstrated conserved loci number and position of signals in the species from subgenus ; allotetraploid has twice as many signals as diploid . However, the content of repeats varied among the other allotetraploid species. We detected almost same number of signals in as in and same number of signals in , , as in the diploid . Overall, these results are consistent with the proposal that allopolyploidization duplicated these tandem repeats and that variation in their copy number was accumulated over time through reduction and expansion in a subset of the older allopolyploids.
利用全基因组测序技术，在几种两栖动物基因组中已鉴定出重复元件，但很少有研究使用细胞遗传学图谱来在这个脊椎动物类群中可视化这些元件。在这里，我们使用荧光原位杂交和基因组数据，对六种非洲爪蟾（ 属）中的U1和U2小核RNA以及组蛋白H3进行图谱绘制，其中包括来自 亚属的二倍体 及其亲缘关系密切的异源四倍体 ，以及来自 亚属的异源四倍体物种 、 、 和 。我们的研究结果使我们能够定性评估多倍体化和分化在重复元件进化中的相对作用，因为我们所关注的物种包括源自两个独立多倍体化事件的异源四倍体物种——一个相对较新的事件产生了 ，另一个较古老的事件产生了其他（更古老的）异源四倍体。我们的结果表明， 亚属物种中信号的位点数量和位置是保守的；异源四倍体 的信号数量是二倍体 的两倍。然而，其他异源四倍体物种的重复序列含量有所不同。我们在 中检测到的信号数量与在 中几乎相同，在 、 、 中检测到的信号数量与二倍体 中的相同。总体而言，这些结果与以下观点一致：异源多倍体化使这些串联重复序列加倍，并且随着时间的推移，在一部分较古老的异源多倍体中，通过减少和扩增，它们的拷贝数发生了变化。
