Polyploid species represent a challenge for both cytogenetic and genomic studies due to their high chromosome numbers and the morphological similarity between their paralogous chromosomes. This paper describes the use of low-coverage high-throughput sequencing to identify the 14 most abundant tandemly arranged repetitive elements in the paleotetraploid genome of the crucian carp (Carassius carassius, 2n = 100). These repetitive elements were then used for molecular cytogenetic studies of a closely related functionally triploid form of the Prussian carp (Carassius gibelio, 3n = 150 + Bs) and a relatively distant diploid species, the tench (Tinca tinca, 2n = 48). According to their distribution on the chromosomes of the 3 aforementioned species, the repetitive elements here identified can be divided into 5 groups: (1) those specific to a single genomic locus in both Carassius species, despite the recent carp-specific genome duplication; (2) those located in a single genomic locus of T. tinca, but amplified in one or both Carassius species; (3) those massively amplified in the B chromosomes of C. gibelio; (4) those located in a single locus in C. gibelio, but amplified in many blocks in C. carassius; and (5) those located in multiple pericentromeric loci in both Carassius species. Our data indicate that some of the repetitive elements are highly conserved in cyprinoid species and may serve as good cytogenetic and genomic markers for discriminating paralogous chromosomes, while others are evolutionarily recent, and their amplification may be related to the last whole-genome duplication event.
Cytogenet Genome Res

中文翻译：

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不同倍性水平的3种鲤科动物串联排列的重复DNA的进化

多倍体物种由于其高染色体数和其旁系染色体之间的形态相似性，对细胞遗传学和基因组学研究都构成了挑战。本文介绍了使用低覆盖率高通量测序来鉴定cru的古四倍体基因组中14个最丰富的串联排列的重复元件（Carassius carassius，2n = 100）。然后将这些重复元件用于普鲁士鲤鱼（Carassius gibelio， 3n = 150 + Bs）和相对较远的二倍体物种the（Tinca tinca）的功能上密切相关的三倍体形式的分子细胞遗传学研究。，2n = 48）。根据它们在上述3个物种的染色体上的分布，此处确定的重复元件可分为5组：（1）尽管最近有鲤鱼特异性基因组重复，但在两个Car鱼物种中对单个基因组位点具有特异性的那些元素；（2）位于丁香天蛾一个基因组位点，但在一种或两种Car鱼物种中扩增的那些；（3）那些的乙染色体大规模扩增C.鲫; （4）位于C. gibelio的单个基因座，但在C. carassius的许多区块中扩增的那些；和（5）是位于在两个多基因座近着丝粒鲫鱼物种。我们的数据表明，某些重复元件在类赛璐oid物种中高度保守，可作为区分旁系染色体的良好细胞遗传学和基因组标志物，而其他则是进化上最近的，其扩增可能与最后一个全基因组复制事件有关。
细胞遗传学基因组研究