RESUMO
The donkey, like the horse, is a promising model for exploring karyotypic instability. We report the de novo whole-genome assemblies of the donkey and the Asiatic wild ass. Our results reflect the distinct characteristics of donkeys, including more effective energy metabolism and better immunity than horses. The donkey shows a steady demographic trajectory. We detected abundant satellite sequences in some inactive centromere regions but not in neocentromere regions, while ribosomal RNAs frequently emerged in neocentromere regions but not in the obsolete centromere regions. Expanded miRNA families and five newly discovered miRNA target genes involved in meiosis may be associated with fast karyotype evolution. APC/C, controlling sister chromatid segregation, cytokinesis, and the establishment of the G1 cell cycle phase were identified by analysis of miRNA targets and rapidly evolving genes.
Assuntos
Equidae/genética , Evolução Molecular , Genoma , Impressão Genômica , Cariótipo , Animais , Centrômero/genética , Biologia Computacional/métodos , Rearranjo Gênico , Genômica/métodos , MicroRNAs/genética , Anotação de Sequência Molecular , Interferência de RNA , RNA Mensageiro/genética , Sequências Repetitivas de Ácido NucleicoRESUMO
Karyotypic diversification is more prominent in Equus species than in other mammals. Here, using next generation sequencing technology, we generated and de novo assembled quality genomes sequences for a male wild horse (Przewalski's horse) and a male domestic horse (Mongolian horse), with about 93-fold and 91-fold coverage, respectively. Portion of Y chromosome from wild horse assemblies (3â M bp) and Mongolian horse (2â M bp) were also sequenced and de novo assembled. We confirmed a Robertsonian translocation event through the wild horse's chromosomes 23 and 24, which contained sequences that were highly homologous with those on the domestic horse's chromosome 5. The four main types of rearrangement, insertion of unknown origin, inserted duplication, inversion, and relocation, are not evenly distributed on all the chromosomes, and some chromosomes, such as the X chromosome, contain more rearrangements than others, and the number of inversions is far less than the number of insertions and relocations in the horse genome. Furthermore, we discovered the percentages of LINE_L1 and LTR_ERV1 are significantly increased in rearrangement regions. The analysis results of the two representative Equus species genomes improved our knowledge of Equus chromosome rearrangement and karyotype evolution.