Kasai Fumio, O'Brien Patricia C M, Pereira Jorge C, Ferguson-Smith Malcolm A
Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
R Soc Open Sci. 2018 Aug 29;5(8):171539. doi: 10.1098/rsos.171539. eCollection 2018 Aug.
Extensive chromosome homologies revealed by cross-species chromosome painting between marsupials have suggested a high level of genome conservation during evolution. Surprisingly, it has been reported that marsupial genome sizes vary by more than 1.2 Gb between species. We have shown previously that individual chromosome sizes and GC content can be measured in flow karyotypes, and have applied this method to compare four marsupial species. Chromosome sizes and GC content were calculated for the grey short-tailed opossum (2 = 18), tammar wallaby (2 = 16), Tasmanian devil (2 = 14) and fat-tailed dunnart (2 = 14), resulting in genome sizes of 3.41, 3.31, 3.17 and 3.25 Gb, respectively. The findings under the same conditions allow a comparison between the four species, indicating that the genomes of these four species are 1-8% larger than human. We show that marsupial genomes are characterized by a low GC content invariable between autosomes and distinct from the higher GC content of the marsupial × chromosome.
有袋类动物之间通过跨物种染色体涂染揭示的广泛染色体同源性表明，在进化过程中基因组具有高度的保守性。令人惊讶的是，据报道，不同物种的有袋类动物基因组大小相差超过1.2 Gb。我们之前已经表明，可以在流式核型中测量单个染色体的大小和GC含量，并已应用该方法比较了四种有袋类动物。计算了灰短尾负鼠（2n = 18）、帚尾袋貂（2n = 16）、袋獾（2n = 14）和肥尾袋鼩（2n = 14）的染色体大小和GC含量，其基因组大小分别为3.41、3.31、3.17和3.25 Gb。在相同条件下的研究结果使得可以对这四个物种进行比较，表明这四个物种的基因组比人类基因组大1 - 8%。我们发现，有袋类动物基因组的特征是常染色体间GC含量较低且恒定，与有袋类动物X染色体较高的GC含量不同。
