O'Connor Rebecca E, Kiazim Lucas, Skinner Ben, Fonseka Gothami, Joseph Sunitha, Jennings Rebecca, Larkin Denis M, Griffin Darren K
School of Biosciences, University of Kent, Canterbury, CT2 7NJ, UK. r.o'
School of Biosciences, University of Kent, Canterbury, CT2 7NJ, UK.
Chromosoma. 2019 Mar;128(1):21-29. doi: 10.1007/s00412-018-0685-6. Epub 2018 Nov 17.
The structure and organization of a species genome at a karyotypic level, and in interphase nuclei, have broad functional significance. Although regular sized chromosomes are studied extensively in this regard, microchromosomes, which are present in many terrestrial vertebrates, remain poorly explored. Birds have more cytologically indistinguishable microchromosomes (~ 30 pairs) than other vertebrates; however, the degree to which genome organization patterns at a karyotypic and interphase level differ between species is unknown. In species where microchromosomes have fused to other chromosomes, they retain genomic features such as gene density and GC content; however, the extent to which they retain a central nuclear position has not been investigated. In studying 22 avian species from 10 orders, we established that, other than in species where microchromosomal fusion is obvious (Falconiformes and Psittaciformes), there was no evidence of microchromosomal rearrangement, suggesting an evolutionarily stable avian genome (karyotypic) organization. Moreover, in species where microchromosomal fusion has occurred, they retain a central nuclear location, suggesting that the nuclear position of microchromosomes is a function of their genomic features rather than their physical size.
在核型水平以及间期细胞核中，一个物种基因组的结构与组织具有广泛的功能意义。尽管在这方面对常规大小的染色体已进行了广泛研究，但许多陆生脊椎动物中存在的微染色体却仍未得到充分探索。鸟类拥有比其他脊椎动物更多在细胞学上难以区分的微染色体（约30对）；然而，不同物种在核型和间期水平上基因组组织模式的差异程度尚不清楚。在微染色体已与其他染色体融合的物种中，它们保留了诸如基因密度和GC含量等基因组特征；然而，它们在细胞核中保持中心位置的程度尚未得到研究。在对来自10个目22种鸟类的研究中，我们确定，除了微染色体融合明显的物种（隼形目和鹦形目）外，没有微染色体重排的证据，这表明鸟类基因组（核型）组织在进化上是稳定的。此外，在发生微染色体融合的物种中，它们保留了细胞核中心位置，这表明微染色体的核位置是其基因组特征而非物理大小的函数。
