Zimmer Fabian, Harrison Peter W, Dessimoz Christophe, Mank Judith E
Department of Genetics Evolution and Environment, University College London, London, United Kingdom
Department of Genetics Evolution and Environment, University College London, London, United Kingdom.
Genome Biol Evol. 2016 Apr 25;8(4):1233-42. doi: 10.1093/gbe/evw075.
In many diploid species, sex determination is linked to a pair of sex chromosomes that evolved from a pair of autosomes. In these organisms, the degeneration of the sex-limited Y or W chromosome causes a reduction in gene dose in the heterogametic sex for X- or Z-linked genes. Variations in gene dose are detrimental for large chromosomal regions when they span dosage-sensitive genes, and many organisms were thought to evolve complete mechanisms of dosage compensation to mitigate this. However, the recent realization that a wide variety of organisms lack complete mechanisms of sex chromosome dosage compensation has presented a perplexing question: How do organisms with incomplete dosage compensation avoid deleterious effects of gene dose differences between the sexes? Here we use expression data from the chicken (Gallus gallus) to show that ohnologs, duplicated genes known to be dosage-sensitive, are preferentially dosage-compensated on the chicken Z chromosome. Our results indicate that even in the absence of a complete and chromosome wide dosage compensation mechanism, dosage-sensitive genes are effectively dosage compensated on the Z chromosome.
在许多二倍体物种中，性别决定与一对由常染色体进化而来的性染色体相关联。在这些生物中，性限制的Y或W染色体的退化导致异配性别中X或Z连锁基因的基因剂量减少。当基因剂量变化跨越剂量敏感基因时，对大的染色体区域是有害的，许多生物被认为进化出了完整的剂量补偿机制来减轻这种情况。然而，最近人们意识到，各种各样的生物缺乏完整的性染色体剂量补偿机制，这就提出了一个令人困惑的问题：具有不完全剂量补偿的生物如何避免两性之间基因剂量差异的有害影响？在这里，我们利用鸡（原鸡）的表达数据表明，已知对剂量敏感的重复基因——ohnologs，在鸡的Z染色体上优先进行剂量补偿。我们的结果表明，即使在没有完整的全染色体剂量补偿机制的情况下，剂量敏感基因在Z染色体上也能得到有效的剂量补偿。
