Arnold Arthur P, Itoh Yuichiro, Melamed Esther
Department of Physiological Science and Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, California 90095, USA.
Annu Rev Genomics Hum Genet. 2008;9:109-27. doi: 10.1146/annurev.genom.9.081307.164220.
Intensive study of a few genetically tractable species with XX/XY sex chromosomes has produced generalizations about the process of sex chromosome dosage compensation that do not fare well when applied to ZZ/ZW sex chromosome systems, such as those in birds. The inherent sexual imbalance in dose of sex chromosome genes has led to the evolution of sex-chromosome-wide mechanisms for balancing gene dosage between the sexes and relative to autosomal genes. Recent advances in our knowledge of avian genomes have led to a reexamination of sex-specific dosage compensation (SSDC) in birds, which is less effective than in known XX/XY systems. Insights about the mechanisms of SSDC in birds also suggest similarities to and differences from those in XX/XY species. Birds are thus offering new opportunities for studying dosage compensation in a ZZ/ZW system, which should shed light on the evolution of SSDC more broadly.
对少数具有XX/XY性染色体且易于进行遗传学研究的物种进行深入研究后，得出了一些关于性染色体剂量补偿过程的普遍结论，但这些结论应用于ZZ/ZW性染色体系统（如鸟类的性染色体系统）时效果不佳。性染色体基因剂量固有的性别失衡导致了全性染色体范围的机制进化，以平衡两性之间以及相对于常染色体基因的基因剂量。我们对鸟类基因组认识的最新进展促使人们重新审视鸟类的性别特异性剂量补偿（SSDC），这种补偿比已知的XX/XY系统中的补偿效率更低。对鸟类SSDC机制的深入了解也揭示了其与XX/XY物种的异同。因此，鸟类为研究ZZ/ZW系统中的剂量补偿提供了新机会，这将更广泛地阐明SSDC的进化过程。
