Institute of Human Genetics, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.
Sex Dev. 2011;5(5):266-71. doi: 10.1159/000331233. Epub 2011 Sep 13.
It was noted only recently that the mammalian X/Y sex chromosome system originated late in our therian ancestors. The question is, what makes the X/Y sex chromosome system so special that it has replaced the original Z/W sex chromosome system? Two classes of genes are overrepresented on the X chromosome: sex and reproduction genes and brain-related genes. The X chromosome has acquired bursts of young male-biased genes engaged in sex and reproduction which exemplifies the dynamics of sex chromosome evolution. Brain genes are old genes and display the most conserved transcriptome. The new therian X chromosome was formed by fusion of chromosome building blocks already bearing the highest density of brain genes in the ancestral vertebrate karyotype. These building blocks constitute an X chromosome haplotype that undergoes strong selection and benefits both sexes by oscillating between males and females. We believe that this strategy is superior to male-driven Z/W sex chromosome evolution.
最近有人指出，哺乳动物的 X/Y 性染色体系统是在我们的有胎盘类祖先中晚期起源的。问题是，是什么使得 X/Y 性染色体系统如此特别，以至于它取代了原来的 Z/W 性染色体系统？两类基因在 X 染色体上过度表达：性和生殖基因以及与大脑相关的基因。X 染色体获得了大量年轻的雄性偏向的性和生殖基因，这体现了性染色体进化的动态。大脑基因是古老的基因，表现出最保守的转录组。新的有胎盘类 X 染色体是由已经在祖先脊椎动物核型中带有最高密度大脑基因的染色体构建块融合形成的。这些构建块构成了一个 X 染色体单倍型，它通过在雄性和雌性之间振荡，受到强烈的选择，使两性都受益。我们相信，这种策略优于雄性驱动的 Z/W 性染色体进化。
