Dichotomy of Dosage Compensation along the Neo Z Chromosome of the Monarch Butterfly
Dichotomy of Dosage Compensation along the Neo Z Chromosome of the Monarch Butterfly
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DOI：
10.1016/j.cub.2019.09.056
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发表时间：
2019-12-02
期刊：
影响因子：
9.2
通讯作者：
Walters, James R.
中科院分区：
文献类型：
--
作者：
Gu, Liuqi;Reilly, Patrick F.;Walters, James R.
性染色体剂量补偿（SCDC）的机制在动物中有很大的不同。在果蝇中，半合子（XY）雄性中的染色体范围转录是单个X染色体的两倍，而在隐杆线虫中，纯合（XX）雌性中的两个X拷贝的表达减半[1，2]。与其他雌性异配子（WZ雌性和ZZ雄性）动物不同，蛾和蝴蝶表现出通常仅在雄性异配子物种中观察到的性染色体剂量补偿模式[3]。帝王蝶携带一个新衍生的Z染色体片段，该片段来自与祖先Z的常染色体融合[4]。使用一个高度连续的基因组组装，我们表明，基因表达是平衡的性别之间沿着整个Z染色体，但具有不同的模式的补偿的两个部分。在祖先的Z区段上，H4K16ac的耗尽对应于雄性中双等位基因转录的几乎减半，这是一种收敛于线虫的模式。相反，新衍生的Z段显示出果蝇样的补偿模式，与丰富的H4K16ac水平对应于双单等位基因转录的女性。我们的工作表明，相反的期望，增选调节机制容易到位，剂量补偿的多种模式的演变也是可能的沿着一个单一的性染色体在一个物种。
Mechanisms of sex chromosome dosage compensation (SCDC) differ strikingly among animals. In Drosophila flies, chromosome-wide transcription is doubled from the single X chromosome in hemizygous (XY) males, whereas in Caenorhabditis nematodes, expression is halved for both X copies in homozygous (XX) females [1, 2]. Unlike other female-heterogametic (WZ female and ZZ male) animals, moths and butterflies exhibit sex chromosome dosage compensation patterns typically seen only in male-heterogametic species [3]. The monarch butterfly carries a newly derived Z chromosome segment that arose from an autosomal fusion with the ancestral Z [4]. Using a highly contiguous genome assembly, we show that gene expression is balanced between sexes along the entire Z chromosome but with distinct modes of compensation on the two segments. On the ancestral Z segment, depletion of H4K16ac corresponds to nearly halving of biallelic transcription in males, a pattern convergent to nematodes. Conversely, the newly derived Z segment shows a Drosophila-like mode of compensation, with enriched H4K16ac levels corresponding to doubled monoallelic transcription in females. Our work reveals that, contrary to the expectation of co-opting regulatory mechanisms readily in place, the evolution of plural modes of dosage compensation is also possible along a single sex chromosome within a species.