Enigma of Y chromosome degeneration:: Neo-Y and Neo-X chromosomes of Drosophila miranda a model for sex chromosome evolution
Enigma of Y chromosome degeneration:: Neo-Y and Neo-X chromosomes of Drosophila miranda a model for sex chromosome evolution
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DOI：
10.1023/a:1017058119760
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发表时间：
1998-01-01
期刊：
影响因子：
1.5
通讯作者：
Steinemann, S
中科院分区：
文献类型：
--
作者：
Steinemann, M;Steinemann, S
Y染色体变性的特征是染色体结构的改变和遗传惰性沿Y染色体的扩展。一般认为异型性染色体是由一对同源染色体发展而来的。人们提出了几种模式。我们利用果蝇第二性染色体对neo-Y和neo-X（X2）的独特情况，分析了Y染色体退化进化过程中涉及的分子机制。由于其中一条常染色体与Y染色体（约2 Mya）融合，形成了一条新Y染色体和一条新x染色体，称为X2。因此，以前的常染色体基因现在遗传在D. miranda的一对性染色体上。分析X2和neo-Y区域的DNA序列，我们观察到neo-Y染色体上大量的DNA插入。通过对几个插入元件的分析，我们提出了令人信服的证据，证明Y染色体变性的第一步是由转座元件，特别是反转录转座子的积累驱动的。在进化的Y染色体上，这些元素的富集可以解释染色质结构从正染色质转变为异染色质结构的原因。
Y chromosome degeneration is characterized by structural changes in the chromosome architecture and expansion of genetic inertness along the Y chromosome. It is generally assumed that the heteromorphic sex chromosome pair has developed from a pair of homologues. Several models have been suggested. We use the unique situation of the secondary sex chromosome pair, neo-Y and neo-X(X2), in Drosophila miranda to analyze molecular mechanisms involved in the evolutionary processes of Y chromosome degeneration. Due to the fusion of one of the autosomes to the Y chromosome (about 2 Mya), a neo-Y chromosome and a neo-X chromosome, designated X2, were formed. Thus, formerly autosomal genes are inherited now on a pair of sex chromosomes in D. miranda. Analyzing DNA sequences from the X2 and neo-Y region, we observed a massive accumulation of DNA insertions on the neo-Y chromosome. From the analysis of several insertion elements, we present compelling evidence that the first step in Y chromosome degeneration is driven by the accumulation of transposable elements, especially retrotransposons. An enrichment of these elements along an evolving Y chromosome could account for the switch from a euchromatic into a heterochromatic chromatin structure.