Evolutionary origin of the medaka Y chromosome
Evolutionary origin of the medaka Y chromosome
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DOI：
10.1016/j.cub.2004.09.026
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发表时间：
2004-09-21
期刊：
影响因子：
9.2
通讯作者：
Schartl, M
中科院分区：
文献类型：
--
作者：
Kondo, M;Nanda, I;Schartl, M
XX-XY染色体系统中的遗传性别决定可以通过Y染色体上的一个位点来实现，该位点使未分化的性腺发育成睾丸。虽然这种机制是普遍的，只有在两个案例中，到目前为止，已确定相应的主男性性别决定基因。一种是Sry [1-5]，它在大多数哺乳动物中启动睾丸决定。另一个是dmrt 1 bY [6，7]（syn. dmy），来自青鳉（Oryzias latipes）。哺乳动物Y染色体的年龄估计超过2亿年[8]。青鳉Y可能相当年轻[6，9]。对Oryzias属的比较分析显示，青鳉的一个姐妹种在同源Y染色体上有dmrt 1bY，而在另一个密切相关的物种中，只有一个非性连锁的假基因存在。在所有其他物种中，未检测到dmrt 1bY。用线粒体DNA序列测定了不同种的分歧时间。通过基于dmrt 1序列的独立计算确认了时间。我们发现青鳉性别决定基因起源于大约1000万年前。这使得dmrt 1 bY和相应的Y染色体成为迄今为止已知的最年轻的男性性别决定系统，至少在脊椎动物中是这样。
Genetic sex determination in an XX-XY chromosome system can be realized through a locus on the Y chromosome that makes the undifferentiated gonad develop into a testis. Although this mechanism is widespread, only in two cases so far have the corresponding master male sex-determining genes been identified. One is Sry [1-5], which initiates testes determination in most mammals. The other is dmrt1 bY [6, 7] (syn. dmy), from the fish medaka, Oryzias latipes. The mammalian Y is roughly estimated to be over 200 million years old [8]. The medaka Y may be considerably younger [6, 9]. A comparative analysis of the genus Oryzias revealed that one sister species of the medaka has dmrt1bY on a homologous Y chromosome, whereas in another closely related species only a non-sex-linked pseudogene is present. In all other species, dmrt1bY was not detected. The divergence time for the different species was determined with mitochondrial DNA sequences. The timing was confirmed by independent calculations based on dmrt1 sequences. We show that the medaka sex-determining gene originated approximately 10 million years ago. This makes dmrt1 bY and the corresponding Y chromosome the youngest male sex-determining system, at least in vertebrates, known so far.