No evidence for a second evolutionary stratum during the early evolution of mammalian sex chromosomes.
No evidence for a second evolutionary stratum during the early evolution of mammalian sex chromosomes.
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DOI：
10.1371/journal.pone.0045488
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Satta Y
中科院分区：
文献类型：
--
作者：
Katsura Y;Satta Y
哺乳动物的性染色体起源于一对常染色体，性染色体上的同源基因（配子体）通过染色体间的重组阻滞而分化。据推测，真兽的这种分化是逐步发生的，并在X染色体上留下了一个足迹，称为“进化层”。进化层假说认为，第1层和第2层（对应于染色体分化的前两步）是在兽类的茎系中产生的，或者在真兽类和有袋类分化之前产生的。然而，这一预测仅仅依赖于人类配子学对之间的分子钟假说，而有袋动物性染色体基因的分子进化尚未得到研究。在本研究中，我们分析了以下7对有袋类配子学及其在第1层或第2层的同系物：SOX3/SRY、RBMX/Y、RPS4X/Y、HSFX/Y、XKRX/Y、SMCX/Y （KDM5C/D、JARID1C/D）和UBE1X/Y （UBA1/UBA1Y）。对这些配子学的系统发育分析和分化时间的估计表明，它们都是在兽类祖先中同时分化的。我们还提供了强有力的证据，证明基因转换发生在eutherian地层2基因（SMCX/Y和UBE1X/Y）的3 '区域。本研究结果表明：(1)没有令人信服的证据表明Theria的茎系中存在第二层；(2)在真动物谱系中，SMCX/Y和UBE1X/Y之间可能发生了基因转换，这可能是它们总体差异程度明显较低的原因。
Mammalian sex chromosomes originated from a pair of autosomes, and homologous genes on the sex chromosomes (gametologs) differentiated through recombination arrest between the chromosomes. It was hypothesized that this differentiation in eutherians took place in a stepwise fashion and left a footprint on the X chromosome termed “evolutionary strata.” The evolutionary stratum hypothesis claims that strata 1 and 2 (which correspond to the first two steps of chromosomal differentiation) were generated in the stem lineage of Theria or before the divergence between eutherians and marsupials. However, this prediction relied solely on the molecular clock hypothesis between pairs of human gametologs, and molecular evolution of marsupial sex chromosomal genes has not yet been investigated. In this study, we analyzed the following 7 pairs of marsupial gametologs, together with their eutherian orthologs that reside in stratum 1 or 2: SOX3/SRY, RBMX/Y, RPS4X/Y, HSFX/Y, XKRX/Y, SMCX/Y (KDM5C/D, JARID1C/D), and UBE1X/Y (UBA1/UBA1Y). Phylogenetic analyses and estimated divergence time of these gametologs reveal that they all differentiated at the same time in the therian ancestor. We have also provided strong evidence for gene conversion that occurred in the 3′ region of the eutherian stratum 2 genes (SMCX/Y and UBE1X/Y). The results of the present study show that (1) there is no compelling evidence for the second stratum in the stem lineage of Theria; (2) gene conversion, which may have occurred between SMCX/Y and UBE1X/Y in the eutherian lineage, potentially accounts for their apparently lower degree of overall divergence.
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DOI：
10.1098/rstb.2000.0717
发表时间：
2000-11-29
影响因子：
6.3
作者：
Charlesworth, B;Charlesworth, D
通讯作者：
Charlesworth, D
DOI：
10.1101/sqb.1987.052.01.094
发表时间：
1987-01-01
期刊：
COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY
影响因子：
--
作者：
MIYATA, T;HAYASHIDA, H;YASUNAGA, T
通讯作者：
YASUNAGA, T
影响因子：
7
作者：
Bhowmick, Bejon Kumar;Satta, Yoko;Takahata, Naoyuki
通讯作者：
Takahata, Naoyuki
DOI：
10.1073/pnas.0635848100
发表时间：
2003-04-29
影响因子：
11.1
作者：
Iwase, M;Satta, Y;Takahata, N
通讯作者：
Takahata, N
影响因子：
3.5
作者：
Mitchell, MJ;Wilcox, SA;Graves, JAM
通讯作者：
Graves, JAM