Chromosome and DNA methylation dynamics during meiosis in the autotetraploid Arabidopsis arenosa
Chromosome and DNA methylation dynamics during meiosis in the autotetraploid Arabidopsis arenosa
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DOI：
10.1007/s00497-009-0115-2
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发表时间：
2010-03-01
影响因子：
--
通讯作者：
Neves, Nuno
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文献类型：
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作者：
Carvalho, Ana;Delgado, Margarida;Neves, Nuno
多倍体引起的染色体数目变化会严重损害减数分裂的稳定性。在同源多倍体中，两个以上同源染色体的存在可能导致复杂的配对模式和随后的异常染色体分离。在此背景下，研究了天然同源四倍体拟南芥中的染色中心、着丝粒、端粒和核糖体 DNA 基因座拓扑和 DNA 甲基化模式。数据显示，同源染色体识别和关联始于减数分裂前间期的端粒结构域，随后在细线期核糖体 45S RNA 基因位点（称为 NOR）进行四价配对。另一方面，细线早期的着丝粒区域显示出成对关联，而不是四对关联。这些成对关联在整个前期 I 中保持不变，因此可能与 A. arenosa 染色体在中期 I 的二倍体样行为有关，其中仅观察到二价体。在花药中，体细胞间期和减数分裂前间期的细胞均显示 5-甲基胞嘧啶 (5-mC) 分散在整个细胞核中，这与在营养细胞核中观察到的与染色中心的优先共定位形成对比。这些结果首次表明，5-mC 的核分布模式在性母细胞和花药体细胞中同时重新洗牌。在前期 I 期间，在延伸的染色质纤维和染色中心中检测到 5-mC，但有趣的是，它被排除在与配对模式相关的 NOR 之外。
Variation in chromosome number due to polyploidy can seriously compromise meiotic stability. In autopolyploids, the presence of more than two homologous chromosomes may result in complex pairing patterns and subsequent anomalous chromosome segregation. In this context, chromocenter, centromeric, telomeric and ribosomal DNA locus topology and DNA methylation patterns were investigated in the natural autotetraploid, Arabidopsis arenosa. The data show that homologous chromosome recognition and association initiates at telomeric domains in premeiotic interphase, followed by quadrivalent pairing of ribosomal 45S RNA gene loci (known as NORs) at leptotene. On the other hand, centromeric regions at early leptotene show pairwise associations rather than associations in fours. These pairwise associations are maintained throughout prophase I, and therefore likely to be related to the diploid-like behavior of A. arenosa chromosomes at metaphase I, where only bivalents are observed. In anthers, both cells at somatic interphase as well as at premeiotic interphase show 5-methylcytosine (5-mC) dispersed throughout the nucleus, contrasting with a preferential co-localization with chromocenters observed in vegetative nuclei. These results show for the first time that nuclear distribution patterns of 5-mC are simultaneously reshuffled in meiocytes and anther somatic cells. During prophase I, 5-mC is detected in extended chromatin fibers and chromocenters but interestingly is excluded from the NORs what correlates with the pairing pattern.