Departamento de Genética, Facultad de Biología, Universidad Complutense, C/José Antonio Nováis 12, 28040 Madrid, Spain.
Planta. 2013 Jul;238(1):23-33. doi: 10.1007/s00425-013-1885-1. Epub 2013 Apr 27.
Different histone modifications often modify DNA-histone interactions affecting both local and global structure of chromatin, thereby providing a vast potential for functional responses. Most studies have focused on the role of several modifications in gene transcription regulation, being scarce on other aspects of eukaryotic chromosome structure during cell division, mainly in meiosis. To solve this issue we have performed a cytological analysis to determine the chromosomal distribution of several histone H3 modifications throughout all phases of both mitosis and meiosis in different plant species. We have chosen Aegilops sp. and Secale cereale (monocots) and Arabidopsis thaliana (dicots) because they differ in their phylogenetic affiliation as well as in content and distribution of constitutive heterochromatin. In the species analyzed, the patterns of H3 acetylation and methylation were held constant through mitosis, including modifications associated with "open chromatin". Likewise, the immunolabeling patterns of H3 methylation remained invariable throughout meiosis in all cases. On the contrary, there was a total loss of acetylated H3 immunosignals on condensed chromosomes in both meiotic divisions, but only in monocot species. Regarding the phosphorylation of histone H3 at Ser10, present on condensed chromosomes, although we did not observe any difference in the dynamics, we found slight differences between the chromosomal distribution of this modification between Arabidopsis and cereals (Aegilops sp. and rye). Thus far, in plants chromosome condensation throughout cell division appears to be associated with a particular combination of H3 modifications. Moreover, the distribution and dynamics of these modifications seem to be species-specific and even differ between mitosis and meiosis in the same species.
不同的组蛋白修饰通常会改变 DNA-组蛋白相互作用，影响染色质的局部和整体结构，从而为功能反应提供巨大的潜力。大多数研究都集中在几种修饰在基因转录调控中的作用上，而在细胞分裂过程中真核染色体结构的其他方面，主要是在减数分裂中，研究却很少。为了解决这个问题，我们进行了细胞学分析，以确定几种组蛋白 H3 修饰在不同植物物种的有丝分裂和减数分裂的所有阶段在染色体上的分布。我们选择了黑麦山羊草（单子叶植物）和普通小麦（单子叶植物）以及拟南芥（双子叶植物），因为它们在系统发育上的亲缘关系、组成性异染色质的含量和分布上存在差异。在所分析的物种中，H3 乙酰化和甲基化的模式在有丝分裂过程中保持不变，包括与“开放染色质”相关的修饰。同样，在所有情况下，H3 甲基化的免疫标记模式在减数分裂过程中保持不变。相反，在有丝分裂和减数分裂的所有阶段，在浓缩的染色体上，乙酰化的 H3 免疫信号完全丢失，但仅在单子叶植物中丢失。关于组蛋白 H3 在 Ser10 位的磷酸化，存在于浓缩的染色体上，虽然我们没有观察到动力学上的任何差异，但我们发现了这种修饰在拟南芥和谷类植物（黑麦山羊草和黑麦）之间在染色体分布上的细微差异。到目前为止，在植物细胞分裂过程中染色体的浓缩似乎与 H3 修饰的特定组合有关。此外，这些修饰的分布和动态似乎是物种特异性的，甚至在同一物种的有丝分裂和减数分裂之间也存在差异。
