The rRNA genes of mouse and human encode the three major RNAs of the ribosome and as such are essential for growth and development. These genes are present in high copy numbers and arranged as direct repeats at the Nucleolar Organizer Regions on multiple chromosomes. Not all the rRNA genes are transcriptionally active, but the molecular mechanisms that determine activity are complex and still poorly understood. Recent studies applying a novel Deconvolution Chromatin Immunoprecipitation (DChIP-Seq) technique in conjunction with conditional gene inactivation provide new insights into the structure of the active rRNA genes and question previous assumptions on the role of chromatin and histone modifications. We suggest an alternative model for the active rRNA gene chromatin and discuss how this structure is determined and maintained.

中文翻译：

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小鼠和人类中核糖体RNA基因的染色质景观。

小鼠和人的rRNA基因编码核糖体的三个主要RNA，因此对于生长和发育至关重要。这些基因以高拷贝数存在，并以直接重复的形式排列在多条染色体的核仁组织区。并非所有的rRNA基因都具有转录活性，但是决定活性的分子机制是复杂的，但仍知之甚少。最近将新颖的去卷积染色质免疫沉淀（DChIP-Seq）技术与条件基因失活结合使用的研究为活性rRNA基因的结构提供了新见识，并对先前关于染色质和组蛋白修饰的假设提出了质疑。我们建议活性rRNA基因染色质的替代模型，并讨论如何确定和维持这种结构。