In experiments on mouse and human cells it was demonstrated that rDNA plays an important role in epigenetic regulation of many genes. To identify and study rDNA-contacting genes in Drosophila we used the 4С (circular chromosome conformation capture) approach. We detected very stable contacts of rDNA genes within a 5-kb region inside the Tlk gene residing in X chromosome. This 5-kb region corresponds to small RNAs. After heat shock treatment both the amount of contacts, and the expression level of the gene were increased. Tlk and Rala are genes that share the same short bidirectional promoter but exhibit different expression levels. Around the region of rDNA contacts inside the Tlk gene, looped domains were formed. We conclude that rDNA contact-dependent epigenetic regulation is guided by small RNAs and that the contacts are involved in rearrangements of the looped domains.

中文翻译：

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果蝇rDNA基因在小RNA的表达区域塑造与Tlk基因的稳定接触，并影响该基因内部的环状结构域

在小鼠和人类细胞的实验中，证明了rDNA在许多基因的表观遗传调控中起着重要作用。为了鉴定和研究果蝇中与rDNA接触的基因，我们使用了4С（圆形染色体构象捕获）方法。我们在X染色体上的Tlk基因内的5 kb区域内检测到非常稳定的rDNA基因接触。该5kb区域对应于小RNA。热激处理后，接触量和基因表达水平均增加。Tlk和Rala是共享相同的短双向启动子但显示不同表达水平的基因。Tlk内部的rDNA接触区域周围基因，形成环状结构域。我们得出的结论是，rDNA接触依赖的表观遗传调控是由小RNA指导的，并且接触参与了环结构域的重排。