Topologically associating domains (TADs) are fundamental elements of the eukaryotic genomic structure. However, recent studies suggest that the insulating complexes, CTCF/cohesin, present at TAD borders in mammals are absent from those in Drosophila melanogaster, raising the possibility that border elements are not conserved among metazoans. Using in situ Hi-C with sub-kb resolution, here we show that the D. melanogaster genome is almost completely partitioned into >4000 TADs, nearly sevenfold more than previously identified. The overwhelming majority of these TADs are demarcated by the insulator complexes, BEAF-32/CP190, or BEAF-32/Chromator, indicating that these proteins may play an analogous role in flies as that of CTCF/cohesin in mammals. Moreover, extended regions previously thought to be unstructured are shown to consist of small contiguous TADs, a property also observed in mammals upon re-examination. Altogether, our work demonstrates that fundamental features associated with the higher-order folding of the genome are conserved from insects to mammals.

中文翻译：

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黑腹果蝇中的亚 kb Hi-C 揭示了昆虫和哺乳动物细胞之间 TAD 的保守特征。


拓扑关联结构域（TAD）是真核基因组结构的基本元素。然而，最近的研究表明，存在于哺乳动物 TAD 边界的绝缘复合物 CTCF/粘连蛋白在果蝇中不存在，这增加了边界元件在后生动物中不保守的可能性。使用亚 kb 分辨率的原位 Hi-C，我们发现黑腹果蝇基因组几乎完全划分为 >4000 个 TAD，比之前识别的多近七倍。这些 TAD 中的绝大多数由绝缘体复合物 BEAF-32/CP190 或 BEAF-32/Chromator 划分，表明这些蛋白质在果蝇中可能发挥与哺乳动物中 CTCF/粘连蛋白类似的作用。此外，以前被认为是非结构化的延伸区域被证明是由小的连续 TAD 组成，在重新检查时在哺乳动物中也观察到了这一特性。总而言之，我们的工作表明，与基因组高阶折叠相关的基本特征从昆虫到哺乳动物都是保守的。