ABSTRACT Chromatin ‘blobs’ were recently identified by live super-resolution imaging of labeled nucleosomes as pervasive but fleeting structural entities. However, the mechanisms leading to the formation of these blobs and their functional implications are unknown. We explore here whether causal relationships exist between parameters that characterize the chromatin blob dynamics and structure, by adapting a framework for spatio-temporal Granger-causality inference. Our analysis reveals that chromatin dynamics is a key determinant for both blob area and local density. Such causality, however, could be demonstrated only in 10–20% of the nucleus, suggesting that chromatin dynamics and structure at the nanometer scale are dominated by stochasticity. We show that the theory of active semiflexible polymers can be invoked to provide potential mechanisms leading to the organization of chromatin into blobs. Our results represent a first step toward elucidating the mechanisms that govern the dynamic and stochastic organization of chromatin in the cell nucleus.

中文翻译：

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动力学是基因组纳米级组织的原因

摘要染色质“斑点”最近通过标记核小体的实时超分辨率成像被鉴定为普遍存在但转瞬即逝的结构实体。然而，导致这些斑点形成的机制及其功能意义尚不清楚。我们在这里通过调整时空格兰杰因果关系推断的框架来探索表征染色质斑点动力学和结构的参数之间是否存在因果关系。我们的分析表明，染色质动力学是斑点面积和局部密度的关键决定因素。然而，这种因果关系只能在 10-20% 的细胞核中得到证实，这表明纳米尺度的染色质动力学和结构受随机性支配。我们表明，可以调用活性半柔性聚合物的理论来提供导致染色质组织成斑点的潜在机制。我们的结果代表了阐明控制细胞核中染色质动态和随机组织的机制的第一步。