Bacterial chromosomal loci move subdiffusively through a viscoelastic cytoplasm.
Bacterial chromosomal loci move subdiffusively through a viscoelastic cytoplasm.
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DOI：
10.1103/physrevlett.104.238102
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发表时间：
2010-06-11
影响因子：
8.6
通讯作者：
Theriot JA
中科院分区：
文献类型：
--
作者：
Weber SC;Spakowitz AJ;Theriot JA
在活细菌细胞中追踪荧光标记的染色体基因座揭示了均方位移（MSD）的稳健缩放为τ0.39。布朗动力学模拟表明，这种异常行为不能完全占经典的劳斯或爬行模型的聚合物动力学。相反，所观察到的运动产生于细胞质的粘弹性环境内的DNA聚合物的劳斯模式的特征松弛。为了证明这些物理效应，我们利用我们的一般解析解的subdiffusive缩放嵌入在粘弹性介质中的聚合物中的单体。染色体位点的时间平均和整体平均MSD具有遍历性，在短时滞下速度自相关函数为负。这些观察结果与分数布朗运动最一致，并排除了连续时间随机行走模型作为体内异常运动的解释。
Tracking of fluorescently labeled chromosomal loci in live bacterial cells reveals a robust scaling of the mean square displacement (MSD) as τ0.39. Brownian dynamics simulations show that this anomalous behavior cannot be fully accounted for by the classic Rouse or reptation models for polymer dynamics. Instead, the observed motion arises from the characteristic relaxation of the Rouse modes of the DNA polymer within the viscoelastic environment of the cytoplasm. To demonstrate these physical effects, we exploit our general analytical solution of the subdiffusive scaling for a monomer in a polymer embedded in a viscoelastic medium. The time-averaged and ensemble-averaged MSD of chromosomal loci exhibit ergodicity, and the velocity autocorrelation function is negative at short time lags. These observations are most consistent with fractional Brownian motion and rule out a continuous time random walk model as an explanation for anomalous motion in vivo.