Multistep Track Segmentation and Motion Classification for Transient Mobility Analysis
Multistep Track Segmentation and Motion Classification for Transient Mobility Analysis
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DOI：
10.1016/j.bpj.2018.01.012
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发表时间：
2018-03-13
影响因子：
3.4
通讯作者：
Jaqaman, Khuloud
中科院分区：
文献类型：
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作者：
Vega, Anthony R.;Freeman, Spencer A.;Jaqaman, Khuloud
分子间的相互作用通常是短暂的，可能在观察窗口内发生变化，导致分子运动发生变化。因此，准确的运动分析通常需要瞬时运动分类。在这里，我们提出了一个准确的和计算效率的瞬态移动性分析框架，称为“分治矩标度谱”（DC-MSS）。DC-MSS以多步骤方式工作：1）其利用贯穿轨迹的局部运动描述符将其划分为不同运动类别的初始片段; 2）其经由分子位移的矩标度谱（MSS）分析对这些片段进行分类;以及3）其使用MSS分析结果来细化轨迹分割。该策略将运动开关的初始识别与运动分类分离，允许DC-MSS规避用于瞬态运动分析的经典滚动窗口方法的灵敏度-准确度权衡，同时利用MSS分析的分类能力。DC-MSS的测试表明，它检测自由扩散，受限扩散，定向扩散，和不动性之间的开关具有很高的灵敏度。为了说明DC-MSS的实用性，我们将其应用于巨噬细胞表面跨膜蛋白CD 44的单粒子轨道，揭示了肌动蛋白依赖性的瞬时迁移率变化。
Molecular interactions are often transient and might change within the window of observation, leading to changes in molecule movement. Therefore, accurate motion analysis often requires transient motion classification. Here we present an accurate and computationally efficient transient mobility analysis framework, termed "divide-and-conquer moment scaling spectrum" (DC-MSS). DC-MSS works in a multistep fashion: 1) it utilizes a local movement descriptor throughout a track to divide it into initial segments of putatively different motion classes; 2) it classifies these segments via moment scaling spectrum (MSS) analysis of molecule displacements; and 3) it uses the MSS analysis results to refine the track segmentation. This strategy uncouples the initial identification of motion switches from motion classification, allowing DC-MSS to circumvent the sensitivity -accuracy tradeoff of classic rolling window approaches for transient motion analysis, while at the same time harnessing the classification power of MSS analysis. Testing of DC-MSS demonstrates that it detects switches among free diffusion, confined diffusion, directed diffusion, and immobility with great sensitivity. To illustrate the utility of DC-MSS, we have applied it to single-particle tracks of the transmembrane protein CD44 on the surface of macrophages, revealing actin cortex-dependent transient mobility changes.