Arrangement of radial actin bundles in the growth cone of Aplysia bag cell neurons shows the immediate past history of filopodial behavior
Arrangement of radial actin bundles in the growth cone of Aplysia bag cell neurons shows the immediate past history of filopodial behavior
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DOI：
10.1073/pnas.96.14.7928
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发表时间：
1999-07-06
影响因子：
11.1
通讯作者：
Oldenbourg, R
中科院分区：
文献类型：
--
作者：
Katoh, K;Hammar, K;Oldenbourg, R
位于神经生长锥前缘的丝状伪足从板状伪足向前突出，用于引导神经细胞的延伸。在每个丝状伪足的核心处，形成肌动蛋白束并生长成板状伪足。通过使用时间推移偏振光图像的kymographs，我们研究的行为之间的关系的丝状伪足，肌动蛋白束紧邻丝状伪足，和肌动蛋白束的形状和组成在整个板状伪足。我们发现，肌动蛋白束的形状，如倾斜，叉，融合区，起源于前缘，并令人惊讶地保存完好，在整个板状伪足的肌动蛋白细胞骨架的逆行运输过程中。由其双折射延迟显示的构成径向肌动蛋白束的细丝的数量，在从前缘到板状伪足的4-8 μ m的距离上的逆行流动期间也被保留。因此，在任何时间点冷冻的板状伪足中肌动蛋白束的处置保存并描绘了丝状伪足附近肌动蛋白束的过去行为和丝状伪足本身的行为的历史。这些发现表明，静态图像记录中肌动蛋白束的排列，如固定和染色标本的电子或荧光显微照片，实际上可以揭示丝状伪足行为过去历史的顺序以及肌动蛋白束中丝状体的产生、密度、融合等。
Filopodia that protrude forward from the lamellipodium, located at the leading edge of a neuronal growth cone, are needed to guide the extension of a nerve cell. At the core of each filopodium an actin bundle forms and grows into the lamellipodium. By using kymographs of time-lapse polarized light images we examined the relationship between the behavior of the filopodia, the actin bundles immediately proximal to the filopodia, and the shapes and composition of actin bundles in the whole lamellipodium. We find that the shapes of actin bundles, such as tilt, fork, and fused zones, originate at the leading edge and are surprisingly well preserved during retrograde transport of the actin cytoskeleton in the whole lamellipodium. The number of filaments that make up the radial actin bundles, as displayed by their birefringence retardation, also is preserved during retrograde flow over a distance of 4-8 mu m from the leading edge into the lamellipodium. Thus, the disposition of the actin bundles in the lamellipodium frozen at any time point preserves and portrays a history of the past behavior of actin bundles proximal to the filopodia and the behavior of the filopodia themselves. These findings suggest that the arrangement of actin bundles in static image records, such as electron or fluorescence micrographs of fixed and stained specimens, can in fact reveal the sequence of the past history of filopodial behavior and the generation, density, fusion, etc. of the filaments in the actin bundles.