Power-limited contraction dynamics of Vorticella convallaria: an ultrafast biological spring.
Power-limited contraction dynamics of Vorticella convallaria: an ultrafast biological spring.
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Vorticella convallaria 的功率限制收缩动力学：超快生物弹簧。
DOI：
10.1529/biophysj.107.108852
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发表时间：
2008
影响因子：
3.4
通讯作者：
L. Mahadevan
中科院分区：
文献类型：
--
作者：
A. Upadhyaya;M. Baraban;J. Wong;P. Matsudaira;A. van Oudenaarden;L. Mahadevan
卷曲霉是最快、最强大的细胞机之一。细胞体通过一根细长的柄附着在底物上，其中包含一种聚合结构--痉挛。茎的螺旋卷曲是由痉挛蛋白的快速收缩引起的，这一事件是由钙与带负电的聚合物主干结合所介导的。我们使用高速成像来测量收缩速度作为外部环境粘度的函数，发现最大速度与粘度的平方根成反比。如果收缩速度最终受到主动收缩痉挛所传递的力量的限制，就可以解释这一点。在微观上，如果沿着痉挛蛋白传播的机械力化学波的速度快于细胞体由于其巨大的流体动力阻力而能够做出反应的速度，就会出现这种情况。我们通过使用珠子作为柄上的标记来证实这一点，并发现收缩始于细胞体，并以超过细胞体速度的速度沿着柄进行。
Vorticella convallaria is one of the fastest and most powerful cellular machines. The cell body is attached to a substrate by a slender stalk containing a polymeric structure-the spasmoneme. Helical coiling of the stalk results from rapid contraction of the spasmoneme, an event mediated by calcium binding to a negatively charged polymeric backbone. We use high speed imaging to measure the contraction velocity as a function of the viscosity of the external environment and find that the maximum velocity scales inversely with the square root of the viscosity. This can be explained if the rate of contraction is ultimately limited by the power delivered by the actively contracting spasmoneme. Microscopically, this scenario would arise if the mechanochemical wave that propagates along the spasmoneme is faster than the rate at which the cell body can respond due to its large hydrodynamic resistance. We corroborate this by using beads as markers on the stalk and find that the contraction starts at the cell body and proceeds down the stalk at a speed that exceeds the velocity of the cell body.