Anisotropic Material Properties of Wild-Type and Tectb-/- Tectorial Membranes.
Anisotropic Material Properties of Wild-Type and Tectb-/- Tectorial Membranes.
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DOI：
10.1016/j.bpj.2018.12.019
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发表时间：
2019-02
影响因子：
3.4
通讯作者：
Charlsie Lemons;J. Sellon;Elisa Boatti;Daniel Filizzola;D. M. Freeman;J. Meaud
中科院分区：
文献类型：
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作者：
Charlsie Lemons;J. Sellon;Elisa Boatti;Daniel Filizzola;D. M. Freeman;J. Meaud
覆膜（TM）是一种细胞外基质，直接与负责感觉转导和放大的机械电受体偶联。因此，TM通常被假设为在哺乳动物耳蜗的显着感觉能力中发挥关键作用。针对TM蛋白的遗传研究表明，TM结构的变化显着影响小鼠的耳蜗功能。需要关于野生型和突变小鼠TM在音频频率下的机械特性的精确信息来阐明TM的作用并了解这些基因突变如何影响耳蜗力学。在这项研究中，孤立的TM段的图像被用来确定响应于谐波径向激励的TM的径向和纵向运动。由此产生的纵向传播的径向位移和高度空间依赖的纵向位移建模使用有限元模型，考虑到各向异性和有限尺寸的TM。一个自动化的，最小二乘拟合算法被用来找到野生型和Tectb −/−小鼠在音频频率的各向异性材料特性。在听觉频率范围内，发现TM是一种高度粘弹性和各向异性的结构，在胶原纤维的方向上具有显著更高的刚度。虽然没有观察到纤维方向的刚度降低，但在Tectb −/−小鼠中发现TM在剪切和横向方向的刚度显著降低。因此，突变小鼠的TM在本研究中检查的频率范围内倾向于显著更各向异性。Tectb −/−突变对TM各向异性材料特性的影响可能是导致这些小鼠耳蜗调谐和灵敏度变化的原因。
The tectorial membrane (TM) is an extracellular matrix that is directly coupled with the mechanoelectrical receptors responsible for sensory transduction and amplification. As such, the TM is often hypothesized to play a key role in the remarkable sensory abilities of the mammalian cochlea. Genetic studies targeting TM proteins have shown that changes in TM structure dramatically affect cochlear function in mice. Precise information about the mechanical properties of the TMs of wild-type and mutant mice at audio frequencies is required to elucidate the role of the TM and to understand how these genetic mutations affect cochlear mechanics. In this study, images of isolated TM segments are used to determine both the radial and longitudinal motions of the TM in response to a harmonic radial excitation. The resulting longitudinally propagating radial displacement and highly spatially dependent longitudinal displacement are modeled using finite-element models that take into account the anisotropy and finite dimensions of TMs. An automated, least-square fitting algorithm is used to find the anisotropic material properties of wild-type andTectb−/−mice at audio frequencies. Within the auditory frequency range, it is found that the TM is a highly viscoelastic and anisotropic structure with significantly higher stiffness in the direction of the collagen fibers. Although no decrease in the stiffness in the fiber direction is observed, the stiffness of the TM in shear and in the transverse direction is found to be significantly reduced inTectb−/−mice. As a result, TMs of the mutant mice tend to be significantly more anisotropic within the frequency range examined in this study. The effects of theTectb−/−mutation on the TM's anisotropic material properties may be responsible for the changes in cochlear tuning and sensitivity that have been previously reported for these mice.