Biomechanics and Modeling in Mechanobiology ( IF 3.5 ) Pub Date : 2021-08-24 , DOI: 10.1007/s10237-021-01507-8 Eashan Saikia 1 , Nino F Läubli 2, 3 , Hannes Vogler 4 , Markus Rüggeberg 5 , Hans J Herrmann 6 , Ingo Burgert 1, 7 , Jan T Burri 2 , Bradley J Nelson 2 , Ueli Grossniklaus 4 , Falk K Wittel 1
The sensory hairs of the Venus flytrap (Dionaea muscipula Ellis) detect mechanical stimuli imparted by their prey and fire bursts of electrical signals called action potentials (APs). APs are elicited when the hairs are sufficiently stimulated and two consecutive APs can trigger closure of the trap. Earlier experiments have identified thresholds for the relevant stimulus parameters, namely the angular displacement \(\theta \) and angular velocity \(\omega \). However, these experiments could not trace the deformation of the trigger hair’s sensory cells, which are known to transduce the mechanical stimulus. To understand the kinematics at the cellular level, we investigate the role of two relevant mechanical phenomena: viscoelasticity and intercellular fluid transport using a multi-scale numerical model of the sensory hair. We hypothesize that the combined influence of these two phenomena and \(\omega \) contribute to the flytrap’s rate-dependent response to stimuli. In this study, we firstly perform sustained deflection tests on the hair to estimate the viscoelastic material properties of the tissue. Thereafter, through simulations of hair deflection tests at different loading rates, we were able to establish a multi-scale kinematic link between \(\omega \) and the cell wall stretch \(\delta \). Furthermore, we find that the rate at which \(\delta \) evolves during a stimulus is also proportional to \(\omega \). This suggests that mechanosensitive ion channels, expected to be stretch-activated and localized in the plasma membrane of the sensory cells, could be additionally sensitive to the rate at which stretch is applied.
中文翻译:
促成捕蝇草对刺激的速率依赖性反应的机械因素
捕蝇草 ( Dionaea muscipula Ellis)的感觉毛可检测猎物传递的机械刺激和称为动作电位 (AP) 的电信号的爆发。当毛发受到充分刺激时会引发 AP,并且两个连续的 AP 可以触发陷阱的关闭。早期的实验已经确定了相关刺激参数的阈值,即角位移\(\theta \)和角速度\(\omega \). 然而,这些实验无法追踪触发毛发的感觉细胞的变形,已知这些细胞可以传导机械刺激。为了了解细胞水平的运动学,我们使用感觉毛发的多尺度数值模型研究了两种相关机械现象的作用:粘弹性和细胞间流体输送。我们假设这两种现象的综合影响和\(\omega \)有助于捕蝇器对刺激的速率依赖性反应。在这项研究中,我们首先对头发进行持续偏转测试,以估计组织的粘弹性材料特性。此后,通过模拟不同加载速率下的头发变形测试,我们能够建立多尺度运动学联系\(\omega \)和细胞壁拉伸\(\delta \)。此外,我们发现\(\delta \)在刺激期间的演变速率也与\(\omega \)成正比。这表明机械敏感离子通道,预计将被拉伸激活并定位在感觉细胞的质膜中,可能对施加拉伸的速率额外敏感。