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首页> 外文期刊>Journal of Biomechanics >Analysis of the flow field induced by the sessile peritrichous ciliate Opercularia asymmetrica
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Analysis of the flow field induced by the sessile peritrichous ciliate Opercularia asymmetrica

机译：固着性纤毛纤毛不对称小孔眼诱发的流场分析

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The feeding mechanism of the sessile protozoon Opercularia asymmetrica (Oligohymenophorea, Peritrichia) relies on the cilia beat generating a flow field that convectively transports suspended particles and dissolved substances to the oral cavity of the organism. By use of optical micro-flow measurement and theoretical methods the flow environment of two neighbouring peritrichous ciliate cells is studied. Both, yeast cells (Saccharomyces cerevisiae) and artificial flow tracers are used for the visualisation of the flow field. Artificial tracers are rejected by the protozoa and deviate from the fluid path lines, while yeast cells follow the flow almost perfectly. This is shown through a dimensional analysis of the involved hydrodynamic forces on the tracers. The measured flow field exhibits maximum velocities of 25 mu m/s at around 20 mu m distance ahead of an individual ciliate. The flow field extends 200 mu m from the location of the ciliate. A nicking motion of the protozoon is observed and found not to obey any periodic law. Multiples of protozoa exhibit most commonly an alternating cilia beat regime generating a non-stationary flow field. It can be shown through theoretical methods that fluid exchange is enhanced in this alternating regime compared to a flow field generated by a single ciliate. Fluid exchange depends on the distance of the ciliates from each other and on the alteration frequency of the cilia beat. The comparison of an analytical Stokes' flow solution with the observed fluid flow serves to determine the force required to maintain the flow field against viscous dissipation. The force magnitude is in the order of magnitude of 10-100 pN. (c) 2005 Elsevier Ltd. All rights reserved.
机译：无柄原生动物不对称小卵菌（Oligohymenophorea，Peritrichia）的进食机制依靠纤毛节拍产生流场，该流场将对流的悬浮颗粒和溶解物质输送到生物体的口腔。通过使用光学微流量测量和理论方法，研究了两个相邻的周生纤毛纤毛细胞的流动环境。酵母细胞（Saccharomyces cerevisiae）和人工流动示踪剂均用于流场的可视化。人造示踪剂被原生动物排斥，并偏离流体路径线，而酵母细胞则几乎完全跟随流动。这是通过对示踪剂上涉及的水动力进行的尺寸分析来显示的。测得的流场在单个纤毛虫之前约20微米的距离处表现出25微米/秒的最大速度。流场从纤毛虫的位置延伸200微米。观察到原生动物的刻痕运动，发现它不遵守任何周期性规律。原生动物的倍数最通常表现出交替的纤毛搏动状态，从而产生非平稳的流场。通过理论方法可以证明，与单个纤毛虫产生的流场相比，在这种交替状态下流体交换得到了增强。流体交换取决于纤毛彼此之间的距离以及纤毛搏动的改变频率。将斯托克斯分析流解决方案与观察到的流体流进行比较，可以确定维持流场抵抗粘性耗散所需的力。力的大小在10-100 pN的数量级。 （c）2005 Elsevier Ltd.保留所有权利。

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