Wang Jiadao, Cao Shan, Du Chuan, Chen Darong
State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, People's Republic of China,
Protoplasma. 2013 Oct;250(5):1203-12. doi: 10.1007/s00709-013-0502-2. Epub 2013 May 5.
The mechanism of diatom locomotion has been widely researched but still remains a hypothesis. There are several questionable points on the prevailing model proposed by Edgar, and some of the observed phenomena cannot be completely explained by this model. In this paper, we undertook detailed investigations of cell structures, locomotion, secreted mucilage, and bending deformation for a benthic pennate diatom Navicula species. According to these broad evidences, an updated locomotion model is proposed. For Navicula sp., locomotion is realized via two or more pseudopods or stalks protruded out of the frustules. The adhesion can be produced due to the pull-off of one pseudopod or stalk from the substratum through extracellular polymeric substances. And the positive pressure is generated to balance the adhesion because of the push-down of another pseudopod or stalk onto the substratum. Because of the positive pressure, friction is generated, acting as a driving force of locomotion, and the other pseudopod or stalk can detach from the substratum, resulting in the locomotion. Furthermore, this model is validated by the force evaluation and can better explain observed phenomena. This updated model would provide a novel aspect on underwater locomotion strategy, hence can be useful in terms of artificial underwater locomotion devices.
硅藻运动机制已得到广泛研究，但仍只是一种假说。埃德加提出的主流模型存在几个可疑之处，一些观察到的现象无法用该模型完全解释。在本文中，我们对一种底栖羽纹硅藻舟形藻属物种的细胞结构、运动、分泌的黏液和弯曲变形进行了详细研究。基于这些广泛的证据，我们提出了一个更新的运动模型。对于舟形藻属物种，运动是通过从壳套伸出的两个或更多伪足或柄来实现的。由于一个伪足或柄通过细胞外聚合物从基质上拉开，从而产生附着力。由于另一个伪足或柄向下压在基质上，会产生正压力以平衡附着力。由于正压力，会产生摩擦力，作为运动的驱动力，另一个伪足或柄可以从基质上脱离，从而实现运动。此外，该模型通过力评估得到了验证，并且能够更好地解释观察到的现象。这个更新后的模型将为水下运动策略提供一个新的视角，因此在人造水下运动装置方面可能会很有用。
