Jokura Kei, Inaba Kazuo
Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan.
Cytoskeleton (Hoboken). 2020 Oct;77(10):442-455. doi: 10.1002/cm.21640. Epub 2020 Nov 4.
The apical organ of ctenophores is the center of sensory information that controls locomotion. Previous studies have described several types of cilia in this organ. However, detailed ciliary structures, particularly axonemal structures, have not been extensively investigated. Here, we reported that the apical organ of the ctenophore Bolinopsis mikado contains six types of cilia with different axonemal structures. These include the typical "9 + 2" motile axonemes, with both outer and inner dynein arms, only the inner dynein arm, or no dynein arm; axonemes with electron-dense structures in the A-tubules; "9 + 0" axonemes lacking the central pair of microtubules; and axonemes with compartmenting lamellae. Considering that "9 + 2" axonemal structures with both dynein arms are thought to be ancestral forms of cilia, the apical organ of ctenophores would comprise an elaborate assembly of modified ciliary forms that sense and transmit extracellular stimuli and generate various fluid flows.
栉水母的顶端器官是控制运动的感觉信息中心。以往的研究已经描述了该器官中的几种纤毛类型。然而，纤毛的详细结构，特别是轴丝结构，尚未得到广泛研究。在这里，我们报告说，日本博林氏栉水母的顶端器官包含六种具有不同轴丝结构的纤毛。这些包括典型的“9 + 2”运动轴丝，具有外动力蛋白臂和内动力蛋白臂、只有内动力蛋白臂或没有动力蛋白臂；A微管中有电子致密结构的轴丝；缺少中央微管对的“9 + 0”轴丝；以及具有分隔片层的轴丝。考虑到具有双动力蛋白臂的“9 + 2”轴丝结构被认为是纤毛的原始形式，栉水母的顶端器官将由经过修饰的纤毛形式精心组装而成，这些纤毛能够感知和传递细胞外刺激并产生各种流体流动。
