Tilney L G, Byers B
J Cell Biol. 1969 Oct;43(1):148-65. doi: 10.1083/jcb.43.1.148.
On the assumption that the double-coiled pattern of microtubules in the axoneme of Echinosphaerium might be due to links of two sizes between adjacent microtubules, we disassembled microtubules with low temperature and then carefully analyzed the patterns of microtubules that formed upon the addition of heat (22 degrees C) or heat and D(2)O. Although most of the initial clusters of microtubules that formed could not be interpreted as part of an axoneme, the spacings between these microtubules were the same as that in the axoneme, 70 and 300 A. By model building we were able to show that all clusters that form, including stages in the formation of the axoneme and its 12-fold symmetry, could be explained by links of two sizes (70 and 300 A) and the substructure of the microtubule. We could demonstrate these links with improved staining methods. We suggest that nonaxonemal assemblies of microtubules may be eliminated by the natural selection of the most energetically stable configuration of microtubules, all others undergoing disassembly under equilibrium conditions. Model building further supports this suggestion since the model axoneme possesses more links per tubule than any other cluster found.
基于海胆球轴丝中微管的双螺旋模式可能是由于相邻微管之间存在两种尺寸的连接这一假设，我们用低温拆解微管，然后仔细分析了在加热（22摄氏度）或加热并添加重水（D₂O）后形成的微管模式。尽管最初形成的大多数微管簇不能被解释为轴丝的一部分，但这些微管之间的间距与轴丝中的间距相同，为70埃和300埃。通过构建模型，我们能够表明所有形成的簇，包括轴丝形成阶段及其12倍对称性，都可以用两种尺寸（70埃和300埃）的连接以及微管的亚结构来解释。我们可以用改进的染色方法证明这些连接。我们认为，微管的非轴丝组装可能会通过自然选择最具能量稳定性的微管构型而被消除，其他所有构型在平衡条件下都会发生拆解。构建模型进一步支持了这一观点，因为模型轴丝中每个微管的连接比其他任何发现的簇都多。
