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首页> 外文期刊>Journal of Molecular Biology >RIGOR AND RELAXED OUTER DYNEIN ARMS IN REPLICAS OF CRYOFIXED MOTILE FLAGELLA
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RIGOR AND RELAXED OUTER DYNEIN ARMS IN REPLICAS OF CRYOFIXED MOTILE FLAGELLA

机译：固定萤火虫鳞茎复制品中的刚性和松弛外肌动力臂。

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A method of image classification based on multivariate statistics has been developed and applied to freeze-etch images of outer dynein arms (ODAs) from cockerel sperm flagella. Demembranated flagella were cryofixed in three different nucleotide states: rigor (i.e. no added ATP); relaxed (i.e. 1 mM ATP plus vanadate); and active (i.e. I mM ATP). Freeze-etch replica fragments from them were coded to conceal their identities and sampled for flagella. From these a total of 6048 individual ODA images were successfully windowed and aligned, covering an angular range of 66 degrees. Each nucleotide condition produced a statistically significant ODA morphology; The relaxed and active morphologies differed only in the angulation of their heads, with the relaxed ODA favouring a more tilted position. The rigor morphology was more distinct and showed a conformational change involving a 12 nm distal shift relative to the A-tubule and highly variable heads and B-links, suggesting an ability to develop tension. Outer arms were classified by discriminant analysis as being either rigor-like, relaxed-like or active-like, and 80% of all ODAs were correctly classified. The misclassification of the remaining 20% indicated morphological heterogeneity in some of the groups. From the rigor group, 8.8% of the ODAs were misclassified as relaxed-like or active-like (i.e. non-rigor-like). It is speculated that this is a consequence of mechanochemical interactions between the B-tubules and the rigor ODAs and/or contaminating ATP remaining after demembranation. Active flagella were found to show ah three morphologies, with 5.4% in the rigor conformation and 18.6% in the relaxed conformation. The finding of rigor-like and relaxed-like ODAs in flagella exposed to ATP is discussed in relation to the cross-bridge cycle. [References: 33]
机译：已经开发了一种基于多元统计数据的图像分类方法，并将其应用于从公鸡精子鞭毛中冻存的外达因臂（ODA）图像。将去膜的鞭毛以三种不同的核苷酸状态冷冻固定：严谨（即不添加ATP）;放松（即1 mM ATP加钒酸盐）;并处于活跃状态（即I mM ATP）。对来自它们的冷冻蚀刻复制品片段进行编码以隐藏其身份，并采样鞭毛。从这些图像中，总共成功地对6048张ODA图像进行了窗口化和对齐，覆盖了66度的角度范围。每种核苷酸条件均产生统计学上显着的ODA形态。放松的和活动的形态仅在其头部的角度上有所不同，放松的ODA支持更倾斜的位置。严格的形态更为明显，并显示出构象变化，相对于A小管以及高度可变的头部和B连接，向远端移动了12 nm，表明具有产生张力的能力。通过判别分析将外臂分类为严谨类，放松类或活跃类，并且所有ODA中的80％已正确分类。其余20％的分类错误表明某些组的形态异质性。在严格的小组中，8.8％的官方发展援助被错误地分类为放松类或主动类（即非严格类）。据推测这是由于B-小管和严格的ODA之间的机械化学相互作用和/或污染了去膜后残留的ATP的结果。发现活性鞭毛显示出三种形态，其中严谨构象为5.4％，松弛构象为18.6％。讨论了与跨桥循环有关的发现，在鞭毛暴露于ATP的过程中，发现了严谨的和类似松弛的ODA。 [参考：33]

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