6月21日,，Science在線報道了動粒在細(xì)胞有絲分裂運(yùn)動過程中的結(jié)構(gòu)變化的研究進(jìn)展,。
動粒在有絲分裂中調(diào)節(jié)染色體分離。它們被認(rèn)為與微管之間既存在主動地產(chǎn)力的相互作用,，也存在被動地摩擦的界面。而在這種相互作用中,，微管的相對位置一直不清楚,。
通過測量在正進(jìn)行有絲分裂的活細(xì)胞中熒光標(biāo)記的動粒亞基之間平均距離，研究者推斷在中期振蕩過程中單個動粒內(nèi)存在機(jī)械變形,。動粒亞基間距離在動粒朝向細(xì)胞兩極運(yùn)動時較短,，而在背向兩極運(yùn)動時較長。動粒切換到朝向兩極方向移動時,，其亞基間距離突然下降,，并隨著拉力增加而進(jìn)一步減少。這提示,，向極方向移動過程中的主動力量壓縮著動粒,。數(shù)據(jù)還顯示，在動粒內(nèi)部存在一個主動力的產(chǎn)生界面,，和一個距離細(xì)胞兩極至少20 nm,，獨(dú)立的被動摩擦界面?？傊?，這些界面導(dǎo)致動粒亞基之間持續(xù)的接觸和相互作用，這為產(chǎn)生間歇性的主動動力創(chuàng)造了條件,。
動粒在有絲分裂中的運(yùn)動細(xì)節(jié)的進(jìn)一步揭示,，為研究許多有絲分裂異常相關(guān)的重要疾病，如腫瘤,，某些染色體核型異常遺傳病,，提供了重要的參考。
doi:10.1016/j.cell.2011.10.017
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Deformations Within Moving Kinetochores Reveal Different Sites of Active and Passive Force Generation
Sophie Dumont1,*,?, E. D. Salmon2, Timothy J. Mitchison1
Kinetochores mediate chromosome segregation at mitosis. They are thought to contain both active, force-producing and passive, frictional interfaces with microtubules whose relative locations have been unclear. We inferred mechanical deformation within single kinetochores during metaphase oscillations by measuring average separations between fluorescently labeled kinetochore subunits in living cells undergoing mitosis. Intersubunit distances were shorter in kinetochores moving toward poles than those moving away. Intersubunit separation decreased abruptly when kinetochores switched to poleward movement, and decreased further when pulling force increased, suggesting that active force generation during poleward movement compresses kinetochores. The data revealed an active force-generating interface within kinetochores, and a separate passive frictional interface located at least 20 nm away poleward. Together, these interfaces allow persistent attachment with intermittent active force generation.
