Danuser Gaudenz

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Danuser
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Gaudenz
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  • Article
    Kinetochore alignment within the metaphase plate is regulated by centromere stiffness and microtubule depolymerases
    (Rockefeller University Press, 2010-03-08) Jaqaman, Khuloud ; King, Emma M. ; Amaro, Ana C. ; Winter, Jennifer R. ; Dorn, Jonas F. ; Elliott, Hunter L. ; Mchedlishvili, Nunu ; McClelland, Sarah E. ; Porter, Iain M. ; Posch, Markus ; Toso, Alberto ; Danuser, Gaudenz ; McAinsh, Andrew D. ; Meraldi, Patrick ; Swedlow, Jason R.
    During mitosis in most eukaryotic cells, chromosomes align and form a metaphase plate halfway between the spindle poles, about which they exhibit oscillatory movement. These movements are accompanied by changes in the distance between sister kinetochores, commonly referred to as breathing. We developed a live cell imaging assay combined with computational image analysis to quantify the properties and dynamics of sister kinetochores in three dimensions. We show that baseline oscillation and breathing speeds in late prometaphase and metaphase are set by microtubule depolymerases, whereas oscillation and breathing periods depend on the stiffness of the mechanical linkage between sisters. Metaphase plates become thinner as cells progress toward anaphase as a result of reduced oscillation speed at a relatively constant oscillation period. The progressive slowdown of oscillation speed and its coupling to plate thickness depend nonlinearly on the stiffness of the mechanical linkage between sisters. We propose that metaphase plate formation and thinning require tight control of the state of the mechanical linkage between sisters mediated by centromeric chromatin and cohesion.
  • Article
    Directly probing the mechanical properties of the spindle and its matrix
    (Rockefeller University Press, 2010-02-22) Gatlin, Jesse C. ; Matov, Alexandre ; Danuser, Gaudenz ; Mitchison, Timothy J. ; Salmon, Edward D.
    Several recent models for spindle length regulation propose an elastic pole to pole spindle matrix that is sufficiently strong to bear or antagonize forces generated by microtubules and microtubule motors. We tested this hypothesis using microneedles to skewer metaphase spindles in Xenopus laevis egg extracts. Microneedle tips inserted into a spindle just outside the metaphase plate resulted in spindle movement along the interpolar axis at a velocity slightly slower than microtubule poleward flux, bringing the nearest pole toward the needle. Spindle velocity decreased near the pole, which often split apart slowly, eventually letting the spindle move completely off the needle. When two needles were inserted on either side of the metaphase plate and rapidly moved apart, there was minimal spindle deformation until they reached the poles. In contrast, needle separation in the equatorial direction rapidly increased spindle width as constant length spindle fibers pulled the poles together. These observations indicate that an isotropic spindle matrix does not make a significant mechanical contribution to metaphase spindle length determination.