The completion of chromosome alignment on the spindle equator (congression time) was set as T = 0, and the relative times of the onset of chromosome-to-pole movement were determined.
This allows pairs of replication products to be recognized in mitosis for bipolar alignment on the spindle apparatus.
In fission yeast, intrinsic control of the rod-shape cell geometry is thought to impose interphase microtubule (MT) alignment as the determinant for alignment of the duplicated spindle pole bodies and consequently the orientation of the mitotic spindle and cell division axis (Vogel et al., 2007; Daga and Nurse, 2008).
Execution of an oriented cell division requires establishment of an axis of polarity and alignment of the mitotic spindle along this axis.
Instead, different types of stem cells can use different mechanisms for ensuring the proper alignment of the mitotic spindle during cell division.
Proper alignment of the mitotic spindle in brown algae has been shown to be a MT-dependent process [ 27], and we observed that condensed chromatin was displaced in zygotes treated with paclitaxel or oryzalin (data not shown).
Cells were transfected with a GK construct (C, –control: empty transfection vector; D, + control: GKPID from extant Drosophila Dlg) and scored for alignment of the mitotic spindle (red, tubulin, visualized immunocytochemically) relative to the Pins cortical crescent (green, a GFP-tagged Pins-Ecd fusion).
Nek2 kinase activity also modulates chromosome alignment and signaling of the spindle assembly checkpoint by phosphorylating HEC1, a component of the Ndc80 complex [ 18].
A robust mitotic spindle checkpoint potentially allows for repair of chromosomal damage and to effect their proper alignment; whereas inactivation of the spindle checkpoint leads to rapid cell death.
In particular, Nek2 kinase is responsible for phosphorylation of Hec1, a component of the Ndc80 complex, which is required for normal chromosome alignment and signaling of the spindle assembly checkpoint.
