Nuclei determine the spatial origin of mitotic waves.

Area of Science:

• Cell Biology
• Developmental Biology
• Biophysics

Background:

• Traveling waves are crucial for coordinating mitosis across cells.
• The spatial origin of these mitotic waves is not well understood.
• Pacemakers, regions with faster oscillations, are known to initiate waves.

Purpose of the Study:

• To identify the spatial origin of mitotic waves.
• To investigate the role of nuclei and system dimensions in pacemaker formation.
• To understand how localized concentrations of cell cycle regulators influence wave dynamics.

Main Methods:

• Experiments using cell-free extracts of Xenopus laevis eggs.
• Computational modeling of diffusively coupled oscillators with nuclear import.
• Analysis of pacemaker location in relation to nuclear positioning and system dimensions.

Main Results:

• Nuclei act as pacemakers by concentrating cell cycle regulators.
• Nuclear positioning dictates pacemaker location in computational models.
• System dimensions influence nuclear positioning and pacemaker location, favoring boundaries in wider systems.

Conclusions:

• Nuclei are key determinants of mitotic wave initiation sites.
• Spatial confinement and system geometry significantly impact wave origin.
• This study elucidates how physical and biochemical factors control emergent wave behavior in biological systems.