Mitochondrial networks changes over the yeast cell-cycle:The topology, shape and size of mitochondrial networks during the cell cycle in yeast

Mitochondria form tubular networks across a wide range of cell types, from yeast to humans. The mitochondrial network structure is believed to reflect the physiological functions of the organelle. For example, perturbations to the network connectivity can disrupt mitochondrial DNA distribution and integrity or lead to metabolic defects. Therefore, understanding how cells control the shape and topological properties of these networks is of fundamental significance. Previous studies have focused on how these networks scale with cell size and how the interplay between fission-fusion activities gives rise to vastly different network topologies. Surprisingly, despite years of intense work, we still do not have a comprehensive picture of how these networks evolve at the cellular scale over the course of the cell cycle. Here, using extensive 3D imaging and quantitative analysis, we construct the most typical mitochondrial network and its time evolution from birth to division under three different growth conditions (slow, intermediate, and fast growth) in the budding yeast Saccharomyces cerevisiae. In this talk, we will specifically show (i) how yeast mitochondrial networks change during the cell cycle from slow to fast growth conditions, (ii) their dynamics at the shorter (seconds) timescales, and (iii) during the shift from slow to fast growth conditions and vice versa. Together, these results, for the first time, provide a near-complete picture of mitochondrial topological changes at the cellular scale during the cell cycle, opening the way for probing molecular and biophysical mechanisms underlying the control of the network structure.