Slowest possible replicative life at frigid temperatures for yeast

Area of Science:

• Cellular biology
• Biophysics

Background:

• Living systems must maintain a state far from thermal equilibrium.
• Understanding the fundamental limits on biological processes, such as the pace of life, is crucial for comprehending life's fundamental barriers.

Purpose of the Study:

• To investigate the existence of fundamental barriers that prevent life from progressing arbitrarily slowly.
• To determine the factors that quantitatively control the pace of life in budding yeast.

Main Methods:

• Monitoring the life cycle of budding yeast at low temperatures.
• Utilizing mathematical modeling to analyze yeast's slowed-down life processes.

Main Results:

• Reactive Oxygen Species (ROS) and global gene-expression speed quantitatively determine yeast's pace of life.
• Temperature-dependent speed limits, defining shortest and longest possible cell-doubling times, were established.
• Increased ROS concentration elongates the cell-growth (G1-phase) duration, increasing doubling time.
• Gene-expression speed limits the rate of ROS reduction, setting the shortest possible doubling time.
• Cells require below-threshold ROS concentrations for replication; high ROS leads to cell bursting.

Conclusions:

• Yeast's replicative life cannot progress arbitrarily slowly at a given temperature due to fundamental barriers.
• Cells with the lowest Reactive Oxygen Species (ROS) levels replicate most rapidly.
• These findings suggest fundamental barriers may constrain the thermal slowing of life in other organisms.