Organelles grow at random intervals, according to physicists.

 Washington University in St. Louis' Talia Ogliore

Jan 07 2023 

Organelles in eukaryotic cells are thought to develop in sporadic spurts from a finite supply of building components, according to research from Washington University in St. Louis.

The majority of life as we know it, including all animals, plants, and fungus, is made up of eukaryotic cells, which are highly organised entities.

The membrane-bound organelles, such as nuclei, which store genetic material, or mitochondria, which generate chemical energy, are constructed and maintained by these cells themselves. But there is still a lot to learn about how they arrange themselves into these physical spaces.

New research by physicists at Washington University in St. Louis demonstrates that eukaryotic cells are capable of tightly controlling average changes in organelle size. Their new approach shows that organelles expand in random bursts from a finite pool of building blocks by proving that organelle sizes follow a universal scaling relationship that the scientists expect theoretically.

According to Shankar Mukherji, an assistant professor of physics at Arts & Sciences, "in our study, we propose that the procedures by which organelles are grown—far from being an ordered 'brick-by-brick' assembly—occur in random bursts."

On January 6, the work appeared in Physical Review Letters.

Such bursts preserve noise in organelle size within a small window while essentially limiting the precision with which organelle size is regulated, according to Mukherji. A broad biophysical method by which cells may maintain, on average, dependable yet changeable organelle sizes is provided by "burstlike proliferation."

Organelles must be adaptable enough to allow cells to expand or contract in response to their surroundings. However, some restrictions must be kept on the size of organelles. Although several molecular elements that affect organelle sizes have been previously identified by biologists, this work offers fresh insights into the quantitative concepts underpinning organelle size control.

While the team is eager to investigate how these assembly processes are used across other species and cell types, this work used budding yeast as a model organism. According to Mukherji, they intend to investigate what these robustness patterns might teach us about harnessing organelle assembly for bioengineering applications and identifying organelle biogenesis flaws in the context of sickness.

Budding yeast and human iPS cells also exhibit the same pattern of resilience in organelle size, according to Mukherji. The underlying molecular processes causing these bursts are likely organelle- and maybe species-specific but have not yet been completely understood.