The Garner lab investigates how bacterial cells grow, examining both extension and division. Both processes require multiple proteins working in parallel, and our research shows that the action of these proteins is carefully regulated to link division and replication. Most of our work occurs in the genetically tractable gram-positive organism Bacillus subtilis which is clearly visible under optical microscopes and can be probed for many cell-biology related questions. Here are B. subtilis cells imaged through a division cycle.

The process of division involves the Z-ring, a complex of proteins that forms at the mid-cell to partition a cell into two cells. Below you can see Z-rings forming and dividing growing B. subtilis cells. 

The organization of the Z-ring is not well understood, and we use biological imaging techniques to examine different proteins in the Z-ring, trying to tease apart the organizational hierarchy. In this 3-dimensional scan of bacillus cell division, the Z-ring is labelled in green and DNA is labelled in red.

Some of this work requires single-molecule tracking to determine the position and motion of individual proteins. Our tracking algorithms allow us to identify single molecules and precisely localize them over a period of time.

For the processes of elongation there is no distinct Z-ring. Instead, complexes of proteins move around the inside of the cell in, maintaining the cell wall by inserting and removing material to allow the cell to grow.

These processes are essential, and when they’re screwed up, cells die in interesting and hilarious ways.