Really excited to explore in the future what this could mean for cells. ROS are everywhere in cells and known to strongly increase actin polymerization. So this relatively simple mechanism could play an important physiological role. [5/5]

Experiment with both actin and ParM, separately assembling in distinct regions

We also see this effect with a bacterial actin homolog, ParM …which can lead to more fun patterns. [4/5]

Figure that shows that actin networks can be printed with a variety of fluorophores

This happens with all labeled actins we tried, but even with unlabeled actin, if we add free fluorophores to our experiments. [3/5]

Schematic of mechanism that explains how severing via ROS enhances actin polymerization

The mechanism is surprisingly simple: excited fluorophores create ROS, which sever filaments via oxidation, resulting in more filaments. Because actin polymerization is nucleation-limited, more filaments = more polymerization. [2/5]

Actin network in vitro in the shape of a smiley face

Just posted our new preprint on controlling actin polymerization via light / ROS. doi.org/10.1101/2025...

We found that just the light from time-lapse imaging can increase actin polymerization by many fold. But we can also use this to print patterns! [1/5]