Men, J. et al. Commun Biol 3, 336 (2020)

Optogenetics allows researchers to use light to manipulate the activity of neurons in light-senstive, opsin-expressing transgenic animals. A blue light-based system has been used in Drosophila to control the heart rates of larvae, early pupae, and adults, but the dark cuticles of late-stage pupae have prevented effective blue light penetration. To reach the hearts of these flies, researchers at Washington University in St. Louis saw red.

The team engineered flies that expressed opsin proteins in their hearts that are responsive to red light, which can penetrate deeper into an organism and through otherwise obstructing opaque tissues. The red-light approach allowed them to manipulate cardiac pacing during all Drosophila developmental stages. Depending on the opsin used, the researchers could excite or inhibit activity, allowing them to model different cardiac conditions such as tachycardia, bradycardia, and cardiac arrest in the flies.