The light-sensing pigment melanopsin is present in the blind underground mole rat

The blind subterranean mole rat, Spalax, exhibits a higher density of melanopsin-positive retinal ganglion cells compared to the rat.

• Melanopsin is expressed in retinal ganglion cells of the Spalax, which co-store PACAP, a neurotransmitter involved in circadian rhythm regulation.
• Despite severe eye degeneration, Spalax can still adjust its circadian rhythms to environmental light/dark cycles.
• The melanopsin component in Spalax retinal ganglion cells is conserved, suggesting its importance in circadian photoreception.
• The presence of melanopsin indicates a potential role in mediating light signals to the circadian clock in Spalax.

Simplified