NON-VISUAL PHOTOTRANSDUCTION IN NON-MAMMALIAN VERTEBRATES

VALDEZ DIEGO J; NIETO PAULA S; GARBARINO-PICO EDUARDO; GUIDO MARIO E

ILCiocco, Italia

Congreso; Gordon Research Conferences; 2008

In mammals, photoreceptors (PRs) located in the inner retina convey photic information to the brain regulating diverse non-image forming (NIF) tasks. In non-mammalian vertebrates, the retina, deep brain PRs, and the pineal organ may be photoreceptive. Here we investigated light perception in the absence of functional cone and rod PRs using GUCY1* chickens, birds carrying a mutation that causes blindness at hatch (Fig. 1). They showed light responses in both the pupillary Light reflex (PLR) (Fig. 6-10 ) and the entrainment of feeding rhythms to a 12:12 h light dark (LD) cycle or constant light conditions (Fig. 2, 5) . Light responses persisted even when the extra-retinal photoperception was inhibited (Fig .3), but they were lost after enucleation (Fig. 4). An action spectrum for the consensual PLRs in blind animals demonstrated that this response is driven by a single opsin/vitamin A2-based photopigment with peak sensitivity around 484 nm (Fig. 9-10, see Table 1 for comparison between animal species). Results represent the first characterization of functional PRs in the chicken inner retina participating in the regulation of NIF activities.