Phototransduction molecules in the pigeon deep brain

Photoreceptive areas responsible for the regulation of photoperiodicity have been localized in the brain of some avian species. We found that immunoreactivities to rhodopsin and the α-subunit of rod-type transducin (Gt₁α) were colocalized in cerebrospinal fluid (CSF) contacting neurons in the pigeon lateral septum, a possible site for photoreception. Furthermore, RT-PCR analyses showed specific gene expression of both cGMP-phosphodiesterase β-subunit and cone-type cGMP-gated cation channel α-subunit in this region. These results suggest that several components in rod/cone photoreceptors compositely contribute to the deep encephalic phototransduction cascade. (C) 2000 Wiley-Liss, Inc.