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 alpha-subunit of rod-type transducin (Gt(1)alpha) 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 beta-subunit and cone-type cGMP-gated cation channel alpha-subunit in this region. These results suggest that several components in rod/cone photoreceptors compositely contribute to the deep encephalic phototransduction cascade. Copyright 2000 Wiley-Liss, Inc.