Phototransduction molecules in the pigeon deep brain

Photoreceptive areas responsible for the regulation of photoperiodicity hav e been localized in the brain of some avian species.We found that immunorea ctivities to rhodopsin and the a-subunit of rod-type transducin (Gt(1)alpha ) were colocalized in cerebrospinal fluid (CSF) contacting neurons in the p igeon lateral septum, a possible site for photoreception. Furthermore, RT-P CR analyses showed specicific gene expression of both cGMP-phosphodiesteras e beta -subunit and conetype cGMP-gated cation channel alpha -subunit in th is region. These results suggest that several components in rod/cone photor eceptors compositely contribute to the deep encephalic phototransduction ca scade. (C) 2000 Wiley-Liss, Inc.