The pineal gland lies in the brain of vertebrate animals and is involved in detecting light levels in the environment to regulate the circadian rhythm, or daily 'clock', of cyclic activity of an animal. Cells in the pineal contain a protein molecule called pineal opsin (P-opsin), which is related to the photosensitive pigment in the eye, and is activated by light. The P-opsin is believed to be the pigment that initiates light response in the pineal, including suppressing production of the hormone melatonin. This project uses biochemistry on isolated chick pineal cells as a model system to identify other protein molecules called G-proteins, which are activated by light and P-opsin, and which, in turn, regulate melatonin production and entrainment of the pineal circadian clock. Results will help understand how molecular mechanisms in a single cell containing a photosensor, a rhythmic output, and an endogenous clock, can combine to provide an circadian oscillator, and will have an impact on the biology of rhythms as well as on neuroscience and cell biology.
