CIRCADIAN REGULATION OF MELATONIN PRODUCTION IN CULTURED ZEBRAFISH PINEAL AND RETINA

Melatonin release was measured from zebrafish pineal organs and retina s maintained in flow-through culture. Pineal organs released melatonin in a strong circadian rhythm through 5 days in constant darkness, and the phase of this rhythm was reset by in vitro exposure to phase-shif ted light cycles. In contrast, the retinal melatonin rhythm rapidly da mped out in constant darkness, even in the presence of (phase-shifted) light cycles. The zebrafish pineal should be useful for in vitro stud ies of vertebrate circadian clock mechanisms.