CIRCADIAN CLOCK FUNCTION IN ISOLATED EYESTALK TISSUE OF CRAYFISH

Electrical mass response of crayfish photoreceptors (electroretinogram ) was recorded continuously for up to seven days in isolated preparati ons that consisted of the retina and lamina ganglionaris. Electroretin ogram amplitude varied in a circadian manner with a nocturnal acrophas e and a period of 22-23 h in preparations kept in darkness. Acclimatiz ation of animals to reversed light/dark cycles resulted in a phase rev ersal of the rhythm in vitro. The per (period) gene of Drosophila has been implicated in the genesis of rhythms in insects and in vertebrate s. Immunocytochemical staining with an antibody against the PER gene p roduct revealed immunoreactivity in the retinal photoreceptors, as wel l as in cell bodies in the lamina ganglionaris. Labelled axons run dis tally towards the photoreceptors and proximally to other areas of the lamina.