effect of monochromatic light upon the erg circadian-rhythm during ontogeny in crayfish (procambarus-clarkii)

Abstract

1. The aim of this work was to investigate if the asymmetric development of the two sets of visual photoreceptors responsible for short wave and long wave sensitivity during crayfish ontogeny influences the characteristics of the electroretinogram (ERG) amplitude rhythm. 2. The parameters of the ERG rhythm of juvenile (2-12 weeks) and adult stages were studied in free-running conditions under blue, red or white light flash test. 3. It was found that monochromatic light produces significant changes in the ERG circadian rhythm parameters in juvenile stages and has a synchronizing effect on the ultradian rhythm prior to the ERG circadian rhythm. 4. Based on these results we propose the existence of two sets of circadian photoreceptors related to two independent systems involved in the synchronization of the ERG circadian rhythm (a short wave and a long wave detection system).