Biological Clocks in the Retina: Cellular Mechanisms of Biological Timekeeping

• Published in: International Review of Cytology Vol. 146; pp. 83 - 144
• Main Authors: Block, G.D., Khalsa, S.B.S., McMahon, D.G., Michel, S., Guesz, M.
• Format: Book Chapter Journal Article
• Language: English
• Published: San Diego, CA Elsevier Science & Technology 1993; Academic Press
• Subjects: Animals; Biological and medical sciences; Circadian Rhythm; Electrophysiology; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Neurons - physiology; Photoreceptor Cells - cytology; Photoreceptor Cells - physiology; Retina - cytology; Retina - physiology; Second Messenger Systems; Vertebrates: nervous system and sense organs; Photoreception; Task organization; Discharge pattern; Electrophysiology; Retina; Biological rhythm; Review; Circadian rhythm; Eye; Visual system; Pacemaker; Protein synthesis; Second messenger; Membrane potential; Invertebrata; Mollusca
• ISBN: 9780123645494; 0123645492
• ISSN: 0074-7696; 2163-5854
• DOI: 10.1016/S0074-7696(08)60381-2

This chapter describes and evaluates the progress that has been made in understanding the cellular basis of circadian rhythms. It focuses on experimental results from Aplysia and Bulla retina. The chapter also discusses strategies for studying low-frequency biological rhythms, an elaborate qualitative approach to pacemaker study, and the adequacy of the conceptual framework that guides the cellular circadian research. The eyes of a number of opisthobranchs express circadian rhythms. The circadian pacemaker systems of Bulla and Aplysia are imbedded within gastropod retinas. The Bulla retina consists of a large spheroidal lens surrounded by a layer of photoreceptors and pigmented support cells. In Bulla, each basal retinal neuron (BRN) is a competent circadian pacemaker. Intracellular recording from the large photoreceptors and from BRNs indicate that only they exhibit circadian rhythms in membrane potential, whereas the resting potential of the large photoreceptors remains stable over a 24-hour period. Surgical removal of the photoreceptor layer surrounding the lens does not prevent expression of the circadian rhythm or block the ability of the pacemaker to be phase shifted by light signals.