Meeting Abstract

P1.131  Tuesday, Jan. 4  Effect of light on locomotor activity in the marine nudibranch mollusk Tritonia diomedea CLINTON, JM*; HUYNH, M; MURRAY , JA; Washington State U.; Cal State East Bay, Friday Harbor Labs; Cal State East Bay, Friday Harbor Labs mike.k.huynh@gmail.com

Nearly all organisms exhibit endogenous rhythms with a period of roughly 24 hours that have behavioral, neurophysiological and molecular consequences. These circadian rhythms can be entrained by external cues from the environment and are regulated by transcriptional/translation feedback loops of “clock genes” occurring within pacemaker cells. Many exogenous cues are able to modulate these rhythms including light, temperature and food. Rhythms involving locomotion, spawning, and tidal flow have been previously identified in various mollusks. Tritonia diomedea is a subtidal marine nudibranch mollusk which has two functional eyes, each possessing a lens and five photoreceptors, located bilaterally and inferior to each rhinophore. No light-mediated behavior has been published. Our results show a diurnal activity pattern while under a photoperiod of 12 hours of light and 12 hours of darkness, and free-running activity under constant conditions. The environment during the photoperiod was produced using a fluorescent light source and for darkness an LED infrared light source. The responses observed during extracellular recordings performed via the optic nerve confirm the eye’s ability to detect the fluorescent light source but not the infrared. To our knowledge this represents the first description of a behavioral effect in response to light on T. diomedea as well as suggests the presence of a circadian locomotor activity rhythm. Implications for the animal’s behavior in the wild and utility as a model organism for investigating the circadian system are discussed.