title: Daily cycle in oxygen consumption by the sea anemone Nematostella vectensis Stephenson.
abstract: In bilaterian animals, the circadian clock is intimately involved in regulating energetic metabolism. Although cnidarians exhibit diel behavioral rhythms including cycles in locomotor activity, tentacle extension and spawning, daily cycles in cnidarian metabolism have not been described. To explore a possible circadian metabolic cycle, we maintained the anemone Nematostella vectensis in a 12 h light/dark cycle, a reversed light cycle, or in constant darkness. Oxygen consumption rates were measured at intervals using an optical oxygen meter. Respiration rates responded to entrainment with higher rates during light periods. During a second experiment with higher temporal resolution, respiration rates peaked late in the light period. The diel pattern could be detected after six days in constant darkness. Together, our results suggest that respiration rates in Nematostella exhibit a daily cycle that may be under circadian control and that the cycle in respiration rate is not driven by the previously described nocturnal increase in locomotor activity in this species.
authors.affiliation: Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA Bermuda Institute of Ocean Sciences, St. George's GE01, Bermuda.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Maas
authors.affiliation: Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA School of Marine Sciences, University of Maine, Orono, ME 04469, USA.
authors.forename: Ian T
authors.initials: IT
authors.lastname: Jones
authors.affiliation: Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA.
authors.forename: Adam M
authors.initials: AM
authors.lastname: Reitzel
authors.affiliation: Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA atarrant@whoi.edu.
authors.forename: Ann M
authors.initials: AM
authors.lastname: Tarrant
keywords: Circadian; Cnidarian; Respirometry