title: Nocturnal to Diurnal Switches with Spontaneous Suppression of Wheel-Running Behavior in a Subterranean Rodent.
abstract: Several rodent species that are diurnal in the field become nocturnal in the lab. It has been suggested that the use of running-wheels in the lab might contribute to this timing switch. This proposition is based on studies that indicate feed-back of vigorous wheel-running on the period and phase of circadian clocks that time daily activity rhythms. Tuco-tucos (Ctenomys aff. knighti) are subterranean rodents that are diurnal in the field but are robustly nocturnal in laboratory, with or without access to running wheels. We assessed their energy metabolism by continuously and simultaneously monitoring rates of oxygen consumption, body temperature, general motor and wheel running activity for several days in the presence and absence of wheels. Surprisingly, some individuals spontaneously suppressed running-wheel activity and switched to diurnality in the respirometry chamber, whereas the remaining animals continued to be nocturnal even after wheel removal. This is the first report of timing switches that occur with spontaneous wheel-running suppression and which are not replicated by removal of the wheel.
authors.affiliation: Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Patricia
authors.initials: P
authors.lastname: Tachinardi
authors.affiliation: Institute of Arctic Biology, University of Alaska, Fairbanks, United States of America.
authors.forename: Øivind
authors.initials: Ø
authors.lastname: Tøien
authors.affiliation: Centro Regional de Investigaciones Científicas y Transferencia Tecnológica (CRILAR), La Rioja, Argentina.
authors.forename: Veronica S
authors.initials: VS
authors.lastname: Valentinuzzi
authors.affiliation: Department of Biological Sciences, University of Alaska, Anchorage, United States of America.
authors.forename: C Loren
authors.initials: CL
authors.lastname: Buck
authors.affiliation: Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Gisele A
authors.initials: GA
authors.lastname: Oda
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D001831:Body Temperature / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology; D010101:Oxygen Consumption; D010805:Physical Conditioning, Animal; D012377:Rodentia / Q000502:physiology*