Enhanced circadian photoresponsiveness after prolonged dark adaptation in seven species of diurnal and nocturnal rodents

Refinetti, Roberto

doi:10.1016/j.physbeh.2006.10.004

Cited by 24 publications

(20 citation statements)

References 38 publications

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“…However, it was recently discovered that the photic sensitivity of the degu circadian system dramatically increases during the first month of placement in DD (Refinetti 2007). These data, along with the instability of the phase relationship between the degu circadian pacemaker to its rhythmic output under laboratory conditions (as reviewed above), supports continued use of the Aschoff II method for studies of photic phase-shifts in degus.…”

Section: Fundamental Circadian Parametersmentioning

confidence: 91%

Circadian organization of the diurnal Caviomorph rodent,Octodon degus

Hagenauer

Lee

2008

Biological Rhythm Research

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The Octodon degus, or degu, is an excellent animal model for studying the theoretical and neural underpinnings of diurnality. The power of this model comes from their unique evolutionary lineage, long lives, and relative ease of care in the laboratory for a non-domesticated species. We have summarized the field and laboratory data indicating the critical variables that influence the degus' phase preference and the possible mechanisms for the phase flexibility observed in the field and laboratory. We also review studies examining the physiology and anatomy of light and non-photic inputs to the degu circadian system and studies of the circadian pacemaker itself, with particular emphasis placed on characteristics that appear to be convergent adaptations to a diurnal niche. Finally, we begin to seek the origin for the diurnally-phased activity output of the degu, although we conclude that significant work remains to be done.

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Section: Fundamental Circadian Parametersmentioning

confidence: 91%

Circadian organization of the diurnal Caviomorph rodent,Octodon degus

Hagenauer

Lee

2008

Biological Rhythm Research

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“…Shimomura and Menaker (1994) found no change in the PRC after 7 days in DD but observed a striking amplification of both advances and delays after 7 weeks. Gradual amplification of the PRC is observed in several species upon protracted exposure to DD, however (Refinetti, 2007). Thus, the effect of the tau mutation on PRC amplitude may be to accelerate or exaggerate a process that occurs in wild types.…”

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confidence: 99%

Effects of theDuperMutation on Circadian Responses to Light

et al. 2011

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The circadian mutation duper in Syrian hamsters shortens the free-running circadian period (τDD) by 2 hours when expressed on a tau mutant (τss) background and by 1 hour on a wild-type background. We have examined the effects of this mutation on phase response curves and entrainment. In contrast to wild types, duper hamsters entrained to 14L:10D with a positive phase angle. Super duper hamsters (expressing duper on a τss background) showed weak entrainment, while τss animals either completely failed to entrain or showed sporadic entrainment with episodes of relative coordination. As previously reported, wild-type and τss hamsters show low amplitude resetting in response to 15-minute light pulses after short-term (10 days) exposure to DD. In contrast, super duper hamsters show high amplitude resetting. This effect is attributable to the duper allele, as hamsters carrying duper on a wild-type background also show large phase shifts. Duper mutants that were born and raised in DD also showed high amplitude resetting in response to 15-minute light pulses, indicating that the effect of the mutation on PRC amplitude is not an aftereffect of entrainment to 14L:10D. Hamsters that are heterozygous for duper do not show amplified resetting curves, indicating that for this property, as for determination of free-running period, the mutant allele is recessive. In a modified Aschoff type II protocol, super duper and duper hamsters show large phase shifts as soon as the second day of DD. Despite the amplification of the PRC in super duper hamsters, the induction of Period1 gene expression in the SCN by light is no greater in these mutants than in wild-type animals. Period2 expression in the SCN did not differ between super duper and wild-type hamsters exposed to light at CT15, but albumin site D-binding protein (Dbp) mRNA showed higher basal levels and greater light induction in the SCN of super duper compared to wild-type animals. These results indicate that the duper mutation alters the amplitude of the circadian oscillator and further distinguish it from the tau mutation.

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“…The light:dark cycle is by far the most predictable environmental time cue and acts as a primary synchronizer or zeitgeber of circadian rhythms (Pittendrigh & Minis 1964;Quintero et al 2003;Skene et al 1999). Circadian rhythms are typical of all eukaryotic organisms and are predominantly under endogenous control (Daan & Aschoff 1981;Refinetti 2007). An organism that is devoid of input from external time cues and maintained under constant conditions, will express its own innate circadian rhythm that will free-run with a period (í) of close to 24 h (Aschoff 1981;Szeisler et al 1999;Refinetti 2006).…”

Section: Introductionmentioning

confidence: 99%

Lights Out, Let's Move About: Locomotory Activity Patterns of Wagner's Gerbil from the Desert of Saudi Arabia

et al. 2012

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We investigated the circadian activity rhythm in the little-studied Wagner's gerbil (Gerbillus dasyurus) from the Raydah Protected Area, southwestern Saudi Arabia. In order to assess whether these animals possess an endogenous rhythm of locomotor activity that entrains to the light:dark cycle, they were subjected to three distinct light cycles: an LD cycle (12 h light/12 h dark), a DD cycle (constant darkness) and a DL light cycle (an inverse of the LD light cycle). All eight individuals studied exhibited entrainment of their activity to the light cycles. Under LD, the total percentage of activity during the dark phase was 93.7 ± 1.8%. Activity was distributed throughout the night (mean peak activity 22:46 ± 0:14). All eight animals expressed distinct endogenous free-running rhythms of locomotor activity (mean í = 23:55 ± 0:36). During constant darkness, animals still displayed more activity during the subjective night (75.6 ± 0.4%). Under the DL light cycle, the total percentage of activity was 92.7 ± 1.8% during the dark phase. In conclusion, the daily locomotor activity rhythm of Wagner's gerbil is strongly entrained by the light:dark cycle with the most activity concentrated during the night and consequently this desert-dwelling mammal may thus be considered truly nocturnal.

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Enhanced circadian photoresponsiveness after prolonged dark adaptation in seven species of diurnal and nocturnal rodents

Cited by 24 publications

References 38 publications

Circadian organization of the diurnal Caviomorph rodent,Octodon degus

Circadian organization of the diurnal Caviomorph rodent,Octodon degus

Effects of theDuperMutation on Circadian Responses to Light

Lights Out, Let's Move About: Locomotory Activity Patterns of Wagner's Gerbil from the Desert of Saudi Arabia

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