title: The circadian gene Clock oscillates in the suprachiasmatic nuclei of the diurnal rodent Barbary striped grass mouse, Lemniscomys barbarus: a general feature of diurnality?
abstract: A major challenge in the field of circadian rhythms is to understand the neural mechanisms controlling the oppositely phased temporal organization of physiology and behaviour between night- and day-active animals. Most identified components of the master clock in the suprachiasmatic nuclei (SCN), called circadian genes, display similar oscillations according to the time of day, independent of the temporal niche. This has led to the predominant view that the switch between night- and day-active animals occurs downstream of the master clock, likely also involving differential feedback of behavioral cues onto the SCN. The Barbary striped grass mouse, Lemniscomys barbarus is known as a day-active Muridae. Here we show that this rodent, when housed in constant darkness, displays a temporal rhythmicity of metabolism matching its diurnal behaviour (i.e., high levels of plasma leptin and hepatic glycogen during subjective midday and dusk, respectively). Regarding clockwork in their SCN, these mice show peaks in the mRNA profiles of the circadian gene Period1 (Per1) and the clock-controlled gene Vasopressin (Avp), which occur during the middle and late subjective day, respectively, in accordance with many observations in both diurnal and nocturnal species. Strikingly, expression of the circadian gene Clock in the SCN of the Barbary striped grass mouse was not constitutive as in nocturnal rodents, but it was rhythmic. As this is also the case for the other diurnal species investigated in the literature (sheep, marmoset, and quail), a hypothesis is that the transcriptional control of Clock within the SCN participates in the mechanisms underlying diurnality and nocturnality.
authors.affiliation: Faculty of Science, Laboratory of Biology and Health, Abdelmalek Essaâdi University, BP2121, Tetouan 93002, Morocco; Regulation of Circadian Clocks Team, Institute for Cellular and Integrative Neurosciences, UPR3212, CNRS and University of Strasbourg, Strasbourg, France.
authors.forename: Ibtissam
authors.initials: I
authors.lastname: Chakir
authors.affiliation: Regulation of Circadian Clocks Team, Institute for Cellular and Integrative Neurosciences, UPR3212, CNRS and University of Strasbourg, Strasbourg, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Dumont
authors.affiliation: Regulation of Circadian Clocks Team, Institute for Cellular and Integrative Neurosciences, UPR3212, CNRS and University of Strasbourg, Strasbourg, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Pévet
authors.affiliation: Faculty of Science, Laboratory of Biology and Health, Abdelmalek Essaâdi University, BP2121, Tetouan 93002, Morocco.
authors.forename: Ali
authors.initials: A
authors.lastname: Ouarour
authors.affiliation: Regulation of Circadian Clocks Team, Institute for Cellular and Integrative Neurosciences, UPR3212, CNRS and University of Strasbourg, Strasbourg, France.
authors.forename: Etienne
authors.initials: E
authors.lastname: Challet
authors.affiliation: Regulation of Circadian Clocks Team, Institute for Cellular and Integrative Neurosciences, UPR3212, CNRS and University of Strasbourg, Strasbourg, France. Electronic address: vuillez@unistra.fr.
authors.forename: Patrick
authors.initials: P
authors.lastname: Vuillez
mesh_terms: D000818:Animals; D056926:CLOCK Proteins / Q000235:genetics*; D002940:Circadian Rhythm / Q000502:physiology*; D006003:Glycogen / Q000378:metabolism; D017403:In Situ Hybridization; D020738:Leptin / Q000097:blood; D051379:Mice; D056950:Period Circadian Proteins / Q000096:biosynthesis / Q000235:genetics; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*; D014667:Vasopressins / Q000096:biosynthesis
chemical_list: D020738:Leptin; C539023:Per1 protein, mouse; D056950:Period Circadian Proteins; D014667:Vasopressins; D006003:Glycogen; D056926:CLOCK Proteins
keywords: Circadian rhythms; Clock gene; Diurnality; Lemniscomys barbarus