www.elsevier.com/locate/brainres Available online at www.sciencedirect.com Research Report The circadian gene Clock oscillates in the suprachiasmatic nuclei of the diurnal rodent Barbary striped grass mouse, Lemniscomys barbarus: A general feature of diurnality? Ibtissam Chakir a,b , Ste ´phanie Dumont b , Paul Pe ´vet b , Ali Ouarour a , Etienne Challet b , Patrick Vuillez b,n Q1 a Faculty of Science, Laboratory of Biology and Health, Abdelmalek Essaâdi University, BP2121, Tetouan 93002, Morocco b Regulation of Circadian Clocks Team, Institute for Cellular and Integrative Neurosciences, UPR3212, CNRS and University of Strasbourg, Strasbourg, France article info Article history: Accepted 28 October 2014 Keywords: Clock gene Circadian rhythms Diurnality Lemniscomys barbarus abstract A major challenge in the field of circadian rhythms is to understand the neural mechan- isms 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 down- stream 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. & 2014 Published by Elsevier B.V. BRES : 43897 Model7 pp: À 128ðcol:fig: : NILÞ 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 http://dx.doi.org/10.1016/j.brainres.2014.10.063 0006-8993/& 2014 Published by Elsevier B.V. n Corresponding author at: Institute for Cellular and Integrative Neurosciences, UPR 3212, CNRS, 5 rue Blaise Pascal, 67084 Strasbourg, France. Fax: þ33 3 88 45 66 54. E-mail address: vuillez@unistra.fr (P. Vuillez). brain research ] ( ]]]] ) ]]] – ]]] Please cite this article as: Chakir, I., et al., The circadian gene Clock oscillates in the suprachiasmatic nuclei of the diurnal rodent Barbary striped grass mouse, Lemniscomys barbarus: A general feature of diurnality?. Brain Research (2014), http://dx.doi. org/10.1016/j.brainres.2014.10.063