Ivette Caldelas

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The molecular clockwork in mammals involves various clock genes with specific temporal expression patterns. Synchronization of the master circadian clock located in the suprachiasmatic nucleus (SCN) is accomplished mainly via daily resetting of the phase of the clock by light stimuli. Phase shifting responses to light are correlated with induction of Per1,(More)
The molecular mechanisms of the mammalian circadian clock located in the suprachiasmatic nucleus have been essentially studied in nocturnal species. Currently, it is not clear if the clockwork and the synchronizing mechanisms are similar between diurnal and nocturnal species. Here we investigated in a day-active rodent Arvicanthis ansorgei, some of the(More)
In mammals, the suprachiasmatic nuclei (SCN) are the site of the master circadian pacemaker whose molecular core mechanism is based on interlocking transcriptional/translational feedback loops involving clock genes. Among clock genes, Per1 and Per2 are important for both the maintenance of circadian rhythmicity and entrainment to light cues. Several(More)
Temporal organization of the molecular clockwork and behavioral output were investigated in nocturnal rats housed in constant darkness and synchronized to nonphotic cues (daily normocaloric or hypocaloric feeding and melatonin infusion) or light (light-dark cycle and daily 1-h light exposure). Clock gene (Per1, Per2 and Bmal1) and clock-controlled gene(More)
In the Syrian hamster a serotonergic (5-HTergic) stimulation during daytime acts on the circadian timing system by inducing behavioral phase advances and by decreasing Per1 and Per2 (Period) mRNA levels in the suprachiasmatic nuclei, containing the main circadian clock in mammals. The present study was conducted in Syrian hamsters, housed in constant(More)
1995). The retina is also capable of maintaining self-sustained oscillations in vitro (Tosini and Menaker, 1996). The retinal clock may gate photic inputs and modulate the SCN clock (Yamazaki et al., 2002). Indirect evidence also suggests the existence of a food-entrainable clock outside the SCN (Mistlberger, 1994; Stephan, 2001). The location of this clock(More)
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