Circadian clock genes expression in different regions of suprachiasmatic nuclei of Tuco-Tucos (Ctenomys coludo) captured in summer and winter

Abstract

In this Argentine/Brazil/USA collaboration project, we will expand the chronobiological study of an endemic species of neotropical subterranean rodents, the tuco-tucos (Ctenomys coludo), through the first characterization of the temporal expression of circadian clock genes in the suprachiasmatic nuclei (SCN) and extra-SCN regions in this species. The SCN are the hypothalamic structures responsible for generating circadian rhythms, establishing the physiological and behavioral temporal organization in mammals through the rhythmic and self-regulated expression of clock genes. SCN are also responsible for photoperiod transduction, resulting in the synchronization of seasonal rhythms with the seasons. Experimental evidence indicates that SCN neurons are organized into coupled subpopulations and that different photoperiods cause changes in their internal temporal organization. We intend to carry out this characterization of circadian clock gene expression using an in situ hybridization (ISH) approach, providing spatial and temporal neuroanatomical patterns in parallel. Coronal brain sections will be collected from newly captured animals during winter and summer, synchronized to their natural photoperiod and sacrificed throughout the circadian cycle. Radioactive riboprobes will be used to detect Per1, Per2, Bmal1 and Avp. The tuco-tuco is especially interesting for this study because, despite being underground, it presents seasonal rhythms and evidence of photoperiod processing when exposed to artificial photoperiods in the laboratory, as well as photoperiod-dependent after-effects when captured at different stations. We expect to observe differences in the expression of these genes in specific areas of the SCN between different seasons, as observed in other rodents housed under artificial photoperiods. (AU)