Widespread Doublecortin Expression in the Cerebral Cortex of the Octodon degus

Abstract

It has been demonstrated that in adulthood rodents show newly born neurons in the subgranular layer (SGL) of the dentate gyrus (DG), and in the subventricular zone (SVZ). The neurons generated in the SVZ migrate through the rostral migratory stream (RMS) to the olfactory bulb. One of the markers of newly generated neurons is doublecortin (DCX). The degu similarly shows significant numbers of DCX-labeled neurons in the SGL, SVZ, and RMS. Further, most of the nuclei of these DCX-expressing neurons are also labeled by proliferating nuclear antigen (PCNA) and Ki67. Finally, whereas in rats and mice DCX-labeled neurons are predominantly present in the SGL and SVZ, with only a few DCX neurons present in piriform cortex, the degu also shows significant numbers of DCX expressing neurons in areas outside of SVZ, DG, and PC. Many areas of neocortex in degu demonstrate DCX-labeled neurons in layer II, and most of these neurons are found in the limbic cortices. The DCX-labeled cells do not stain with NeuN, indicating they are immature neurons.

Generation of a Dcx‐CreERT2 knock‐in mouse for genetic manipulation of newborn neurons

“…In the coronal sections used for this experiment, YFP labeling could also be seen in the piriform cortex and was prominent in animals harvested at late times after tam injection (Figure 5c,d). Dcx+ neurons in this region have been reported in mammalian species from rodents to primates (Fasemore et al, 2018; Luzzati et al, 2009; Nacher et al, 2001; Pekcec et al, 2006; Shapiro et al, 2007; van Groen et al, 2021), and have been fate‐mapped using a prior Dcx‐CreER line to generate a novel type of cortical complex cell (Benedetti et al, 2020). Co‐immunofluorescence for YFP and native Dcx revealed minimal overlap between the two markers in animals harvested 11–16 days after tam (Figure 5e).…”