New neurons continue to be produced in the adult brain, especially in the subventricular zone surrounding the lateral ventricles and the dentate gyrus subregion of the hippocampus (Kaplan and Hinds, 1977). The Doublecortin (Dcx) gene is selectively expressed in neuronal precursors and immature neurons (Francis et al., 1999; Gleeson et al., 1999), allowing Dcx gene expression to serve as a marker for the birth of new neurons. In the above image of the dentate gyrus, a brain section from a transgenic mouse expressing Enhanced Green Fluorescent Protein (EGFP) under control of the regulatory elements of Dcx (Gong et al., 2003) was imaged to identify neuronal precursors and immature neurons (green). The fluorescent nucleic acid stain, propidium iodide, provides a marker for all cell types in red. Transgenic mice (Dcx-EGFP) were obtained from the GENSAT project (http://www.gensat.org/).
Francis, F., Koulakoff, A., Boucher, D., Chafey, P., Schaar, B., Vinet, M.C., Friocourt, G., McDonnell, N., Reiner, O., Kahn, A., et al. (1999). Doublecortin is a developmentally regulated, microtubule-associated protein expressed in migrating and differentiating neurons. Neuron 23, 247-256.
Gleeson, J.G., Lin, P.T., Flanagan, L.A., and Walsh, C.A. (1999). Doublecortin is a microtubule-associated protein and is expressed widely by migrating neurons. Neuron 23, 257-271.
Gong, S., Zheng, C., Doughty, M.L., Losos, K., Didkovsky, N., Schambra, U.B., Nowak, N.J., Joyner, A., Leblanc, G., Hatten, M.E., et al. (2003). A gene expression atlas of the central nervous system based on bacterial artificial chromosomes. Nature 425, 917-925.
Kaplan, M.S., and Hinds, J.W. (1977). Neurogenesis in the adult rat: electron microscopic analysis of light radioautographs. Science 197, 1092-1094.