However, this association was not sustained by the observations obtained from the other two strains, where BALB/c had the greatest olfactory sensitivity but did not have the highest number of neuroblasts. Interestingly, a prior assessment of olfactory discrimination learning in 13 adult (10–18 weeks old) inbred mouse strains by

Brown and colleagues revealed that the C57BL/6J strain was capable of acquiring odor discrimination faster than most of the other strains including A/J (data available at the Mouse Phenome Database; MPD: 22531, 22532, 22570). Taking these data together, proliferation in RMS does not appear to be a good predictor of net OB neurogenesis, OB structure and function. Here, we considered the RMS as a discrete neurogenic structure and our results demonstrated GSK458 research buy the variable and heritable nature of cell proliferation in the RMS. A major QTL called Rmspq1 is identified on distal chromosome 11 for regulating the numbers of rapidly dividing precursors in the RMS but not in the SGZ. Furthermore, a subset of polymorphic genes underlying the Rmspq1 confidence interval have emerged as strong candidates due to their role in either cell cycle progression see more or involvement in signaling pathways known to regulate neural proliferation. Future analysis of these genes will include measuring the transcript

and protein abundance in RMS cells and correlating their expression profiles Protein kinase N1 with phenotypic data on the numbers of proliferating cells in the RMS, as well as determining the in vitro and in vivo functions of these genes in RMS proliferation. Overall, our study provides

strong evidence for the allelic effects on neural proliferation and a solid framework for further exploration of other genetic loci and gene variants that are part of the complex regulation of adult neurogenesis. Genetic insights gained from these studies may contribute to the future development of neural stem cell therapies used to compensate for the loss of neurons in neurodegenerative diseases and brain injuries (Elder et al., 2006; Maysami et al., 2008). This work was supported by NIH grants R01DA020677 to DG, AG18245 to DG, U01AA014425 to LL, P20 DA021131 to RW, and a grant from the Methodist Chair in Neuroscience to DG. We thank Derek Rains, Gurjit Rai, Meifen Lu, Richard Cushing, Erich Brauer and Alan Weatherford for their invaluable technical assistance. Abbreviations BrdU bromodeoxyuridine CV cresyl violet DG dentate gyrus GF growth fraction LOD likelihood of the odds LRS likelihood ratio statistic NSCs neural stem cells OB olfactory bulb QTL quantitative trait locus RI recombinant inbred RMS rostral migratory stream SGZ subgranular zone SVZ subventricular zone Tc total cell cycle time Ts S-phase time Fig. S1. Comparison of two BrdU-labeled cell counting methods for quantifying proliferative cells in the RMS.