Gene expression profiling of the olfactory tissues from sex-separated and sex-combined female and male mice

We sought to investigate the scope of cellular and molecular changes within a mouse's olfactory system as a function of its exposure to odors emitted from members of the opposite sex. To this end, we housed mice either separated from members of the opposite sex (sex-separated) or together with members of the opposite sex (sex-combined) until six months of age and then profiled transcript levels within the main olfactory epithelium (MOE), vomeronasal organ (VNO), and olfactory bulb (OB) of the mice via RNA-seq. For each tissue type, we then analyzed gene expression differences between sex-separated males and sex-separated females (SM v SF), sex-combined males and sex-combined females (CM v CF), sex-separated females and sex-combined females (SF v CF), and sex-separated males and sex-combined males (SM v CM). Within both the MOE and VNO, we observed significantly more numerous gene expression differences between males and females when mice were sex-separated as compared to sex-combined. Chemoreceptors were highly enriched among the genes differentially expressed between males and females in sex-separated conditions, and these expression differences were found to reflect differences in the abundance of the corresponding sensory neurons. For each combination of tissue (MOE, VNO, OB), sex (F, M), and condition (sex-separated [S], sex-combined [C]), we generated three biological replicate samples of RNA, each of which contained equal quantities of RNA from two different mice. This resulted in a total of 36 samples.本研究旨在探究小鼠嗅觉系统的细胞与分子变化特征，及其暴露于异性个体释放的气味时的变化规律。为此，我们将小鼠分为两组：一组与异性个体隔离饲养（sex-separated），另一组与异性个体合笼饲养（sex-combined），饲养至小鼠6月龄；随后通过RNA测序（RNA-seq）对小鼠的主嗅觉上皮（main olfactory epithelium, MOE）、犁鼻器（vomeronasal organ, VNO）及嗅球（olfactory bulb, OB）中的转录本水平进行检测分析。针对每一种组织类型，我们分别分析了以下各组间的基因表达差异：隔离饲养雄鼠与隔离饲养雌鼠（SM v SF）、合笼饲养雄鼠与合笼饲养雌鼠（CM v CF）、隔离饲养雌鼠与合笼饲养雌鼠（SF v CF），以及隔离饲养雄鼠与合笼饲养雄鼠（SM v CM）。在主嗅觉上皮与犁鼻器中，我们观察到：与异性合笼饲养组相比，异性隔离饲养组的雌雄个体间基因表达差异数量显著更多。在异性隔离饲养条件下的雌雄个体差异表达基因中，化学感受器相关基因显著富集；且此类表达差异可反映对应感觉神经元的丰度差异。针对组织（主嗅觉上皮、犁鼻器、嗅球）、性别（雌鼠F、雄鼠M）及饲养条件（异性隔离[S]、异性合笼[C]）的所有组合，我们均设置了3份生物学重复RNA样本，每份样本均取自2只不同小鼠的等量RNA；最终共获得36份样本。