The definition of neuronal type and how it relates to the transcriptome are open questions. Drosophila olfactory projection neurons (PNs) are among the best-characterized neuronal types: different PN classes target dendrites to distinct olfactory glomeruli, while PNs of the same class exhibit indistinguishable anatomical and physiological properties. Using single-cell RNA sequencing, we comprehensively characterized the transcriptomes of most PN classes and unequivocally mapped transcriptomes to specific olfactory function for six classes. Transcriptomes of closely related PN classes exhibit the largest differences during circuit assembly but become indistinguishable in adults, suggesting that neuronal subtype diversity peaks during development. Transcription factors and cell-surface molecules are the most differentially expressed genes between classes and are highly informative in encoding cell identity, enabling us to identify a new lineage-specific transcription factor that instructs PN dendrite targeting. These findings establish that neuronal transcriptomic identity corresponds with anatomical and physiological identity defined by connectivity and function.

中文翻译：

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通过单细胞RNA测序对果蝇嗅觉投射神经元亚型进行分类。

神经元类型的定义及其与转录组的关系尚待解决。果蝇嗅觉投射神经元（PNs）是最典型的神经元类型之一：不同的PN类将树突靶向不同的嗅觉性肾小球，而同一类的PNs则表现出难以区分的解剖和生理特性。使用单细胞RNA测序，我们全面表征了大多数PN类的转录组，并明确地将转录组映射为六类的特定嗅觉功能。紧密相关的PN类的转录组在电路装配过程中表现出最大的差异，但在成年人中变得难以区分，表明神经元亚型多样性在发育过程中达到顶峰。转录因子和细胞表面分子是类别之间表达差异最大的基因，在编码细胞身份方面具有很高的信息意义，使我们能够鉴定出指示PN树突靶向的新谱系特异性转录因子。这些发现建立了神经元转录组身份与由连通性和功能定义的解剖和生理身份相对应。