Interspecific single-cell transcriptomic analysis reveals differences in signaling pathways governing gonadal primordial germ cells between chicken and zebra finch (Taeniopygia guttata) [chicken scRNA-seq]

Primordial germ cells (PGCs), major cell resource used in the production of germline chimeras in birds, have been used in conservation of avian genetic resources and production of transgenic animals. Numerous bird species have been put on the brink of extinction due to habitat loss and degradation caused by environmental destruction and climate change, but research on PGCs is limited to specific poultry, such as chickens. Although it has recently been expanding to various bird species, it is still difficult to utilize PGCs due to biological differences and difficulties in in vitro long-term culture. Here, we constructed a single-cell landscape of chicken gonadal PGCs with established long-term culture systems of PGCs and compared them with those of the vocal learning wild bird, the zebra finches. Our results identified the interspecific differences in signaling pathways in gonadal PGCs and somatic cells, respectively. In particular, the NODAL and insulin signaling pathways were more active in zebra finch than in chickens, whereas the FGF downstream signaling pathway known to be important for the proliferation of chicken PGCs, was more active in chickens. These differences may contribute to optimizing the in vitro culture conditions of zebra finch PGCs. This study is the first cross-species single-cell transcriptomic analysis targeting birds, and laid an essential groundwork to contribute to the restoration of endangered birds and the production of transgenic birds by securing sufficient PGCs from various bird species in the future. Overall design: Gonadal cells profiling of male and female chickens at single cell level

原始生殖细胞（Primordial Germ Cells，PGCs）是鸟类生殖系嵌合体制备的核心细胞资源，已被应用于鸟类遗传资源保护与转基因动物制备。由于环境破坏与气候变化引发的栖息地丧失与退化，众多鸟类已濒临灭绝，但目前针对PGCs的研究仅局限于鸡等特定家禽物种。尽管近年来研究范畴已拓展至多种鸟类，但受物种间生物学差异以及体外长期培养技术瓶颈的限制，PGCs的应用仍存在诸多困难。本研究依托已建立的PGCs长期培养体系，绘制了鸡性腺PGCs的单细胞转录组图谱，并与具备鸣唱学习能力的野生鸟类——斑胸草雀的性腺PGCs进行了对比分析。研究结果分别揭示了性腺PGCs与体细胞的种间信号通路差异：具体而言，斑胸草雀的NODAL与胰岛素信号通路活性高于家鸡，而此前被证实对家鸡PGCs增殖至关重要的FGF下游信号通路，则在家鸡中活性更强。上述差异可为优化斑胸草雀PGCs的体外培养条件提供理论依据。本研究是全球首个针对鸟类的跨物种单细胞转录组分析，为未来从多种鸟类中获取足量PGCs以推动濒危鸟类种群恢复与转基因鸟类制备奠定了重要基础。实验设计：对雌雄家鸡的性腺细胞开展单细胞转录组分析。