Walsh Kathleen T, Doe Chris Q
Howard Hughes Medical Institute, Institute of Molecular Biology, and Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA.
Howard Hughes Medical Institute, Institute of Molecular Biology, and Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA
Development. 2017 Dec 15;144(24):4552-4562. doi: 10.1242/dev.157826. Epub 2017 Nov 20.
neuroblasts are an excellent model for investigating how neuronal diversity is generated. Most brain neuroblasts generate a series of ganglion mother cells (GMCs) that each make two neurons (type I lineage), but 16 brain neuroblasts generate a series of intermediate neural progenitors (INPs) that each produce 4-6 GMCs and 8-12 neurons (type II lineage). Thus, type II lineages are similar to primate cortical lineages, and may serve as models for understanding cortical expansion. Yet the origin of type II neuroblasts remains mysterious: do they form in the embryo or larva? If they form in the embryo, do their progeny populate the adult central complex, as do the larval type II neuroblast progeny? Here, we present molecular and clonal data showing that all type II neuroblasts form in the embryo, produce INPs and express known temporal transcription factors. Embryonic type II neuroblasts and INPs undergo quiescence, and produce embryonic-born progeny that contribute to the adult central complex. Our results provide a foundation for investigating the development of the central complex, and tools for characterizing early-born neurons in central complex function.
神经母细胞是研究神经元多样性如何产生的优秀模型。大多数脑内神经母细胞会产生一系列神经节母细胞（GMCs），每个神经节母细胞会生成两个神经元（I型谱系），但有16个脑内神经母细胞会产生一系列中间神经祖细胞（INPs），每个中间神经祖细胞会产生4 - 6个神经节母细胞以及8 - 12个神经元（II型谱系）。因此，II型谱系类似于灵长类动物的皮质谱系，可能作为理解皮质扩张的模型。然而，II型神经母细胞的起源仍然是个谜：它们是在胚胎期还是幼虫期形成的？如果它们在胚胎期形成，其后代是否像幼虫期II型神经母细胞的后代那样填充成年中枢复合体？在这里，我们展示了分子和克隆数据，表明所有II型神经母细胞都在胚胎期形成，产生中间神经祖细胞并表达已知的时间转录因子。胚胎期II型神经母细胞和中间神经祖细胞会进入静止状态，并产生对成年中枢复合体有贡献的胚胎期出生的后代。我们的结果为研究中枢复合体的发育提供了基础，也为表征中枢复合体功能中早期出生的神经元提供了工具。
