Parker H. Petit Institute for Bioengineering and Biosciences, School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Nat Commun. 2013;4:1745. doi: 10.1038/ncomms2753.
The telencephalon is the most complex brain region, controlling communication, emotion, movement and memory. Its adult derivatives develop from the dorsal pallium and ventral subpallium. Despite knowledge of genes required in these territories, we do not understand how evolution has shaped telencephalon diversity. Here, using rock- and sand-dwelling cichlid fishes from Lake Malawi, we demonstrate that differences in strength and timing of opposing Hedgehog and Wingless signals establish evolutionary divergence in dorsal-ventral telencephalon patterning. Rock dwellers exhibit early, extensive Hedgehog activity in the ventral forebrain resulting in expression of foxg1 before dorsal Wingless signals, and a larger subpallium. Sand dwellers show rapid deployment of Wingless, later foxg1 expression and a larger pallium. Manipulation of the Hedgehog and Wingless pathways in cichlid and zebrafish embryos is sufficient to mimic differences between rock- versus sand-dweller brains. Our data suggest that competing ventral Hedgehog and dorsal Wingless signals mediate evolutionary diversification of the telencephalon.
端脑是最复杂的脑区，控制着通讯、情绪、运动和记忆。其成年衍生物由背侧皮质和腹侧皮质下区发育而来。尽管我们知道这些区域所需的基因，但我们并不理解进化是如何塑造端脑多样性的。在这里，我们利用来自马拉维湖的岩栖和沙栖慈鲷鱼类，证明了 Hedgehog 和 Wingless 信号的强度和时间的差异，建立了背腹侧端脑模式的进化分歧。岩栖鱼类表现出早期广泛的 Hedgehog 在腹侧前脑的活性，导致 foxg1 在 dorsal Wingless 信号之前表达，并具有更大的皮质下区。沙栖鱼类则表现出 Wingless 的快速激活，随后 foxg1 的表达和更大的大脑皮层。在慈鲷和斑马鱼胚胎中对 Hedgehog 和 Wingless 途径的操作足以模拟岩栖与沙栖鱼类大脑之间的差异。我们的数据表明，竞争的腹侧 Hedgehog 和背侧 Wingless 信号介导了端脑的进化多样化。
