||Genetic pathways for differentiation of the peripheral nervous system in ascidians.
Waki, Kana ,
Imai, Kaoru SSatou, Yutaka
62015-10-30 , Nature Publishing Group
脊椎動物の感覚神経の進化的起源 -脊椎動物のもつ多様な感覚神経は進化の過程で再獲得された-. 京都大学プレスリリース. 2015-10-30.
Ascidians belong to tunicates, the sister group of vertebrates. Peripheral nervous systems (PNSs) including epidermal sensory neurons (ESNs) in the trunk and dorsal tail regions of ascidian larvae are derived from cells adjacent to the neural plate, as in vertebrates. On the other hand, peripheral ESNs in the ventral tail region are derived from the ventral ectoderm under the control of BMP signalling, reminiscent of sensory neurons of amphioxus and protostomes. In this study, we show that two distinct mechanisms activate a common gene circuit consisting of Msx, Ascl.b, Tox, Delta.b and Pou4 in the dorsal and ventral regions to differentiate ESNs. Our results suggest that ventral ESNs of the ascidian larva are not directly homologous to vertebrate PNSs. The dorsal ESNs might have arisen via co-option of the original PNS gene circuit to the neural plate border in an ancestral chordate.