Takamura Katsumi, Minamida Nami, Okabe Saori
Department of Marine Biology and Science, Faculty of Life Science and Biotechnology, Fukuyama University, Gakuen-cho, Fukuyama 729-0292, Japan.
Zoolog Sci. 2010 Feb;27(2):191-203. doi: 10.2108/zsj.27.191.
We examined the distribution patterns and axonal pathways of cholinergic, GABAergic, and dopaminergic neurons in the central nervous system of Ciona intestinalis larvae, based on the expression patterns of two reporter genes (GFP and LacZ) driven by the promoters of several neuron-specific genes (vesicular acetylcholine transporter, glutamic acid decarboxylase, tyrosine 3-hydroxylase and dopa decarboxylase). Putative cholinergic and GABAergic cells were found in the sensory vesicle (SV) and visceral ganglion (VG), while putative dopaminergic cells were found only in the SV. The axons of almost all putative cholinergic and GABAergic cells in the SV extend posteriorly towards the VG and seem to connect with motor neurons. Some cells extend axons to the proximal region of the tail beyond the trunk-tail boundary. As this tail region contains several neurons, these cells may modulate larval behavior through the latter neurons. We also found that some putative cholinergic and GABAergic cells in the dorsal VG form a complex and extend axons anteriorly to the SV, posteriorly to the tail, and possibly ventrally to some motor neurons. Finally, we observed that one pair of the anterior most putative cholinergic cells in the ventral VG extends axons contralaterally to the right and left caudal axon tracts. We discuss the similarity of these cells to the Mauthner cells in vertebrates.
我们基于由几个神经元特异性基因（囊泡乙酰胆碱转运体、谷氨酸脱羧酶、酪氨酸3-羟化酶和多巴脱羧酶）的启动子驱动的两个报告基因（绿色荧光蛋白和LacZ）的表达模式，研究了玻璃海鞘幼虫中枢神经系统中胆碱能、γ-氨基丁酸能和多巴胺能神经元的分布模式及轴突通路。在感觉囊泡（SV）和内脏神经节（VG）中发现了推定的胆碱能和γ-氨基丁酸能细胞，而推定的多巴胺能细胞仅在SV中发现。SV中几乎所有推定的胆碱能和γ-氨基丁酸能细胞的轴突向后延伸至VG，似乎与运动神经元相连。一些细胞将轴突延伸至尾部近端区域，超出躯干-尾部边界。由于该尾部区域包含多个神经元，这些细胞可能通过后者的神经元调节幼虫行为。我们还发现，背侧VG中的一些推定的胆碱能和γ-氨基丁酸能细胞形成一个复合体，其轴突向前延伸至SV，向后延伸至尾部，并且可能向腹侧延伸至一些运动神经元。最后，我们观察到腹侧VG中最靠前的一对推定的胆碱能细胞将轴突向对侧延伸至左右尾轴突束。我们讨论了这些细胞与脊椎动物中毛特纳细胞的相似性。
