Department of Cell Biology and Ecology, University of Santiago de Compostela, Compostela, Spain.
J Exp Zool B Mol Dev Evol. 2012 Mar;318(2):79-90. doi: 10.1002/jezb.21444.
Pax6 is involved in the control of neuronal specification, migration, and differentiation in the olfactory epithelium and in the generation of different interneuron subtypes in the olfactory bulb. Whether these roles are conserved during evolution is not known. Cartilaginous fish are extremely useful models for assessing the ancestral condition of brain organization because of their phylogenetic position. To shed light on the evolution of development of the olfactory system in vertebrates and on the involvement of Pax6 in this process, we analyzed by in situ hybridization and immunohistochemistry the expression pattern of Pax6 in the developing olfactory system in a basal vertebrate, the lesser spotted dogfish Scyliorhinus canicula. This small shark is becoming an important fish model in studies of vertebrate development. We report Pax6 expression in cells of the olfactory epithelium and olfactory bulb, and present the first evidence in vertebrates of strings of Pax6-expressing cells extending along the developing olfactory nerve. The results indicate the olfactory epithelium as the origin of these cells. These data are compatible with a role for Pax6 in the development of the olfactory epithelium and fibers, and provide a basis for future investigations into the mechanisms that regulate development of the olfactory system throughout evolution.
Pax6 参与了嗅上皮中神经元的特化、迁移和分化的控制，以及嗅球中不同中间神经元亚型的产生。其在进化过程中是否具有保守作用尚不清楚。软骨鱼由于其系统发育地位，是评估大脑组织祖先状态的极其有用的模型。为了阐明脊椎动物嗅觉系统发育的进化以及 Pax6 在这一过程中的作用，我们通过原位杂交和免疫组织化学分析了 Pax6 在基础脊椎动物——斑点狗鲨 Scyliorhinus canicula 发育中的嗅觉系统中的表达模式。这种小鲨鱼正在成为研究脊椎动物发育的重要鱼类模型。我们报告了 Pax6 在嗅上皮和嗅球细胞中的表达，并在脊椎动物中首次提供了沿发育中的嗅神经延伸的 Pax6 表达细胞串的证据。结果表明嗅觉上皮是这些细胞的起源。这些数据与 Pax6 在嗅上皮和纤维发育中的作用一致，并为未来研究整个进化过程中调节嗅觉系统发育的机制提供了基础。
