Concentric zones, cell migration and neuronal circuits in the Drosophila visual center
Concentric zones, cell migration and neuronal circuits in the Drosophila visual center
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DOI：
10.1242/dev.058370
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发表时间：
2011-03-01
期刊：
影响因子：
4.6
通讯作者：
Sato, Makoto
中科院分区：
文献类型：
--
作者：
Hasegawa, Eri;Kitada, Yusuke;Sato, Makoto
果蝇视叶由多种多样的神经元组成，这些神经元形成具有柱状单位的层状神经堆和视网膜的地形投影。果蝇视叶与哺乳动物视觉系统有许多共同的结构特征。然而，很少有人知道的发育机制，产生神经元的多样性和组织电路的主要区域的视叶，髓质。在这里，我们描述了发展中的髓质和报告的新现象，可以加速我们的果蝇视觉系统的理解的关键特征。髓质神经元的身份是预先确定的幼虫髓质原基，这是细分为同心圆区，其特征在于由四个转录因子的表达：漂流，Runt，Homothorax和脑特异性同源框（Bsh）。这些因子的表达模式与神经元产生的顺序相关。一旦确定了同心圆区，髓质神经元的分布就会迅速改变。每种类型的髓质神经元表现出广泛的，但在蛹的发展过程中明确的迁移模式。克隆分析的结果表明，homothorax是需要指定的神经元类型，通过调节各种目标，包括BSH和细胞粘附分子，如N-钙粘蛋白，而漂移调节一个子集的形态特征的漂移阳性神经元。因此，显示同心圆区的基因可能形成遗传层级，以在髓质中建立神经元回路。
The Drosophila optic lobe comprises a wide variety of neurons, which form laminar neuropiles with columnar units and topographic projections from the retina. The Drosophila optic lobe shares many structural characteristics with mammalian visual systems. However, little is known about the developmental mechanisms that produce neuronal diversity and organize the circuits in the primary region of the optic lobe, the medulla. Here, we describe the key features of the developing medulla and report novel phenomena that could accelerate our understanding of the Drosophila visual system. The identities of medulla neurons are pre-determined in the larval medulla primordium, which is subdivided into concentric zones characterized by the expression of four transcription factors: Drifter, Runt, Homothorax and Brain-specific homeobox (Bsh). The expression pattern of these factors correlates with the order of neuron production. Once the concentric zones are specified, the distribution of medulla neurons changes rapidly. Each type of medulla neuron exhibits an extensive but defined pattern of migration during pupal development. The results of clonal analysis suggest homothorax is required to specify the neuronal type by regulating various targets including Bsh and cell-adhesion molecules such as N-cadherin, while drifter regulates a subset of morphological features of Drifter-positive neurons. Thus, genes that show the concentric zones may form a genetic hierarchy to establish neuronal circuits in the medulla.