Chittka A, Volff Jn, Wizenmann A
Junior Research Group, Biozentrum, Am Hubland, 97074 Würzburg, Germany.
BMC Dev Biol. 2009 Apr 27;9:29. doi: 10.1186/1471-213X-9-29.
During the development of the central nervous system (CNS), patterning processes along the dorsoventral (DV) axis of the neural tube generate different neuronal subtypes. As development progresses these neurons are arranged into functional units with varying cytoarchitecture, such as laminae or nuclei for efficient relaying of information. Early in development ventral and dorsal regions are similar in size and structure. Different proliferation rates and cell migration patterns are likely to result in the formation of laminae or nuclei, eventually. However, the underlying molecular mechanisms that establish these different structural arrangements are not well understood.We undertook a differential display polymerase chain reaction (DD-PCR) screen to identify genes with distinct expression patterns between dorsal and ventral regions of the chick midbrain in order to identify genes which regulate the sculpturing of such divergent neuronal organisation. We focused on the DV axis of the early chick midbrain since mesencephalic alar plate and basal plate develop into laminae and nuclei, respectively.
We identified 53 differentially expressed bands in our initial screen. Twenty-six of these could be assigned to specific genes and we could unambiguously show the differential expression of five of the isolated cDNAs in vivo by in situ mRNA expression analysis. Additionally, we verified differential levels of expression of a selected number of genes by using reverse transcriptase (RT) PCR method with gene-specific primers.One of these genes, QR1, has been previously cloned and we present here a detailed study of its early developmental time course and pattern of expression providing some insights into its possible function. Our phylogenetic analysis of QR1 shows that it is the chick orthologue of Sparc-like 1/Hevin/Mast9 gene in mice, rats, dogs and humans, a protein involved in cell adhesion.
This study reveals some possible networks, which might be involved in directing the difference in neuronal specification and cytoarchitecture observed in the brain.
在中枢神经系统（CNS）发育过程中，沿神经管背腹（DV）轴的模式形成过程产生了不同的神经元亚型。随着发育的进行，这些神经元被排列成具有不同细胞结构的功能单元，如层或核，以便有效地传递信息。在发育早期，腹侧和背侧区域在大小和结构上相似。不同的增殖速率和细胞迁移模式最终可能导致层或核的形成。然而，建立这些不同结构排列的潜在分子机制尚不清楚。我们进行了差异显示聚合酶链反应（DD-PCR）筛选，以鉴定鸡中脑背侧和腹侧区域之间具有不同表达模式的基因，从而确定调节这种不同神经元组织形成的基因。我们关注早期鸡中脑的DV轴，因为中脑翼板和基板分别发育成层和核。
在我们的初始筛选中，我们鉴定出53条差异表达条带。其中26条可归为特定基因，并且我们可以通过原位mRNA表达分析明确显示体内分离的5个cDNA的差异表达。此外，我们使用基因特异性引物通过逆转录酶（RT）PCR方法验证了选定数量基因的差异表达水平。这些基因之一，QR1，先前已被克隆，我们在此展示了对其早期发育时间进程和表达模式的详细研究，为其可能的功能提供了一些见解。我们对QR1的系统发育分析表明，它是小鼠、大鼠、狗和人类中Sparc样1/Hevin/Mast9基因的鸡直系同源物，该蛋白参与细胞粘附。
本研究揭示了一些可能的网络，这些网络可能参与指导在大脑中观察到的神经元特化和细胞结构差异。
