An attempt to isolate genes which concern with regional differentiation and evolution of the cerebral cortex

哺乳动物的大脑皮层分为运动区、视觉区和听觉战神等几个功能区。每一个区域都具有特定的细胞结构和神经联系。为了在分子水平上研究结构和功能差异，我们试图分离在旧世界猴（Macaca fascicularis）大脑皮层特定区域表达的基因。由于初级运动皮层（Broadmann的4区）和初级视皮层（Broadmann的17区）的细胞结构差异最大，因此对这两个区域进行了检查。从这些区域制备Poly（A）RNA。采用了两种方法1）抑制消减杂交（SSH：Diachenko et al.（1996）PNAS 93：6025-6030）和2）基因表达的系列分析（SAGE：Velculescu et al.（1995）Science 270：484-487）。1）SSH：我们已经成功地进行了几个使用小鼠脑和小鼠腹部肌肉的初步条件实验。分离大脑特异性和肌肉特异性基因是可能的。然而，在特定区域表达的猴子基因并没有被分离出来。2）SAGE：我们已经对来自区域4和17的大约1,500个标签进行了测序。为了获得可靠的数据，我们需要对十倍多的标签进行测序。然而，继续这种方法存在一些技术问题。结论：用上述两种方法分离大脑皮层特定区域表达的基因是不可能的。这两个地区的基因表达模式差异可能太小，无法用上述方法进行分析。可能需要新的方法如差异显示来分离这些基因。

Cerebral cortex of mammals is devided into seraval fuctional areas such as motor, visual, and orditory ares. Each areas are characterized with specific cytoarchtetures and neuroal connections. To investigate the structural and fuctional difference at the molecular level, we attempted to isolate genes which is expressed in a specific area of the cerebral cortex of the old-world monkey, Macaca fascicularis. Two areas, primary motor cortex (area 4 of Broadmann) and primary visual cortex (area 17 of Broadmann) are examined since the difference of the two areas are the biggest as judged by the cytoarchtechture. Poly (A) RNAs are prepared from these areas. Two approach 1) supression subtractive hybridization (SSH : Diachenko et al. (1996) PNAS 93 : 6025-6030)and 2) serial anaylisis of gene expression (SAGE : Velculescu et al. (1995) Science 270 : 484-487) were employed.1) SSH : We have succeded in several preliminary conditioning experiments using mouse brain and mouse skeltal muscle. It was possible to isolate brain-specific and muscle-specific genes. However, monkey genes expressing in a area-specific mannar were not isolated.2) SAGE : We have sequenced about 1,500 tags from area 4 and 17. In order to obtain reliable data, we need to sequence ten times more tags. However, there are some technical problems to continue this methods. Technical improvements are required to continue this approach.Conclusion : It was not possible to isolate genes which are expressed in some specific area of the cerebral cortex using the two methods above. The difference of gene expression pattern between the two regions may be too small to analyze wiith the methods above. New approach such as differential display may be needed to isolate such genes.