Retinoic acid synthesis in the developing retina.
Retinoic acid synthesis in the developing retina.
复制标题
视网膜发育中的视黄酸合成。
DOI：
10.1007/978-1-4615-2904-0_20
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发表时间：
1993
影响因子：
--
通讯作者：
Dräger,UC
中科院分区：
文献类型：
--
作者：
McCaffery,P;Dräger,UC
脊椎动物大脑中的神经元信息以地形图的形式表示：大脑中存在视觉世界、听觉空间、触觉体表和运动方向的多种地形表示。地图框架中的信息处理是整个脊椎动物甚至低等物种神经系统的普遍特征。进化的主要进步不在于地图的原理，而在于地图的数量和专业化。这些地图是在胚胎大脑中形成的，因为来自一个大脑区域的神经元过程具有精确地搜索它们在下一个区域中的地址的能力。这种神经元特异性的分子基础仍然很大程度上未知。以视觉系统为例，提出了主要的工作假设，假设有两组细胞表面标记，一组在视网膜图的前后轴上分级，另一组在视网膜图的背腹轴上分级，这使得视生长锥能够与目标中的相应标记相匹配（Sperry，1963）。这种分级标记的表达需要先于基因转录的不对称性。这里描述的酶提供了直接进入视网膜神经元规范这一早期步骤的途径，因为它们的产物视黄酸通过核受体调节基因转录（Chambon 等人，1991）。
Neuronal information in the vertebrate brain is represented in the form of topographical maps: there are multiple topographical representations in the brain of the visual world, of auditory space, of the tactile body surface and of movement directions. Information processing in the framework of maps is a general feature of the nervous system throughout vertebrates and even in lower species. The main advance through evolution is not in the principle of mapping, but in the number and specialization of maps. The maps are formed in the embryonic brain due to a capacity of neuronal processes from one brain area to search out precisely their address in the next area. The molecular basis of this neuronal specificity is still largely unknown. The main working hypothesis, formulated for the example of the visual system, postulates two sets of cell-surface markers, one graded in the antero-posterior, the other in the dorso-ventral axis of the retinal maps, which enable optic growth cones to match up with corresponding markers in their targets (Sperry, 1963). The expression of such graded markers needs to be preceded by an asymmetry in gene transcription. The enzymes described here provide a direct access to this early step of neuronal specification in the retina, as their product, retinoic acid, regulates gene transcription through nuclear receptors (Chambon et al., 1991).