Screening of Visual Center Specific Marker Molecules by Monoclonal Antibody Technique

为了阐明视网膜轴突和视觉中心之间的特异性神经元联系的分子背景，我们承诺利用单克隆抗体产生技术来筛选靶向特异性标记分子。一种单抗A5(MAb-A5)，用于对抗机械分离的非洲爪哇蝌蚪顶盖细胞(51-53期)，与顶盖的第8层和第9层(视神经支配部位)以及间脑和中脑的其他次要视觉中枢结合，但不与视网膜、视神经或视束结合。MAb-A5(A5抗原)的表位是一个分子质量约140K的细胞表面蛋白分子。A5抗原最早出现在发育第39期的顶盖，此时视网膜轴突开始侵入顶盖。除了视觉中心，A5抗原还出现在延髓和脊髓中非常有限的区域。当眼睛移植到非洲爪哇胚胎的背部时，移植眼的视网膜轴突优先到达延髓和脊髓的A5抗原阳性区域。这些结果提示，A5抗原可能是视神经靶点的标志分子，在视网膜轴突的选择性引导或捕获中可能起重要作用。

To clarify the molecular background of the specific neuronal connection between retinal axons and visual centers, we undertook to screen target specific maker molecules by the monoclonal antibody producing technique. A monoclonal antibody A5 (MAb-A5) which was prepared against mechanically dissociated tectal cells of Xenopus tadpoles (at stages 51-53) bound to laminas 8 and 9 (the sites of optic nerve innervation) of the tectum and also other minor visual centers in the diencephalon and midbrain, but not to the retina, optic nerve or optic tract. The epitope of the MAb-A5 (A5 antigen) was a cell surface protein molecule approximately 140 K in molecular weight. The A5 antigen appeared in the tectum at first at stage 39 of development when tectal invasion by retinal axons was initiated. Besides the visual centers, the A5 antigen also appeared in very restricted regions in the medulla and spinal cord. When eyes were transplanted on the back of Xenopus embryos, retinal axons from the transplanted eye preferentially arrived at the A5 antigen-positive regions in the medulla and spinal cord. These findings suggest that the A5 antigen may be a marker molecule of optic nerve targets, and may play important roles in the preferential guiding or trapping of ingrowing retinal axons.