Neural Pathfinding in an Insect Wing

为了了解神经细胞的轴突如何沿着特定的路径在特定的方向上移动，在简单的系统中检查了轴突生长的底物。轴突的生长可以很容易地在昆虫的翅膀上进行研究，在昆虫翅膀上，神经元在两个单层上皮细胞之间的空间中形成一个简单的二维网络。移植物从上单层移位表明，生长的轴突由其上皮基质中的渐变信号引导向远端至近端方向。用扫描电子显微镜观察了该衬底的整体形貌。轴突在近端生长时，会遇到密度越来越大的基底细胞突起。沿着神经通路的表面分子的分布可以通过这些基本突起的伸展和收缩来调节。轴突生长时在底物表面发现的一种新的蛋白质(2F5)被认为参与了轴突与底物的相互作用。该蛋白已得到纯化，其促进轴突生长的能力将通过原位功能分析和扫描电子显微镜进行研究。此外，一种免疫抑制技术将被用于产生针对其他可能参与轴突路径发现的表面蛋白的抗体。这些研究承诺识别在神经元发育和再生中发挥作用的新分子，不仅在昆虫中，而且在其他物种中也是如此。

To understand how axons of nerve cells navigate in particular directions along defined pathways, the substratum for axonal growth is being examined in the simple system. Growth of axons can easily be studied in an insect wing where neurons form a simple, two- dimensional network nestled in the space between two monolayers of epithelial cells. Transposition of grafts from the upper monolayer suggests that growing axons are guided in a distal to proximal direction by graded cues in their epithelial substratum. Using scanning electron microscopy, the topography of this substratum has been viewed in its entirety. Axons encounter an increasing density of basal cellular processes as they grow proximally. The distribution of surface molecules along the neural pathway can be modulated by extension and retraction of these basal processes. A novel protein (2F5) found on surfaces of the substratum at the time of axonal outgrowth is thought to be involved in the interaction of axons with substrata. This protein has been purified and its ability to promote outgrowth of axons will be studied using functional assays in situ and scanning electron microscopy. In addition, an immunosuppression technique will be used to generate antibodies to other surface proteins that may be involved in axonal pathfinding. These studies promise to identify novel molecules that play a role in neuronal development and regeneration, not only in the insect, but in other species, as well.