Lipscomb Brian W, Treloar Helen B, Greer Charles A
Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, PO Box 208082, New Haven, CT 06520-8082, USA.
Cell Tissue Res. 2002 Apr;308(1):7-17. doi: 10.1007/s00441-002-0532-0. Epub 2002 Mar 26.
Cell surface carbohydrates, both in the olfactory system and elsewhere, have been proposed to play critical roles in axon guidance and targeting. Recent studies have used plant lectins to study the heterogeneous distribution of carbohydrates in the olfactory system. One lectin, Dolichos biflorus agglutinin (DBA), heterogeneously labels subsets of glomeruli. In the olfactory epithelium DBA labeled a subset of olfactory sensory neurons (OSNs) including their cilia, dendrites, and somata. OSN axons were also labeled and readily observed in the olfactory nerve and bulb. The patterns of glomerular innervation by DBA labeled (DBA(+)) axons were diverse; some glomeruli contained many labeled axons, while others contained few or no labeled axons. To characterize the heterogeneous innervation of glomeruli, we double labeled olfactory bulbs with DBA and an antibody to olfactory marker protein (OMP). OMP colocalized in most, but not all, DBA(+) axons. To determine if those axons that did not express OMP were immature, we double labeled olfactory bulbs with DBA and anti-GAP-43. GAP-43 rarely colocalized with DBA, suggesting that DBA(+) axons are not, as a population, immature. Triple labeling with all three markers revealed a small subset of DBA(+) axons which did not express either OMP or GAP-43. Electron microscopy established that DBA labels axons in the olfactory nerve and DBA-labeled axons form typical glomerular axodendritic synapses.
在嗅觉系统及其他部位，细胞表面碳水化合物被认为在轴突导向和靶向中发挥关键作用。最近的研究利用植物凝集素来研究碳水化合物在嗅觉系统中的异质性分布。一种凝集素，双花扁豆凝集素（DBA），可异质性标记肾小球的亚群。在嗅觉上皮中，DBA标记了一部分嗅觉感觉神经元（OSN），包括它们的纤毛、树突和胞体。OSN轴突也被标记，并且在嗅神经和嗅球中很容易观察到。DBA标记的（DBA(+)）轴突对肾小球的支配模式多种多样；一些肾小球含有许多标记轴突，而另一些则含有很少或没有标记轴突。为了表征肾小球的异质性支配，我们用DBA和嗅觉标记蛋白（OMP）抗体对嗅球进行双重标记。OMP在大多数但不是所有的DBA(+)轴突中共定位。为了确定那些不表达OMP的轴突是否不成熟，我们用DBA和抗GAP-43对嗅球进行双重标记。GAP-43很少与DBA共定位，这表明作为一个群体，DBA(+)轴突并不不成熟。用所有三种标记进行三重标记揭示了一小部分既不表达OMP也不表达GAP-43的DBA(+)轴突。电子显微镜证实DBA标记嗅神经中的轴突，并且DBA标记的轴突形成典型的肾小球轴树突触。
