Ma P M
Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115.
J Comp Neurol. 1994 Mar 22;341(4):567-79. doi: 10.1002/cne.903410411.
The avidin-biotin-complex method is a popular immunocytochemical technique. This method labels consistently a group of neurons in the lobster ventral nerve cord in the absence of primary antibodies. The specific staining is due to a relatively high level of endogenous biotin (or biocytin) in these neurons. These biotin-positive neurons are located in the supraesophageal, thoracic, and abdominal ganglia. Intraaxonal injection of Lucifer yellow followed by Texas red-conjugated streptavidin staining reveals that the neurons are members of the medial giant (MG) and lateral giant (LG) systems, which are important in mediating rapid tail flipping during escape maneuvers. In neuronal somata, staining is restricted to the cytoplasm. Within MG axons, staining appears as punctate, subaxolemmal structures. Preincubating nerve cords in biocytin or direct intraaxonal injection of biocytin enhances staining of these punctate organelles. In LG axons, staining is localized to fragments of braided filamentous structures that also appear to be associated with the axolemma. Preincubation of ventral nerve cords in various concentrations of biocytin results in the appearance of additional groups of stained neurons, suggesting that there are subsets of neurons with specific biocytin-uptake or -retention mechanisms. In the crayfish, biotin-positive staining is confined to the MG neurons; the LG neurons are not stained. In the earthworm, no staining is observed in the MG and LG axon escape systems. In the goldfish, no biotin-staining is seen in the Mauthner neurons and their axons. The significance of specific localization of biotin or biocytin to subsets of neurons is unclear. It may reflect the presence of high levels of biocytin moieties on biotin-dependent enzymes. Biotin is an important cofactor in the catalytic functions of several decarboxylases crucial in energy production and lipogenesis. Axons of the giant fiber systems in lobsters and crayfish may have high energy and fatty acid synthesis requirements. Increased levels of biotin accumulation may also be related to other functions of the giant axon systems, such as the formation of electrical synapses among themselves and with phasic motoneurons.
抗生物素蛋白-生物素复合物法是一种常用的免疫细胞化学技术。在没有一抗的情况下，该方法能持续标记龙虾腹神经索中的一组神经元。这种特异性染色是由于这些神经元中内源性生物素（或生物胞素）水平相对较高。这些生物素阳性神经元位于食管上神经节、胸神经节和腹神经节。轴突内注射路西法黄，然后进行 Texas 红偶联抗生物素蛋白染色显示，这些神经元是内侧巨纤维（MG）和外侧巨纤维（LG）系统的成员，它们在逃避行为中介导快速甩尾起着重要作用。在神经元胞体中，染色仅限于细胞质。在 MG 轴突内，染色表现为点状的轴膜下结构。在生物胞素中预孵育神经索或直接轴突内注射生物胞素可增强这些点状细胞器的染色。在 LG 轴突中，染色定位于交织丝状结构的片段，这些结构似乎也与轴膜相关。在不同浓度的生物胞素中预孵育腹神经索会导致出现更多组染色神经元，这表明存在具有特定生物胞素摄取或保留机制的神经元亚群。在小龙虾中，生物素阳性染色仅限于 MG 神经元；LG 神经元未被染色。在蚯蚓中，在 MG 和 LG 轴突逃避系统中未观察到染色。在金鱼中，在莫氏神经元及其轴突中未见生物素染色。生物素或生物胞素在神经元亚群中的特异性定位的意义尚不清楚。它可能反映了生物素依赖性酶上生物胞素部分的高水平存在。生物素是几种在能量产生和脂肪生成中起关键作用的脱羧酶催化功能的重要辅助因子。龙虾和小龙虾的巨纤维系统轴突可能对能量和脂肪酸合成有较高需求。生物素积累水平的增加也可能与巨轴突系统的其他功能有关，例如它们自身之间以及与相位运动神经元之间形成电突触。
