Taatjes D J, Roth J, Peumans W, Goldstein I J
Interdepartmental Electron Microscopy, Biocenter, University of Basle, Switzerland.
Histochem J. 1988 Sep;20(9):478-90. doi: 10.1007/BF01002646.
The lectin from the elderberry (Sambucus nigra L.) bark, shown to recognize the sequence neuraminic acid (alpha 2,6) galactose/N-acetylgalactosamine, was applied for detecting binding sites in Lowicryl K4M sections by light and electron microscopy. The lectin was used either directly complexed to colloidal gold or in a two-step cytochemical affinity technique. The lectin-gold complex proved to be superior and thus was extensively tested on rat liver, kidney and hepatoma cells as well as on sheep and bovine submandibular glands. Controls to establish specificity of lectin-gold binding included sugar and glycoprotein inhibition tests and enzymic removal of sialic acid. In agreement with biochemical data demonstrating the potentiating effect of sialic acid on the binding of the lectin to oligosaccharides, enzymic removal of sialic acid from liver sections resulted in abolition of lectin staining. However, in the submandibular glands, neuraminidase pretreatment of the sections had no effect on the subsequent lectin-gold binding. In rat kidney some structures became negative while others retained the lectin-gold staining due to binding to penultimate N-acetylgalactosamine exposed after sialic acid removal. In line with this, spot blot analysis demonstrated that the lectin-gold complex reacted with both fetuin and asialofetuin. Taken together, these results suggest that, for cytochemical staining, the sialic acid and the galactose/N-acetylgalactosamine lectin combining subsites of Sambucus nigra L. lectin are equally reactive with cellular glycoconjugates and that neuraminidase predigestion of tissue sections is of utmost importance to ensure specificity of staining for the sequence neuraminic acid (alpha 2,6) galactose/N-acetylgalactosamine.
接骨木（黑接骨木）树皮中的凝集素，已证明能识别神经氨酸（α2,6）半乳糖/N-乙酰半乳糖胺序列，被用于通过光学显微镜和电子显微镜检测Lowicryl K4M切片中的结合位点。该凝集素既可以直接与胶体金复合使用，也可以用于两步细胞化学亲和技术。凝集素-金复合物被证明更具优势，因此在大鼠肝脏、肾脏和肝癌细胞以及绵羊和牛的下颌下腺上进行了广泛测试。用于确定凝集素-金结合特异性的对照包括糖和糖蛋白抑制试验以及唾液酸的酶促去除。与生化数据一致，这些数据表明唾液酸对凝集素与寡糖结合有增强作用，从肝脏切片中酶促去除唾液酸导致凝集素染色消失。然而，在下颌下腺中，对切片进行神经氨酸酶预处理对随后的凝集素-金结合没有影响。在大鼠肾脏中，一些结构变为阴性，而其他结构由于与去除唾液酸后暴露的倒数第二个N-乙酰半乳糖胺结合而保留凝集素-金染色。与此一致，斑点印迹分析表明凝集素-金复合物与胎球蛋白和去唾液酸胎球蛋白都有反应。综上所述，这些结果表明，对于细胞化学染色，黑接骨木凝集素的唾液酸和半乳糖/N-乙酰半乳糖胺凝集素结合亚位点与细胞糖缀合物的反应性相同，并且组织切片的神经氨酸酶预消化对于确保神经氨酸（α2,6）半乳糖/N-乙酰半乳糖胺序列染色的特异性至关重要。
