Canini A, Grilli Caiola M, Ferrucci L
Department of Biology, University Tor Vergata, Rome, Italy.
Cytometry. 1992;13(3):299-306. doi: 10.1002/cyto.990130312.
Heterocysts and vegetative cells of the filamentous nitrogen-fixing Anabaena azollae isolated from the apex to the basal leaf cavities of Azolla filiculoides were examined by epifluorescent microscope after fluorochrome staining. Acridine orange (AO), DAPI, and chromomycin fluorochromes were used in order to evidence total DNA content and respectively, A + T and G + C bases. Measurements of fluorescence intensities were made on photographic prints by the automatic image analysis system Quantimet 970. Heterocysts contained higher amounts of DNA than did vegetative cells, and their content strongly increased in the basal leaf cavities. The heterocyst DAPI brightness was quite uniform, whereas in vegetative cells DAPI brightness increased from the apex to the basal groups. In vegetative cells from the apex to the median group, the percentage of DAPI brightness was 60-85% with respect to AO brightness, whereas in heterocysts of the same groups DAPI brightness was 40-50% with respect to AO brightness. In the basal group, brightness due to DAPI staining was comparable with those of previous group both in heterocysts and in vegetative cells, whereas chromomycin brightness increased strongly in heterocysts. These data show that heterocyst changes its DNA content and composition in the basal leaf cavities, suggesting that its lifetime is not completely over.
从细叶满江红的叶尖到基部叶腔分离出丝状固氮鱼腥藻的异形胞和营养细胞，经荧光染料染色后，用落射荧光显微镜进行观察。使用吖啶橙（AO）、4',6-二脒基-2-苯基吲哚（DAPI）和嗜铬霉素荧光染料来分别显示总DNA含量以及A+T和G+C碱基。通过自动图像分析系统Quantimet 970对照片打印件上的荧光强度进行测量。异形胞所含的DNA量比营养细胞多，且其含量在基部叶腔中大幅增加。异形胞的DAPI亮度相当均匀，而营养细胞中的DAPI亮度从叶尖到基部群体逐渐增加。在从叶尖到中部群体的营养细胞中，DAPI亮度相对于AO亮度的百分比为60 - 85%，而在同一群体的异形胞中，DAPI亮度相对于AO亮度为40 - 50%。在基部群体中，异形胞和营养细胞中DAPI染色产生的亮度与前一组相当，而嗜铬霉素亮度在异形胞中大幅增加。这些数据表明，异形胞在基部叶腔中改变了其DNA含量和组成，这表明其生命周期并未完全结束。
