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采用溴尿嘧啶核苷三磷酸(BrUTP)标记技术,对洋葱(Allium cepa L.)根端分生组织细胞核中RP Ⅱ转录位置进行了研究。经BrUTP和抗BrdU抗体标记后,在电镜下观察到染色质区域周边部位存在大量的金颗粒,该区域金颗粒数目占细胞核内非核仁区域金颗粒总数的92.70%,金颗粒密度为75.42个/μm~2,明显高于染色质问区域和染色质区域中央部位的金颗粒数目的百分比(分别为1.93%和5.37%)和金颗粒密度(分别为2.00个/μm~2和5.89个/μm~2),说明在染色质区域周边部位进行着旺盛的RPⅡ转录位置。经α-鹅膏蕈碱(10μg/L,2h)处理后,非核仁区域金颗粒的减少极其显著,其金颗粒密度从44.60个/μm~2降至2.67个/μm~2,进一步确认该区域中的金颗粒代表RPⅡ转录产物。讨论了完整植物细胞核内RPⅡ转录位置的分布。
The RP Ⅱ transcriptional location in the nucleus of the root apical meristem of Allium cepa L. was studied by BrUTP labeling. BrUTP and anti-BrdU antibody labeling showed that a large number of gold particles were observed around the chromatin region under the electron microscope. The number of gold particles in this region accounted for 92.70% of the total number of gold particles in the non-nucleolar region of the nucleus and the density of gold particles was 75.42 / μm 2, which were significantly higher than the percentage of the number of gold particles (1.93% and 5.37%, respectively) and the density of gold particles (2.00 / μm 2 and 5.89 / μm 2, respectively) 2), indicating that there is a strong RPII transcriptional site in the periphery of the chromatin region. The reduction of gold particles in non-nucleolar areas was extremely significant after treatment with α-amanitine (10 μg / L, 2 h), and the density of gold particles decreased from 44.60 / μm 2 to 2.67 / μm 2. Gold particles in the region represent RPII transcripts. The distribution of RP Ⅱ transcriptional positions in intact plant nuclei was discussed.