To visualize the fine structure of compacted DNA in Synechococcus elongatus PCC 7942, which appears at a specific time in the regular light/dark cycle prior to cell division, Chrom EM (Ou et al., 2017) with some modifications was applied. After staining DNA with DRAQ5, the cells were fixed and irradiated by red laser in the presence of DAB, and subsequently fixed with OsO4. A system with He-Ne laser (633 nm) was set up for efficient irradiation of the bacterial cells in aqueous solution. The compacted DNA was visualized by TEM, in ultrathin sections as electron dense staining by osmium black.

中文翻译：

---

使用带有 DAB 光氧化和锇黑的 DRAQ5 标记对细长聚球藻 PCC 7942 的压缩 DNA 进行 TEM 观察。

为了可视化细长聚球藻 PCC 7942 中压缩 DNA 的精细结构，该结构出现在细胞分裂之前的常规光/暗循环中的特定时间，应用了 Chrom EM（Ou 等人，2017）并进行了一些修改。用 DRAQ5 染色 DNA 后，将细胞固定并在 DAB 存在下用红色激光照射，然后用 OsO4 固定。建立了一个带有 He-Ne 激光 (633 nm) 的系统，以有效地照射水溶液中的细菌细胞。压实的 DNA 在超薄切片中通过 TEM 可视化，作为锇黑的电子致密染色。