Ehara T, Osafune T, Hase E
Department of Microbiology, Tokyo Medical College, Japan.
Exp Cell Res. 1990 Sep;190(1):104-12. doi: 10.1016/0014-4827(90)90150-9.
Cells of Euglena gracilis were synchronized by applying a 14-h light:10-h dark regimen under photoautotrophic conditions and a 10-h light:14-h dark regimen under photoorganotrophic conditions. At a stage just prior to chloroplast division in the cell cycle of these synchronized cultures, chloroplasts temporarily gathered in the posterior part of the cell and were connected to each other by many bridges. Part of the chloroplast aggregate surrounded about half of the nuclear surface, making connections or close contacts at many sites. A chromosome was always attached to the inner membrane of the nuclear envelope at the site of association with the chloroplast. The nucleoids in these aggregate chloroplasts, examined by staining with 4',6-diamidino-2-phenylindole, a DNA fluorochrome, showed profiles of strings or strands with branchings, under photoorganotrophic conditions at least, and some parts of the branchings came close to the site of association with the nucleus. The association between the chloroplast aggregate and the nucleus was also observed in Euglena cells placed in continuous darkness after synchronization under photoorganotrophic conditions, suggesting that these organellar associations are related to the Euglena cell cycle but are not the result of light:dark alternations used for cell synchronization.
在光合自养条件下，通过采用14小时光照：10小时黑暗的培养方案，以及在光有机营养条件下采用10小时光照：14小时黑暗的培养方案，使纤细裸藻细胞同步化。在这些同步培养物的细胞周期中，处于叶绿体分裂前的阶段时，叶绿体暂时聚集在细胞后部，并通过许多桥相互连接。叶绿体聚集体的一部分围绕着大约一半的核表面，在许多位点形成连接或紧密接触。一条染色体总是在与叶绿体结合的位点附着于核膜的内膜。用DNA荧光染料4',6-二脒基-2-苯基吲哚染色检查这些聚集叶绿体中的类核，至少在光有机营养条件下，显示出具有分支的串状或链状轮廓，并且分支的一些部分靠近与细胞核结合的位点。在光有机营养条件下同步化后置于连续黑暗中的裸藻细胞中，也观察到叶绿体聚集体与细胞核之间的关联，这表明这些细胞器的关联与裸藻细胞周期有关，但不是用于细胞同步化的光暗交替的结果。
