Laboratory of Plant Bioengineering, Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, Prospekt Lavrentyeva 10, Novosibirsk, 630090, Russian Federation.
Protoplasma. 2011 Oct;248(4):717-24. doi: 10.1007/s00709-010-0234-5. Epub 2011 Feb 1.
Intercellular chromatin migration (cytomixis) in the pollen mother cells of two tobacco (Nicotiana tabacum L.) lines was analyzed by electron microscopy during the first meiotic prophase. The maximal manifestation of cytomixis was observed in the pachytene. As a rule, several cells connected with one another by cytomictic channels wherein the nuclei migrated were observable at this stage. In the majority of cases, nuclei passed from cell to cell concurrently through several closely located cytomictic channels. Chromatin migrated between cells within the nuclear envelope, and its disintegration was unobservable. The nucleus, after passing through cytomictic channels into another cell, can be divided into individual micronuclei or, in the case of a direct contact with another nucleus, can form a nuclear bridge. It has been demonstrated that the chromatin structure after intracellular migration visually matches the chromatin structure before it passed through the cytomictic channel. No signs of pyknosis were observable in the chromatin of the micronuclei formed after cytomixis, and the synaptonemal complex was distinctly seen. The dynamics of changes in the nucleoli during cytomixis was for the first time monitored on an ultrastructural level. Possible mechanisms determining cytomixis are discussed and the significance of this process in plant development is considered.
利用电子显微镜观察了两种烟草（Nicotiana tabacum L.）品系花粉母细胞减数分裂前期Ⅰ的细胞间染色质迁移（胞质桥）。在粗线期观察到胞质桥的最大表现。通常，在这个阶段可以观察到几个通过胞质桥相连的细胞，核在胞质桥中迁移。在大多数情况下，细胞核通过几个紧密相邻的胞质桥同时从一个细胞转移到另一个细胞。染色质在核膜内的细胞之间迁移，其解体不可见。核穿过胞质桥进入另一个细胞后，可以分为单个微核，或者在与另一个核直接接触的情况下，可以形成核桥。已经证明，胞质桥内迁移后的染色质结构在视觉上与通过胞质桥之前的染色质结构相匹配。在胞质桥形成的微核中，没有观察到染色质的固缩现象，而且可以清楚地看到联会复合体。首次在超微结构水平上监测到了核仁在胞质桥过程中的动态变化。讨论了决定胞质桥的可能机制，并考虑了该过程在植物发育中的意义。
