Cell Cycle-Specific Disruption of the Preprophase Band of Microtubules in Fern Protonemata: Effects of Displacement of the Endoplasm by Centrifugation
Cell Cycle-Specific Disruption of the Preprophase Band of Microtubules in Fern Protonemata: Effects of Displacement of the Endoplasm by Centrifugation
复制标题
蕨类原丝体中微管前期带的细胞周期特异性破坏：离心内质置换的影响
作者：
T. Murata;M. Wada
在高等植物细胞中，微管（MT）的前期带（PPB）出现在细胞分裂之前的胞质分裂的未来位置，到中期消失。最近的研究表明，通过离心从PPB区域置换内质延迟PPB的消失。为了研究细胞质在PPB细胞周期特异性破坏中的作用，以铁线蕨（Adiantum capilius-veneris L.）离心两次，使得第一次离心将内质从PPB的位点移位，第二次使其返回到其原始位置。内质，包括有丝分裂的各个阶段的细胞核，可以通过第二次离心返回到PPB的原始区域，PPB在离心的细胞中的有丝分裂期间持续存在。当内质与前期核返回到其原来的位置，PPB没有中断。当具有前中期末期核的内质类似地返回时，PPB在离心终止的10分钟内被破坏。在铁线蕨原丝体细胞中，第一次离心后，在移位的核附近经常形成第二个PPB。在细胞中，内质被认为是已返回到其原始位置在前期/前中期过渡，第二个PPB没有消失，即使最初的PPB被破坏的内质。这些结果表明，PPB的细胞周期特异性破坏受到内质中某些因子的调节，这些因子出现在前中期，即PPB在未离心细胞中被破坏的阶段。
The preprophase band (PPB) of microtubules (MTs), which appears at the future site of cytokinesis prior to cell division in higher plant cells, disappears by metaphase. Recent studies have shown that displacement of the endoplasm from the PPB region by centrifugation delays the disappearance of the PPB. To study the role of the endoplasm in the cell cycle-specific disruption of the PPB, the filamentous protonemal cells of the fern Adiantum capilius-veneris L. were centrifuged twice so that the first centrifugation displaced the endoplasm from the site of the PPB and the second returned it to its original location. The endoplasm, including the nucleus of various stages of mitosis, could be returned by the second centrifugation to the original region of the PPB, which persists during mitosis in the centrifuged cells. When endoplasm with a prophase nucleus was returned to its original location, the PPB was not disrupted. When endoplasm with a prometa-phase telophase nucleus was similarly returned, the PPB was disrupted within 10 min of termination of centrifugation. In protonemal cells of Adiantum, a second PPB is often formed near the displaced nucleus after the first centrifugation. In cells in which the endoplasm was considered to have been returned to its original location at the prophase/prometaphase transition, the second PPB did not disappear even though the initial PPB was disrupted by the endoplasm. These results suggest that cell cycle-specific disruption of the PPB is regulated by some factor(s) in the endoplasm, which appears at prometaphase, i.e. the stage at which the PPB is disrupted in non-centrifuged cells.