Microtubule dependence of chromosome cycles in Xenopus laevis blastomeres under the influence of a DNA synthesis inhibitor, aphidicolin
Microtubule dependence of chromosome cycles in Xenopus laevis blastomeres under the influence of a DNA synthesis inhibitor, aphidicolin
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DOI：
10.1006/dbio.1997.8540
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发表时间：
1997-05-01
影响因子：
2.7
通讯作者：
Masui, Y
中科院分区：
文献类型：
--
作者：
Clute, P;Masui, Y
非洲爪蟾胚胎在中囊胚过渡期（MET）发育细胞周期的纺锤体组装检查点。我们先前使用动物帽状卵裂球的实验表明，检查点受一种依赖于年龄的机制调节，但不依赖于核质（N/C）比（克吕特特和Masui，1995）。在本研究中，纺锤体组装检查点的出现时间在动物帽状卵裂球的N/C比降低与aphidicolin治疗。用阿非迪霉素处理的2细胞期动物帽状卵裂球在第4次卵裂后以剂量依赖性方式裂解得更慢，但卵裂和染色体周期持续到第11次至第13次卵裂，然后停止。与相同年龄的对照卵裂球相比，用阿非迪霉素处理的卵裂球具有降低的DNA含量和N/C比率。然而，无论N/C比如何，诺考达唑敏感的染色体周期与对照卵裂球同时出现，即第5次卵裂后3至5小时。用阿非迪霉素处理囊胚期动物的头所引起的间期阻滞可以用咖啡因处理来逆转。咖啡因诱导的有丝分裂在MET后变得对诺考达唑敏感，但在MET前不敏感。因此，如果有丝分裂是由咖啡因诱导的，那么在没有有丝分裂纺锤体的情况下稳定促成熟因子活性的相同机制也在用aphidicolin处理的卵裂球中的MBT之后起作用。如前所述，这种机制可能涉及MET时母体mRNA的翻译。(C)北京：科学出版社.
The spindle-assembly checkpoint of the cell cycle develops in Xenopus Iaevis embryos at the midblastula transition (MET). Our previous experiments using animal-cap blastomeres indicate that the checkpoint is regulated by a mechanism that depends on age, but not on the nucleocytoplasmic (N/C) ratio (Clute and Masui, 1995). In the present study, the time of appearance of the spindle-assembly checkpoint is examined in animal-cap blastomeres whose N/C ratio is reduced by treatment with aphidicolin. Animal-cap blastomeres treated with aphidicolin from the 2-cell stage cleave more slowly after 4th cleavage, in a dose-dependent manner, but cleavage and chromosome cycles continue up to the 11th to 13th cleavage and then arrest. Blastomeres treated with aphidicolin have a reduced DNA content and N/C ratio compared to control blastomeres of the same age. Nevertheless, nocodazole-sensitive chromosome cycles appear at the same time as in control blastomeres, at 3 to 5 hr after 5th cleavage, regardless of the N/C ratio. The arrest in interphase caused by treating blastula stage animal caps with aphidicolin can be reversed by treatment with caffeine. The caffeine-induced mitosis becomes sensitive to nocodazole after the MET, but not before. Therefore, the same mechanism which stabilizes maturation-promoting factor activity in the absence of a mitotic spindle also operates after the MBT in blastomeres that are treated with aphidicolin, if mitosis is induced by caffeine. This mechanism may involve the translation of a maternal mRNA at the time of the MET, as suggested previously. (C) 1997 Academic Press.