Axis establishment and microtubule-mediated waves prior to first cleavage in Beroe ovata.
Axis establishment and microtubule-mediated waves prior to first cleavage in Beroe ovata.
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发表时间：
1993
期刊：
影响因子：
4.6
通讯作者：
Evelyn Houliston;Danièle Carré;Jennifer A. Johnston;Christian Sardet
中科院分区：
文献类型：
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作者：
Evelyn Houliston;Danièle Carré;Jennifer A. Johnston;Christian Sardet
单轴（oral-aboral）和两个对称面的栉水母Beroe ovata成为建立相对于合子核形成的位置和第一次卵裂的方向。在不同的时间剖分的Beroe鸡蛋显示，在鸡蛋组织的差异建立在第一次卵裂前的假定的口-口轴。在第一次有丝分裂之后但不是之前产生的侧向碎片发育成一侧缺乏梳板的幼虫。延时录像显示，波的细胞质重组传播通过层的外围细胞质（外质）的卵在80分钟期间之间的原核融合和第一次卵裂，沿着未来的口背轴。这些波表现为多余精子核周围积累的细胞器斑块的进行性移位和分散，以及一系列表面运动。他们的时间和方向的传播表明，他们可能参与建立细胞质差异相对于胚胎轴。抑制剂实验表明，所观察到的细胞质重组涉及微管。诺考达唑和紫杉醇，防止微管周转，阻止斑块分散和减少表面运动。微生物破坏药物细胞松弛素B不能阻止斑块的消散，但可诱导异常的表面收缩。我们研究了微管组织的变化，使用免疫荧光固定在不同的时间和活卵后注射罗丹明微管蛋白的鸡蛋。在减数分裂结束后，巨大的微管状星状体与每个雄原核相连。原核融合后，它们相继消失，最靠近合子核的先缩小，在单个卵内形成星状体大小的梯度。有丝分裂时间周围的微管行为的区域差异，揭示了由简短的紫杉醇治疗，诱导形成的小微管星状体在该地区的细胞核或纺锤体在第一和第二个细胞周期。因此，观察到的变化波可能反映了当合子核接近有丝分裂时有丝分裂活动的局部出现和扩散。
The single axis (oral-aboral) and two planes of symmetry of the ctenophore Beroe ovata become established with respect to the position of zygote nucleus formation and the orientation of first cleavage. Bisection of Beroe eggs at different times revealed that differences in egg organisation are established in relation to the presumptive oral-aboral axis before first cleavage. Lateral fragments produced after but not before the time of first mitosis developed into larvae lacking comb-plates on one side. Time-lapse video demonstrated that waves of cytoplasmic reorganisation spread through the layer of peripheral cytoplasm (ectoplasm) of the egg during the 80 minute period between pronuclear fusion and first cleavage, along the future oral-aboral axis. These waves are manifest as the progressive displacement and dispersal of plaques of accumulated organelles around supernumerary sperm nuclei, and a series of surface movements. Their timing and direction of propagation suggest they may be involved in establishing cytoplasmic differences with respect to the embryonic axis. Inhibitor experiments suggested that the observed cytoplasmic reorganisation involves microtubules. Nocodazole and taxol, which prevent microtubule turnover,blocked plaque dispersal and reduced surface movements. The microfilament-disrupting drug cytochalasin B did not prevent plaque dispersal but induced abnormal surface contractions. We examined changes in microtubule organisation using immunofluorescence on eggs fixed at different times and in live eggs following injection of rhodamine-tubulin. Giant microtubule asters become associated with each male pronucleus after the end of meiosis. Following pronuclear fusion they disappear successively, those nearest the zygote nucleus shrinking first, to establish gradients of aster size within single eggs. Regional differences in microtubule behaviour around the time of mitosis were revealed by brief taxol treatment, which induced the formation of small microtubule asters in the region of the nucleus or spindle during both first and second cell cycles. The observed wave of change may thus reflect the local appearance and spreading of mitotic activity as the zygote nucleus approaches mitosis.