The cytoskeleton organizes germ nuclei with divergent fates and asynchronous cycles in a common cytoplasm during oogenesis in the chordate Oikopleura
The cytoskeleton organizes germ nuclei with divergent fates and asynchronous cycles in a common cytoplasm during oogenesis in the chordate Oikopleura
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DOI：
10.1016/j.ydbio.2006.10.022
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发表时间：
2007-02-15
影响因子：
2.7
通讯作者：
Thompson, Eric M.
中科院分区：
文献类型：
--
作者：
Ganot, Philippe;Kallesoe, Torben;Thompson, Eric M.
生殖系孢囊是一种保守的结构，其中启动减数分裂的细胞通过环道相互连接。在许多物种中，包囊期的持续时间有限，但脊索动物Oikopleura在整个前期I作为一个独特的细胞，多囊保持它。我们发现，尽管共享一个共同的细胞质与减数分裂和护士核均匀分布在1：1的比例，进入减数分裂和随后的内循环护士核是异步的。当卵子发生从难以区分的胚核的合胞体状态进展到共同的细胞质被均匀地分配到分辨的成熟卵母细胞中的最终排列时，多核囊细胞骨架元件发挥了核心作用。在偶线期的染色体群形成过程中，核孔复合物聚集并将减数分裂核锚定在与环管相对的多囊F-肌动蛋白网络上，使卵母细胞在propbase I早期极化。肌动蛋白的合成是卵母细胞生长所必需的，但细胞质细胞器进入卵母细胞的运动不需要货物运输沿着秋水仙素敏感的微管。相反，微管维持F-肌动蛋白支架上的护士核，并阻止它们进入生长的卵母细胞。最后，这是可能的，既解耦减数分裂进程的细胞机制，卵母细胞的生长，并提前响应外部线索的卵母细胞生长的时间。(c)2006年爱思唯尔公司All rights reserved.
Germline cysts are conserved structures in which cells initiating meiosis are interconnected by ring canals. In many species, the cyst phase is of limited duration, but the chordate, Oikopleura, maintains it throughout prophase I as a unique cell, the coenocyst. We show that despite sharing one common cytoplasm with meiotic and nurse nuclei evenly distributed in a 1: 1 ratio, both entry into meiosis and subsequent endocycles of nurse nuclei were asynchronous. Coenocyst cytoskeletal elements played central roles as oogenesis progressed from a syncytial state of indistinguishable germ nuclei, to a final arrangement where the common cytoplasm had been equally partitioned into resolved, mature oocytes. During chromosomal bouquet formation in zygotene, nuclear pore complexes clustered and anchored meiotic nuclei to the coenocyst F-actin network opposite ring canals, polarizing oocytes early in propbase I. F-actin synthesis was required for oocyte growth but movement of cytoplasmic organelles into oocytes did not require cargo transport along colchicine-sensitive microtubules. Instead, microtubules maintained nurse nuclei on the F-actin scaffold and prevented their entry into growing oocytes. Finally, it was possible to both decouple meiotic progression from cellular mechanisms governing oocyte growth, and to advance the timing of oocyte growth in response to external cues. (c) 2006 Elsevier Inc. All rights reserved.