Nuclear migration during karyogamy in rice zygotes is mediated by continuous convergence of actin meshwork toward the egg nucleus
Nuclear migration during karyogamy in rice zygotes is mediated by continuous convergence of actin meshwork toward the egg nucleus
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DOI：
10.1007/s10265-016-0892-2
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发表时间：
2017-03
影响因子：
2.8
通讯作者：
Yukinosuke Ohnishi;T. Okamoto
中科院分区：
文献类型：
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作者：
Yukinosuke Ohnishi;T. Okamoto
受精过程包括两个连续的融合过程：胞浆融合和核融合。随着融合细胞中雄核和雌核的迁移和融合，核配生殖完成。在动物中，由中心体组织的微管控制雌性/雄性原核的迁移。与此相反，被子植物融合配子的核迁移是由肌动蛋白丝控制的，但调节肌动蛋白丝依赖的核迁移的机制尚不清楚。在本研究中，我们制备融合水稻（Oryza sativa L.）利用体外受精技术观察配子/受精卵中肌动蛋白丝和精子核的空间和时间运动。我们的结果表明，卵细胞中的肌动蛋白丝形成了围绕细胞核的网状结构。肌动蛋白网络动力学的定量分析表明，肌动蛋白网络收敛到卵核。在与精子细胞融合的卵细胞中，肌动蛋白丝似乎与精子核膜的一部分相互作用。肌动蛋白丝的运动速度与精子核的运动速度呈正相关。这些结果表明，精子核膜和肌动蛋白丝的物理相互作用，在核融合，精子核迁移到卵核通过肌动蛋白网络的收敛。有趣的是，肌动蛋白丝的速度迅速增加配子融合后，并在核融合过程中进一步升高。除了配子核的迁移，肌动蛋白网络的收敛也可能是早期合子发育的关键。
Fertilization is comprised of two sequential fusion processes; plasmogamy and karyogamy. Karyogamy completes with migration and fusion of the male and female nuclei in the fused cell. In animals, microtubules organized by the centrosome control female/male pronuclei migration. In contrast, the nuclear migration in fused gametes of angiosperms is controlled by actin filaments, but the mechanism that regulates actin filament-dependent nuclear migration is not clear. In this study, we prepared fused rice (Oryza sativaL.) gametes/zygotes using in vitro fertilization and observed the spatial and temporal movements of actin filaments and sperm nuclei. Our results show that actin filaments in egg cells form a meshwork structure surrounding the nuclei. Quantitative analysis of the actin meshwork dynamics suggests that actin meshwork converges toward the egg nucleus. In egg cells fused with sperm cells, actin filaments appeared to interact with a portion of the sperm nuclear membrane. The velocity of the actin filaments was positively correlated with the velocity of the sperm nucleus during karyogamy. These results suggest that sperm nuclear membrane and actin filaments physically interact with each other during karyogamy, and that the sperm nucleus migrates toward the egg nucleus through the convergence of the actin meshwork. Interestingly, actin filament velocity increased promptly after gamete fusion and was further elevated during nuclear fusion. In addition to the migration of gamete nuclei, convergence of actin meshwork may also be critical during early zygotic developments.