银杏受精过程中颈卵器口形成及精子遗传物质的传递方式

项目名称： 银杏受精过程中颈卵器口形成及精子遗传物质的传递方式

项目编号： No.30800083

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 安丽华

作者单位： 北京大学

项目金额： 20万元

中文摘要： 银杏(Ginkgo biloba L.)是我国特有的中生代孑遗裸子植物，在种子植物的系统演化上具有特殊地位，并且是重要的经济树种。对银杏生殖生物学的研究已有较长历史，但受精过程的一些关键环节，如颈卵器口形成机理及精子遗传物质的传递方式等尚不清楚，而且存在争论。 本研究采用传统光镜和电镜制片技术对银杏颈细胞和液泡状结构的形态结构变化进行观察，在此基础上，采用了新的技术路线和研究手段，如非损伤离子检测术、原位杂交、荧光探针标记、共聚焦激光扫描显微术（CLSM）等对受精前后颈卵器颈细胞及周围区域细胞的钾、钙、镁离子的变化，精细胞和精原细胞发育及受精过程中的遗传物质变化等进行研究，探讨银杏受精过程中颈卵器口的形成机理及精子遗传物质的传递方式。本研究发现颈细胞壁的加厚情况及钾、钙离子的变化与气孔器的保卫细胞类似，推测银杏颈卵器口形成机理与气孔开闭的机理类似。银杏精核在受精前后存在变形和凝集现象，推测其进入颈卵器口可能采取极度变形的策略，类似被子植物中花粉管营养核进入助细胞的方式。本研究试图揭示银杏生殖的一些奥秘，为全面探讨银杏在裸子植物中的系统位置提供依据。

中文关键词： 银杏；颈细胞；液泡状结构；精子；精卵融合

英文摘要： Ginkgo biloba L. is the only extant species of ginkgophyta, retained some curious features in sexual reproduction. Since the discovery of its flagellated spermatozoids, many studies have focused on the reproductive biology of ginkgo. However, some crucial links in fertilization process are uncertain, e.g. how the archegonial neck opening is formed and how the large sperm passes through the much smaller opening of the archegonial neck. The morphology and structure of neck cells and vacuole-like structure were observed by light and electron microscopy. On this basis, some recently developed technologies, including non-invasive micro-test system(NMS), in situ hybridization (FISH), fluorescent probes labelling and confocal laser scanning microscopy（CLSM）were used to detect the fluxes of calcium, potassium and magnesium in neck cells and archegonial chamber before and after fertilization, and the variations of genetic materials in the sperm and spermatogenous cell, in order to determine the dehiscence mode of archegonial neck opening and the manner of the karyogamy in Ginkgo biloba. The results were as following: cell wall thickening among archegonial neck cells and flux changes of calcium and potassium resembled to that guard cells in stoma apparatus, indicated that the formation of archegonial neck opening were probably similar to the open of stomata; the sperm nucleus would change its shape in the process of releasing from pollen tube and condense after entering the egg cell, perhaps it took the strategy of changing neclear shape in passing through the archegonial opening, just like that vegetative nucleus in pollen tube entering the synergid. The present research will benefit to further understanding the evolution of primitive seed plants, be helpful in analyzing the systematic position of ginkgo in gymnosperm.

英文关键词： Ginkgo biloba; archegonial neck cells; vacuole-like structure; sperm; egg-sperm fusion