Huang B Q, Pierson E S, Russell S D, Tiezzi A, Cresti M
Department of Botany and Microbiology, University of Oklahoma, Norman 73019-0245.
Zygote. 1993 May;1(2):143-54. doi: 10.1017/s0967199400001404.
The cytoskeletal organisation of the isolated embryo sac and egg cells of Plumbago zeylanica was examined before, during and after pollen tube penetration into the embryo sac to determine the potential involvement of microtubules and actin filaments in fertilisation. Material was singly and triply stained using Hoechst 33258 to localise DNA, fluorescein isothiocyanate (FITC)-labelled anti-alpha-tubulin to detect microtubules and rhodamine-phalloidin to visualise F-actin. Microtubules in the unfertilised egg cell are longitudinally aligned in the micropylar and mid-lateral areas, aggregating into bundles near the filiform apparatus. In the perinuclear cytoplasm of the egg cell, microtubules become more or less randomly aligned. F-actin bundles form a longitudinally aligned mesh in the chalazal cytoplasm of the egg cell. In the central cell, microtubules and F-actin are distributed along transvacuolar strands and are also evident in the perinuclear region and at the periphery of the cell. During pollen tube penetration, sparse microtubule bundles near the pathway of the pollen tube may form an apparent microtubular 'conduit' surrounding the male gametes at the delivery site. Actin aggregates become organised near the pathway of the pollen tube and at the delivery site of the sperm cells. Subsequently, actin aggregates form a 'corona' structure in the intercellular region between the egg and central cell where gametic fusion occurs. The corona may have a role in maintaining the close proximity of the egg and central cell and helping the two sperm cells move and bind to their target cells. The cytoskeleton may also be involved in causing the two nuclei of the egg and central cell to approach one another at the site of gametic fusion and transporting the two sperm nuclei into alignment with their respective female nucleus. The cytoskeleton is reorganised during early embryogenesis.
在花粉管穿透胚囊之前、期间和之后，对蓝花丹离体胚囊和卵细胞的细胞骨架组织进行了检查，以确定微管和肌动蛋白丝在受精过程中可能发挥的作用。材料分别用Hoechst 33258进行单染和三重染色，以定位DNA，用异硫氰酸荧光素（FITC）标记的抗α -微管蛋白检测微管，并用罗丹明 -鬼笔环肽观察F -肌动蛋白。未受精卵细胞中的微管在珠孔和中侧区域纵向排列，在丝状器附近聚集成束。在卵细胞的核周细胞质中，微管或多或少随机排列。F -肌动蛋白束在卵细胞合点端的细胞质中形成纵向排列的网状结构。在中央细胞中，微管和F -肌动蛋白沿着液泡间的丝分布，在核周区域和细胞周边也很明显。在花粉管穿透过程中，花粉管路径附近稀疏的微管束可能在配子输送部位形成围绕雄配子的明显微管“管道”。肌动蛋白聚集体在花粉管路径附近和精细胞的输送部位形成有序排列。随后，肌动蛋白聚集体在卵细胞和中央细胞之间发生配子融合的细胞间区域形成“冠状”结构。冠状结构可能在维持卵细胞和中央细胞的紧密接近以及帮助两个精细胞移动并结合到其靶细胞方面发挥作用。细胞骨架也可能参与使卵细胞和中央细胞的两个细胞核在配子融合部位彼此靠近，并将两个精核运输到与各自雌核对齐的位置。细胞骨架在早期胚胎发育过程中会重新组织。
