Fertilization in Torenia fournieri: Actin organization and nuclear behavior in the central cell and primary endosperm

Studies of the living embryo sacs of Torenia fournieri reveal that the actin cytoskeleton undergoes dramatic changes that correlate with nuclear migration within the central cell and the primary endosperm. Before pollination, actin filaments appear as short bundles randomly distributed in the cortex of the central cell. Two days after anthesis, they become organized into a distinct actin network. At this stage the secondary nucleus, which is located in the central region of the central cell, possesses an associated array of short actin filaments. Soon after pollination, the actin filaments become fragmented in the micropylar end and the secondary nucleus is located next to the egg apparatus. After fertilization, the primary endosperm nucleus moves away from the egg cell and actin filaments reorganize into a prominent network in the cytoplasm of the primary endosperm. Disruption of the actin cytoskeleton with latrunculin A and cytochalasin B indicates that actin is involved in the migration of the nucleus     

Fertilization in Torenia fournieri: Actin organization and nuclear behavior in the central cell and primary endosperm

Studies of the living embryo sacs of Torenia fournieri reveal that the actin cytoskeleton undergoes dramatic changes that correlate with nuclear migration within the central cell and the primary endosperm. Before pollination, actin filaments appear as short bundles randomly distributed in the cortex of the central cell. Two days after anthesis, they become organized into a distinct actin network. At this stage the secondary nucleus, which is located in the central region of the central cell, possesses an associated array of short actin filaments. Soon after pollination, the actin filaments become fragmented in the micropylar end and the secondary nucleus is located next to the egg apparatus. After fertilization, the primary endosperm nucleus moves away from the egg cell and actin filaments reorganize into a prominent network in the cytoplasm of the primary endosperm. Disruption of the actin cytoskeleton with latrunculin A and cytochalasin B indicates that actin is involved in the migration of the nucleus in the central cell. Our data also suggest that the dynamics of actin cytoskeleton may be responsible for the reorganization of the central cell and primary endosperm cytoplasm during fertilization.     

肌动蛋白微丝与生长素浓度梯度分布

生长素参与植物生长发育的各个阶段,如胚胎发生、发育,营养器官发生与形态建成,极性与轴向的建立,维管组织分化,生殖器官的发育等。虽然生长素在植物的各组织器官和细胞中发挥着重要的作用,植物内源生长素的生物合成却是在特异的组织——细胞快速分裂的幼嫩组织中完成的,然后通过韧皮部或受严格控制的细胞—细胞运输系统运送至植物各个部分。生长素的极性运输导致其积累在某些局部组织和细胞内,形成特定梯度分布。生长素对植物生长发育众多方面的调节正是依赖于这一特性。该文综述了近年来有关植物生长发育过程中生长素浓度梯度的形成和相应的生理功能,以及细胞骨架中的微丝参与调控生长素极性运输的研究工作。     

烟草受精前后胚囊中钙调素的免疫细胞化学定位

应用辣根过氧化物酶标记抗体的光镜免疫细胞化学技术和胶体金标记抗体的电镜免疫细胞化学技术定位烟草（Ｎｉｃｏｔｉａｎａｔａｂａｃｕｍｖａｒ．ｍａｃｒｏｐｈｙｌａ）胚囊成员细胞中的钙调素,比较了不同类型细胞之间钙调素的分布特点,并探讨了受精前后钙调素在胚囊中分布的变化规律。     

烟草合子与二胞原胚在离体培养中的发育

用酶解-研磨法分离烟草与大叶烟草受精后的胚囊,继之以显微解剖分离合子与二胞原胚。将3—5个合子或二胞原胚置于微室的琼脂糖小滴中,以预先培养3—4天、分裂1—2次的烟草、大叶烟草或黄花烟草叶肉原生质体饲养。培养基为KM8p与其它附加成分。在25℃与黑暗下静置培养。培养3—4天,约60%合子完成第一次分裂。多数行不等分裂产生大小两个细胞。12天后形成少数原胚或多细胞团。二胞原胚培养亦分裂为多细胞原胚。研究了合子分离方法、合子发育时期、饲养细胞种类与培养天数等因素对合子离体发育的影响。     

烟草未受精中央细胞及其它胚囊细胞的离体分裂

自70年代中期以来,未传粉子房和胚珠的离体培养已在多种植物中取得成功,得到的单倍体植株来源于胶囊中的卵细胞、助细胞以及反足细胞。而分离的未受精胚囊及其成员细胞的离体培养虽屡经尝试,迄今只有Kranz等诱导了玉米未受精卵细胞分裂形成小愈伤组织,至于中央细胞与其它雌配子体细胞则无离体分裂的报道。本文报道大叶烟草未受精中央细胞首次培养成细胞团及其它胚囊细胞启动离体分裂的实验结果。     

烟草中央细胞体内与离体发育中的细胞化学变化

应用金霉素（ＣＴＣ）ｆｌｕｐｈｅｎａｚｉｎｅ（ＦＰＺ）荧光增白剂（ＣＷ）,ＤＡＰＩ等荧光探针,标记由大叶烟草体内直接分离和经过离体培养的中央细胞及卵器细胞,观察膜结合钙及钙调素的分布与细胞僻才细胞核的动态,用碘－碘化钾,苏丹Ⅲ等染色鉴定中央细胞与胚乳细胞内的淀粉与油脂,探讨了中央细胞等在受精前后与培养前后的细胞化学变化。     

蓝猪耳受精过程中中央细胞和初生胚乳细胞中微丝骨架的组装和细胞核的迁移

通过对蓝猪耳(Torenia fournieri)活体胚囊的研究,发现中央细胞和初生胚乳细胞中的微丝骨架在细胞核迁移时发生了显著的变化.授粉前,微丝在中央细胞的周质位置呈现短束状随机分布.开花两天后,它们组装成截然不同的微丝网络,在这个阶段,次生核位于中央细胞中央位置并与短束状的微丝列阵相联系.在授粉发生后不久,分布在珠孔端的微丝发生片断化,此时次生核与卵器相邻.受精后,初生胚乳细胞核从卵细胞处移开, 在初生胚乳细胞中微丝又重组形成清晰的网络结构.用latrunculin A (LAT-A)和细胞松弛素B(cytochalasin B,CB)破坏微丝骨架,得到的试验结果说明,微丝参与了中央细胞中的细胞核迁移运动.数据也表明,在受精过程中,微丝骨架的动力学特性在中央细胞和初生胚乳细胞的胞质重组中起重要作用.