水稻受精前后胚囊内钙调素分布的变化:免疫金电镜观察

用胶体金免疫电镜技术观察了水稻(Oryza sativa subsp. japonica)受精前后胚囊内钙调素的分布变化.授粉后,卵细胞、助细胞和中央细胞内的钙调素较授粉前均有所增加.中央细胞内钙调素的增加要比卵细胞中约早2 h,退化助细胞与宿存助细胞之间的钙调素含量无明显差异.授粉到受精期间,钙调素的主要分布形式由分散的单颗粒转变为聚集颗粒,受精完成后再变为分散的单颗粒形式.胚囊壁及珠心细胞的细胞壁和胞间隙中也观察到钙调素的分布和数量变化.初步讨论了胞内和胞外钙调素在水稻受精与合子形成中的作用.

Changes of Calmodulin Distribution in the Embryo Sac of Oryza sativa Before and After Fertilization: an Immunogold Electron Microscope Study

Changes of calmodulin (CaM) distribution in the embryo sac of rice (Oryza sativa subsp.japonica) at various stages before and after fertilization have been investigated by using immunogold electron microscopy. Before pollination, both cytoplasm and vacuoles of the egg cell, synergids and central cell were labeled by gold particles. A small amount of gold particles were localized in then ucleus, endoplasmic reticulum, mitochondria and dictyosomes. From pollination to fertilization, CaM amount increased in these cells, especially rich in the starch of amyloplasts. Increase of gold particles in the central cell began about 2 h earlier than that in the egg cell. There was no distinct difference of CaM amount between the degenerated and the persistent synergids. It is interesting to observe an obvious change of CaM distribution form during pollination and fertilization from scattered single particles to clustered particles, and back again to single particles after the fertilization finished. CaM was also localized extracellularly in the embryo sac wall as well as in the wall and intercellular space of nucellus cells. The extracellular CaM also changes in its amount and form after pollination. These results suggest that CaM, either intra or extra cellular, may play important roles in fertilization and zygote formation.