Timko M P, Triemer R E, Vasconcelos A C
J Cell Sci. 1981 Dec;52:167-81. doi: 10.1242/jcs.52.1.167.
The freeze-fracture architecture and polypeptide composition of thylakoid membranes of euploid cells of Ricinus communis L. were examined. Electron microscopic examination of the chloroplasts of 1N 2N and 4N cells revealed little variation in the size of chloroplasts, lamellar structure and internal organization of plastids, despite increases in plastid numbers per cell observed to accompany the increase in nuclear ploidy. Thylakoid membranes from euploid cells were also similar in their freeze-fracture morphology. Two basic types of intramembranous particles were observed on the fracture faces of thylakoid membranes of euploid cells. The endoplasmic fracture (EF) face of experimentally unstacked thylakoid membranes of 1N, 2N and 4N cells contain 2 size categories of particles (115-121 A and 164-166 A), whereas the protoplasmic fracture (PF) face of these membranes contain a single size category of particles (85-88 A). The distribution and size of the EF- and PF-face particles were found to be similar among membranes from cells of the 3 ploidy levels. Analysis of the polypeptide composition of thylakoid membranes from 1N, 2N and 4N cells revealed no difference in the relative proportion of the constituent polypeptides of these membranes. The possible factors involved in the regulation of the development of thylakoid structure and composition in the presence of altered nuclear genome size are discussed.
对蓖麻（Ricinus communis L.）整倍体细胞类囊体膜的冷冻断裂结构和多肽组成进行了研究。对1N、2N和4N细胞的叶绿体进行电子显微镜检查发现，尽管观察到每个细胞中质体数量随着核倍性的增加而增加，但叶绿体大小、片层结构和质体内部组织几乎没有变化。整倍体细胞的类囊体膜在冷冻断裂形态上也相似。在整倍体细胞类囊体膜的断裂面上观察到两种基本类型的膜内颗粒。1N、2N和4N细胞经实验解堆叠的类囊体膜的内质断裂（EF）面含有两种大小类别的颗粒（115 - 121 Å和164 - 166 Å），而这些膜的原生质断裂（PF）面含有单一大小类别的颗粒（85 - 88 Å）。发现这3种倍性水平细胞的膜中EF面和PF面颗粒的分布和大小相似。对1N、2N和4N细胞类囊体膜的多肽组成分析表明，这些膜的组成多肽的相对比例没有差异。讨论了在核基因组大小改变的情况下，参与类囊体结构和组成发育调控的可能因素。
