Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701, Szeged, Hungary.
Planta. 1979 Jan;145(2):199-203. doi: 10.1007/BF00388718.
Polyribosomes (polysomes), active in an amino acid incorporation system in vitro, were isolated from tobacco leaf protoplasts. A comparison of polysome profiles indicated that the polysome/monosome ratio is greatly decreased in isolated protoplasts as compared to the intact leaf. In isolated protoplasts, a marked accumulation of ribosomal subunits was also found. The division of protoplasts, as investigated in the 8-cell and callus stages, was associated with a(n) (at least) partial regeneration of polysome profiles characteristic for leaves. Plasmolysis of leaves attached to the plant had no great effect on the polysome profile. However, leaf excision per se resulted in a dramatic loss of polysomes, even when the leaf tissue was floated on water. It is concluded that the isolation of the cell from its normal environment, and not the osmotic stress and associated increase in RNase activity, is the most important factor responsible for the loss of polysomes in isolated protoplasts.
多核糖体（polysomes）在体外的氨基酸掺入系统中具有活性，可从烟草叶片原生质体中分离得到。对多核糖体图谱的比较表明，与完整叶片相比，分离的原生质体中的多核糖体/单核糖体比率大大降低。在分离的原生质体中，还发现核糖体亚基明显积累。在 8 细胞和愈伤组织阶段对原生质体的分裂进行的研究表明，与叶片特征的多核糖体图谱的（至少）部分再生有关。附着在植物上的叶片的质壁分离对多核糖体图谱没有很大影响。然而，叶片的切除本身会导致多核糖体的急剧丢失，即使叶片组织漂浮在水面上也是如此。因此，结论是细胞与其正常环境的分离，而不是渗透胁迫和相关的 RNase 活性增加，是导致分离的原生质体中多核糖体丢失的最重要因素。
