The shapes of giant unilamellar vesicles (GUVs) enclosing polymer molecules at relatively high concentration, used as a model cytoplasm, significantly differ from those containing only small molecules. Here, we investigated the effects of the molecular weights and concentrations of polymers such as polyethylene glycol (PEG), bovine serum albumin (BSA), and DNA on the morphology of GUVs deflated by osmotic pressure. Although small PEG (MW < 1000) does not alter the mode of shape transformation even at >10% (w/w), PEG with MW > 6000 induces budding and pearling transformation at above 1% (w/w). Larger PEG frequently induced small buddings and tubulation from the membrane of mother GUVs. A similar trend was observed with BSA, indicating that the effect is irrelevant to the chemical nature of polymers. More surprisingly, long strands of DNA (>10⁵ bp) enclosed in GUVs induced budding transformation at concentrations as low as 0.01–0.1% (w/w). We expect that this molecular size dependency arises mainly from the depletion volume effect. Our results showed that curving, budding, and tubulation of lipid membranes, which are ubiquitous in living cells, can result from simple cell-mimics consisting of the membrane and cytosolic macromolecules, but without specific shape-determining proteins.

中文翻译：

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封装生物聚合物的单层巨型囊泡的变形模式。

封闭的较高浓度聚合物分子的单层囊泡（GUV）的形状（用作模型细胞质）与仅包含小分子的囊泡的形状明显不同。在这里，我们研究了诸如聚乙二醇（PEG），牛血清白蛋白（BSA）和DNA等聚合物的分子量和浓度对渗透压降低的GUV形态的影响。尽管小的PEG（MW <1000）甚至在> 10％（w / w）时也不会改变形状转换的模式，但MW> 6000的PEG会在1％（w / w）以上诱导出芽和珍珠化转化。较大的PEG经常从母体GUV的膜上引起小芽和小管。使用BSA观察到类似的趋势，表明该作用与聚合物的化学性质无关。更令人惊讶的是封闭在GUV中的⁵ bp）可以以低至0.01-0.1％（w / w）的浓度诱导出芽转化。我们期望这种分子大小依赖性主要来自耗尽体积效应。我们的研究结果表明，活细胞中普遍存在的脂质膜的弯曲，萌芽和成管形成可能是由膜和胞质大分子组成的简单细胞模拟物产生的，但没有确定形状的特定蛋白质。