Ceramides are an important group of sphingolipids that modulate several cellular events. The mechanisms underlying biological actions of ceramides are not fully known, but evidence suggests that ceramides can act through regulation of the biophysical properties of the membrane. However, ceramide-induced changes on membrane properties are complex and depend on several factors. To gain further insight into this subject, we characterized the biophysical impact of very-long acyl chain C24-ceramide in a fluid model membrane under thermodynamic equilibrium and non-equilibrium conditions. Our results show that C24-ceramide readily forms two types of gel domains with distinct properties, likely corresponding to different interdigitated metastable gel phases. Upon reaching thermodynamic equilibrium, only partially interdigitated gel phase coexists with the fluid phase. In addition, C24-ceramide promotes strong changes in the shape of the vesicles, including domains with sharp edges and tubule-like structures. The results suggest that the formation of very long acyl chain ceramides in response to stress stimuli will initially induce a multitude of changes in the organization and fluidity of biological membranes that might be responsible for the activation of different cellular processes.

神经酰胺是一类重要的鞘脂，可调节多种细胞事件。神经酰胺的生物学作用的潜在机制尚不完全清楚，但是证据表明神经酰胺可以通过调节膜的生物物理特性起作用。然而，神经酰胺引起的膜性质变化是复杂的，并且取决于几个因素。为了获得对该主题的进一步了解，我们表征了在热力学平衡和非平衡条件下，流体模型膜中非常长的酰基链C24-神经酰胺的生物物理影响。我们的结果表明，C24-神经酰胺容易形成具有不同特性的两种类型的凝胶域，可能对应于不同的叉指亚稳态凝胶相。达到热力学平衡后，只有部分交叉的凝胶相与液相共存。另外，C24-神经酰胺促进囊泡形状的强烈变化，包括具有尖锐边缘和肾小管样结构的区域。结果表明，响应于应激刺激而形成的很长的酰基链神经酰胺将首先引起生物膜组织和流动性的多种变化，这可能是不同细胞过程的激活所致。