How snails engineer their slime
How snails engineer their slime
蜗牛如何“设计”它们的黏液
Snails are well-known for their mucus. The slime is highly valued as an anti-inflammatory and anti-aging ingredient in certain skin care products, and snails can secrete different kinds of mucus with properties tailored to specific functions. A team of German scientists has determined a recipe for how snails achieve that so-called tunability: Collagen and calcium work in tandem to achieve the varying mechanical properties, according to a new paper in the journal Science.
蜗牛以其黏液而闻名。这种黏液在某些护肤品中被视为具有抗炎和抗衰老功效的珍贵成分，而且蜗牛能够分泌出针对特定功能、具有不同特性的黏液。根据发表在《科学》杂志上的一篇新论文，德国的一个科学家团队确定了蜗牛实现这种所谓“可调性”的秘诀：胶原蛋白和钙协同作用，从而实现了不同的机械性能。
Snail mucus is mostly water; it’s the mucins (glycoproteins) and complex carbohydrates that give it that slimy, viscous texture. In addition to cosmetics, the mucus holds great potential for drug delivery. In 2020, scientists found that combining snail slime from a common garden snail with gold nanoparticles helped accelerate wound healing and exhibited anti-inflammatory properties in mice.
蜗牛黏液的主要成分是水；正是黏蛋白（糖蛋白）和复杂的碳水化合物赋予了它那种黏稠的质地。除了化妆品领域，这种黏液在药物输送方面也具有巨大潜力。2020年，科学家发现将普通花园蜗牛的黏液与金纳米颗粒结合，有助于加速小鼠的伤口愈合，并表现出抗炎特性。
Most relevant to this latest paper is a 2023 study on garden snail slime that identified three distinct types of secreted mucus: a hydrating version to protect its skin, one that acts as an adhesive glue, and a third that serves as a lubricant so the snail can more easily glide across a surface.
与这篇最新论文最相关的是2023年一项关于花园蜗牛黏液的研究，该研究确定了三种不同类型的分泌黏液：一种用于保护皮肤的保湿型黏液，一种充当黏合剂的胶水型黏液，以及第三种作为润滑剂的黏液，使蜗牛能更轻松地在表面滑行。
The team focused their research efforts on the grove snail/lemon snail (Cepaea nemoralis), which they deemed well-suited as subjects because the snails secrete five different kinds of mucus with distinct functions. As with the garden snails, there is one that acts as a lubricant to help with locomotion and an adhesive mucus to help the snail stick to various surfaces. Then there’s a mucus layer known as the epiphragm that the snail secretes when it hibernates in winter, which contains calcite and effectively seals the shell to protect the snail from predators and harsh环境 conditions.
该团队将研究重点放在了林地蜗牛（Cepaea nemoralis）上，他们认为这种蜗牛非常适合作为研究对象，因为它们能分泌五种功能各异的黏液。与花园蜗牛一样，其中一种作为润滑剂帮助移动，另一种作为黏合剂帮助蜗牛附着在各种表面上。此外，还有一种被称为“上隔膜”（epiphragm）的黏液层，这是蜗牛在冬季冬眠时分泌的，含有方解石，能有效密封壳口，保护蜗牛免受捕食者和恶劣环境的影响。
C. nemoralis also secretes two different kinds of protective mucus when disturbed. One is a sticky yellow mucus similar to that produced by certain mollusks that is highly resistant to breakage or tearing. The other is a bubbly substance scientists believe is secreted to smother small predators and/or wash them out of the shell.
林地蜗牛在受到干扰时还会分泌两种不同的保护性黏液。一种是类似于某些软体动物产生的黏性黄色黏液，具有极强的抗断裂或抗撕裂能力。另一种是科学家认为用于窒息小型捕食者和/或将其从壳中冲刷出去的泡沫状物质。
The researchers analyzed all five types of mucus using various techniques, including proteomics, X-ray fluorescence, X-ray diffraction, cryoscanning electron microscopy, and liquid chromatography. They found that all five kinds of mucus share a similar protein composition and that collagen IV is the main structural component. It’s the different quantities of protein and the addition of amorphous calcium carbonate (ACC) that determine a given mucus’s distinct mechanical properties.
研究人员利用蛋白质组学、X射线荧光光谱、X射线衍射、冷冻扫描电子显微镜和液相色谱等多种技术分析了这五种黏液。他们发现，这五种黏液具有相似的蛋白质组成，且IV型胶原蛋白是主要的结构成分。正是蛋白质含量的差异以及无定形碳酸钙（ACC）的添加，决定了特定黏液的独特机械性能。
The two defensive kinds of mucus had the highest number of proteins. Those results “indicate that these proteins are used to tune the degree of cross-linking and therefore their network density, which has an immediate effect on their mechanical properties,” the authors concluded. “Each mucus type shows a distinct and complex hierarchical structure that is influenced by the processing of the mucus material.” Furthermore, calcium “is actively secreted together with the mucus, serving as an ion source for cross-linking or a mineral precursor for reinforcement.”
这两种防御性黏液的蛋白质含量最高。作者总结道，这些结果“表明这些蛋白质被用于调节交联程度，从而调节其网络密度，这对它们的机械性能有直接影响”。“每种黏液类型都表现出一种独特且复杂的层级结构，这种结构受到黏液材料加工过程的影响。”此外，钙“与黏液一起被主动分泌出来，作为交联的离子源或增强材料的矿物前体。”