Ansart A, Nicolai A, Vernon P, Madec L
Universite de Rennes 1, UMR 6553 Ecobio, Rennes Cedex, France.
Cryo Letters. 2010 Jul-Aug;31(4):329-40.
The supercooling ability of adults and eggs of the partially freezing tolerant land snail Cornu aspersum remains limited to high subzero temperatures (ca. -5 degree C) whatever the conditions, suggesting the presence of ice nucleating agents (INAs). In this study, we investigated the nucleation activity of the digestive tract of adult snails, eggs and their direct environment: food, faeces and soil. The mucous ribbon always present in the distal intestine of adults exhibited a heat-sensitive (i.e. organic) nucleation activity, close to that of the entire snails during dormant states (aestivation and hibernation). However, a microbial nature of these INAs could not be established in inactive snails. The food provided to active snails contained ice nucleating bacteria, which followed the digestive tract to be found in the intestine and in the faeces, but with a decreasing concentration along the transit. Eggshells also presented a heat-sensitive nucleation activity, which could be related to its structure. Moreover, eggs are laid directly in the soil which contained both organic and mineral INAs. This study is the first to demonstrate the implication of organic INAs in the cold hardiness of a terrestrial gastropod.
无论条件如何，部分耐冻陆地蜗牛玉米蜗牛（Cornu aspersum）的成体和卵的过冷却能力仍局限于较高的零下温度（约-5摄氏度），这表明存在冰核剂（INA）。在本研究中，我们调查了成年蜗牛、卵及其直接环境（食物、粪便和土壤）消化道的成核活性。成年蜗牛远端肠道中始终存在的黏液带表现出对热敏感（即有机）的成核活性，与休眠状态（夏眠和冬眠）期间整个蜗牛的成核活性相近。然而，在不活跃的蜗牛中无法确定这些冰核剂的微生物性质。提供给活跃蜗牛的食物中含有冰核细菌，这些细菌沿着消化道在肠道和粪便中被发现，但随着在消化道中的移动浓度逐渐降低。蛋壳也表现出对热敏感的成核活性，这可能与其结构有关。此外，卵直接产在含有有机和无机冰核剂的土壤中。本研究首次证明了有机冰核剂在陆地腹足动物抗寒能力中的作用。
