Function and Chemical Nature of Ice-Active Substances Associated with Antarctic Sea Ice Diatoms

与海冰硅藻有关的冰活性物质的功能和化学性质南极洲麦克默多湾的海冰硅藻，先前已被证明与细胞外冰活性物质（ias）有关，ias存在于冰血小板层和硅藻所在的凝结冰中。这些分子具有较大的分子量，似乎是糖蛋白。在温带水硅藻中还没有发现类似的分子，因此它们似乎具有与寒冷或冰冷环境有关的功能。先前的研究表明，它们广泛分布在南大洋，在夏季和冬季海冰中都有出现，并且与许多（如果不是全部的话）海冰硅藻有关。这项研究将研究有关这些不寻常物质的功能和化学性质的其他问题。初步证据表明，ias具有低温保护性能。其中一个目标是通过几种方法来探索这种可能性，包括ias在测试酶（LDH）和整个细胞中防止冻融损伤的能力，以及它们抑制冰再结晶的能力，这是植物研究中防冻活性的常用措施。已知ias与冰晶结合，因此为了更好地理解结合机制，额外的研究将试图确定它们结合的特定晶体面。研究的第三部分将利用质谱法、氨基酸测序和其他技术，试图更好地表征红外光谱中碳水化合物和蛋白质部分的化学性质。最后，将初步尝试培养针对ias的抗体，因为这些抗体将在确定这些分子的起源、季节性、相关性以及可能的功能方面有几种用途。ias代表了一种新型的冰结合分子，它不同于蛋白质和糖蛋白的鱼类抗冻液。由于它们在南极海冰群落中无处不在，而在温暖地区却没有，它们似乎在这些群落中发挥着重要作用。这些研究应该能回答一些关于这些分子性质的主要问题。此外，ias与鱼类防冻剂有一些共同的特性，因此了解它们的冰结合特性和化学结构将使我们更好地了解这类分子是如何与冰相互作用的。最后，与鱼类防冻剂不同，ias在自然界中大量生产，这可能使它们在其他应用中具有可行性。

Function and chemical nature of ice-active substances associated with sea ice diatomsSea ice diatoms of McMurdo Sound, Antarctica, have been previously shown to be associated with extracellular ice-active substances (IASs) that are present both in the ice platelet layer and congelation ice in which diatoms are found. These molecules have large molecular weights and appear to be glycoproteins. Similar molecules have not been found in temperate water diatoms, and so it appears that they have a function related to cold or icy environments. Previous studies have shown that they are widely distributed in the Southern Ocean, occur in both summer and winter sea ice and are associated with many if not all sea ice diatoms. The research will examine additional questions about the function and chemical nature of these unusual substances. Preliminary evidence suggests the IASs have cryoprotective properties. One goal is to explore this possibility using several approaches, including the IASs' ability to prevent freeze-thaw damage in a test enzyme (LDH) as well as whole cells, and their ability to inhibit the recrystallization of ice, which is a common measure of antifreeze activity in plant studies. The IASs are known to bind to ice crystals, and so to better understand the binding mechanism additional studies will attempt to determine the specific crystal faces to which they bind. A third part of the study will try to better characterize the chemical nature of the carbohydrate and protein moieties of the IASs, using mass spectrometry, amino acid sequencing and other techniques. Finally, initial attempts will be made to raise antibodies against the IASs, as these will have several uses in determining the origin, seasonality, relatedness and possibly the function of these molecules. The IASs represent a novel type of ice-binding molecule that is distinct from protein and glycoprotein fish antifreezes. Because of their ubiquity in the Antarctic sea ice communities and their absence in warmer regions, they appear to have an important role in these communities. These studies should answer some of the main questions about the nature of these molecules. In addition, the IASs share some properties with fish antifreezes, and so understanding their ice binding properties and chemical structure will make it possible to better understand how this family of molecules interact with ice. Finally, the IASs, unlike the fish antifreezes, are produced in large quantities in Nature, and this may make it feasible for them to be used in other applications.