Cold Adaptations of Carbon Metabolism in Antarctic Phototrophic Microorganisms

研究生物系统冷适应的分子机制对于理解地球上物种的进化和生态相互作用具有内在的重要意义。在南极洲的干旱山谷地区，一个完整的微生物生态系统生活在冰冻的砂岩中和永久被冰覆盖的湖泊中。维斯塔尔建议确定嗜冷光养生物(适应低温的蓝藻、藻类和光合细菌)在其DNA中是否具有独特的核苷酸和氨基酸序列，以及光合作用中的一个关键的二氧化碳固定酶，以解释该酶在零下温度下的功能。从之前的奖项(探索性研究小额赠款)中，维斯塔尔确定来自嗜冷蓝藻的这种关键酶具有独特的光合作用特性，这可能与其这种特殊的二氧化碳固定酶的分子结构有关。利用分子生物学的最新方法，将从干燥山谷湖泊的砂岩和藻垫中选择性地分离出真正的嗜冷光养细菌。如果这些南极嗜冷菌在它们的DNA和酶中拥有独特的序列，这些信息将为了解生物物种的冷适应机制以及它们与其他温带物种的进化关系提供新的见解。

Studying the molecular mechanisms of cold-adaptation of biological systems is intrinsically important to understand evolution and ecological interaction of species on Earth. In the Dry Valley region of Antarctica, a complete microbial ecosystem lives within sandstone at freezing temperatures and in permanently ice-covered lakes. Vestal proposes to determine whether psychrophilic phototrophs (cold-adapted cyanobacteria, algae, and photosynthetic bacteria) possess unique nucleotides and amino acids sequences in their DNA and a key CO2-fixing enzyme in photosynthesis to account for the enzyme's function at sub-zero temperatures. From a previous award (Small Grant for Exploratory Research), Vestal determined that this key enzyme from a psychrophilic cyanobacterium has unique photosynthetic properties that may be related to its molecular structure of this particular CO2-fixing enzyme. Using the latest methods of molecular biology, true psychrophilic phototrophs, which will be selectively isolated from sandstone and algal mats from Dry Valley lakes, will be studied. If these Antarctic psychrophiles possess unique sequences in their DNA and enzymes, the information would provide new insight into the mechanism of cold-adaptation of biological species and their evolutionary relatedness to other temperate species.