The Snow Alga Chlamydomonas nivalis: PhotosynthesisUnder the Greatest Extremes of High Light, UV-B Radiation and Low Temperature on Earth

雪藻，雪藻。它生长在永久的雪原上，生长在落基山脉的高山地带，这是一个由地球上最极端的环境条件组成的栖息地。除了在白天的冰冻温度下存活外，这种生物还在自然环境中发现的可见光和紫外线b辐射（UV-B； 280-320运行）的最高通量下进行光合作用。拟议的研究将量化这种核生物所经历的极端微环境，并将提供在如此恶劣条件下其光合作用性能的基线信息。利用多种便携式显微传感器和仪器，对含雪草种群的雪深剖面进行了温度、光、UV-B辐射、COz浓度和光合性能的同步环境测量。光合作用将在体外通过析氧和变光温度条件下进行测量。通过测量雪芯中i4C:O2的掺入，将获得碳固定的确证测量。通过在雪原上进行的排除试验，确定了W-B对柽柳种群和光合性能的影响。这些实验将为未来研究调节这种微生物在这种极端栖息地的适应和生存的分子机制奠定基础。

Vogelman 97-14268 The snow alga, Chlamvdomonas nivalis. grows on permanent snowfields and is found in the alpine zone of the Rocky Mountairm, a habitat that consists of some of the most extreme environmental conditions found on Earth. In addition to surviving diurnal freezing temperatures, this organism photosynthesizes under some clef the highest fluxes of visible light and ultraviolet-B radiation (UV-B; 280-320 run) found in a natural environment. The proposed research will quantify microenvironmcnta1 extremes experienced by this nucroorganism and will provide baseline information on its photosynthetic performance tinder such severe conditions. Using a variety of portable microscopic sensors and instruments, simultaneous er~virontnental measurements of temperature, light, UV-B radiation, COz concentrations add of photosynthetic performance will be made across snow-deplh profiles containing C. nivalis populations. Photosynthesis will be measured in 'vitro by oxygen evolution and under conditions of variable light avid temperature. Corroborative measurements of carbon fixation will be obtained by measuring incorporation of i4C:O2 within snow cores. Effects of W-B on C. nivaIis populations and photosynthetic performance verity be determined frown We exclusion experiments conducted on the snowfields. These experiments will establish a baseline for future studies of molecular mechanisms that regulate adaptation and survival of this microorganism in this extreme habitat.