Antarctic Marine Archaebacteria; Biological Properties and Ecological Significance

Delong 9418442古细菌是原核生物中一个进化上截然不同的类群。 直到最近，古细菌才被认为只在几个不同的小生境中茁壮成长，包括非常热，非常咸，或严格厌氧的环境。 最近的研究表明，远洋海洋古细菌可以构成南极帕尔默站附近沿海沃茨南极原核生物生物量的主要部分（30%）。 由于帕尔默站外的表面沃茨产生了迄今为止最高的浮游古细菌生物量估计，这一地区是唯一适合研究这些不寻常的微生物。 拟开展的工作的主要目标是表征南极洲Anvers岛近海沃茨中浮游海洋古细菌的生态学意义、分布和丰度以及代谢和生理活动。 将利用分子生物学技术对南极海洋古细菌物种的时空丰度和变异性进行量化。 高度敏感，半自动化的方法将开发定量古细菌组和物种特异性核糖体RNA和DNA在现场样品。 为了更好地了解他们的生理活动，采用“王国特定”的代谢抑制剂的方法将被用来估计远洋古细菌总原核异养活性的贡献。 该项目将提供关于南极浮游古细菌的季节和空间变化的信息，这些古细菌可能构成南极沿海原核生物量的主要部分。 最后，本项目还将增进对南极沿海沃茨这些丰富的“古浮游生物”的生物地球化学活动和生态作用的了解，并可能为它们对独特的南极环境的具体适应提供线索。

Delong 9418442 Archaebacteria are an evolutionarily distinct group of prokaryotes. Until very recently, archaebacteria were thought to thrive only in a few disparate niches, consisting of either very hot, very salty, or strictly anaerobic environments. Recent studies show that pelagic marine archaebacteria can constitute a major fraction (30%) of Antarctic prokaryote biomass in coastal waters off Palmer Station, Antarctica. Since surface waters off Palmer Station have yielded the highest biomass estimates of pelagic archaebacteria to date, this area is uniquely suited for studing these unusual microorganisms. The main objective of the proposed work is to characterize the ecological significance, distribution and aboundance, and the metabolic and physiological activities, of pelagic marine archaebacteria in coastal waters off Anvers Island, Antarctica. Molecular biological techniques will be used to quantify the spatial and temporal abundance and variability of Antarctic marine archaebacterial species. Highly sensitive, semiautomated methods will be developed to quantify archaebacterial group and species-specific ribosomal RNA and DNA in field samples. To better understand their physiological activities, methods employing "kingdom-specific" metabolic inhibitors will be used to estimate the contribution of pelagic archaebacteria to total prokaryotic heterotrophic activity. The project will provide information on the seasonal and spatial variability of pelagic Antarctic archaebacteria, which can comprise a major fraction of Antarctic coastal prokarytoic biomass. Finally, this project will also enhance understanding of the biogeochemical activities and ecological roles of these abundant "archaeoplankton" in coastal Antarctic waters, and may provide clues as to their specific adaptations to the unique Antarctic environment.