Snow algae: life cycles, motility & community structure

雪藻：生命周期、运动性

• 批准号: RGPIN-2017-04904
• 负责人: Quarmby, Lynne
• 金额: $ 1.89万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=711287
• 关键词: Snow; algae; life; cycles; motility

An untapped gold mine of fascinating cell biology is growing on the surfaces of alpine snowfields. Cold-loving unicellular algae colonize the snow and support a rich microscopic community that blooms during the melt season. The green algae produce a protective red pigment, turning the snow green, orange or red. Because it reflects less solar radiation than white snow, coloured snow causes an increase in local temperature, more melting and more algal growth. As the extent and seasonal duration of snow and ice diminishes with global warming, there are indications of algal blooms on an increasing fraction of remaining snowfields. We know little about these algal-based communities that thrive in an extreme environment dramatically impacted by climate change and possibly amplifying global warming. Ultimately, this research program will discover how fresh snow is colonized and how cellular interactions between species support life in a nutrient poor, cold habitat. We will learn how the algae use their cilia (whip-like cellular appendages), whether to follow the rivulets of snowmelt upstream to the light; to attach the cell to a mucilage-based community; or to recognize and hold tight to mates. We will learn how sexual and asexual cell division and the formation of spores produce blooms on the snow. Also on the long-term horizon, we will test the hypothesis that the fixed carbon, complex metabolites, and nutrients captured and synthesized on the surface of the snow provide important inputs to the soil of alpine environments. Our first objective will be to determine the species of algae, fungi & other microbes that live on local alpine snowfields. Using fluorescence-activated cell sorting (FACS), DNA sequencing, and microscopic observations, 3 MSc students and I will establish the diversity of microbial communities on local alpine snowfields. We will learn how those communities develop over the course of a season and how they vary year to year. Gene expression studies will provide a foundation for learning how the various organisms work together. The second objective is to work out the enigmatic life histories of snow algae, using both field experiments and lab studies in our well-equipped cell biology laboratory. Finally, our third objective is to discover how algae arrive afresh on the surface of the snow each spring. Do some arrive on the wind, or with the snow or do they all swim up from the soil below? Built into the research program are training opportunities for 6 new graduate students, along with 3 undergraduate students and several citizen-scientists every year. The research program will help us understand the role played by these algae in accelerating the melting of alpine snowfields in the context of global warming. We will provide the foundational cell biology for a globally significant microbial community. As happens in discovery science, we may also uncover novel cellular mechanisms of unforeseen value.

高山雪原的表面上正在生长着一座未开发的令人着迷的细胞生物学金矿。喜冷的单细胞藻类在雪上繁衍生息，并支持在融化季节开花的丰富的微观群落。绿藻产生一种保护性红色素，使雪变成绿色、橙色或红色。由于彩色雪比白雪反射的太阳辐射少，因此会导致局部温度升高、融化更多、藻类生长更多。 随着全球变暖，冰雪的范围和季节持续时间不断减少，有迹象表明，剩余雪地中藻类大量繁殖。我们对这些以藻类为基础的群落知之甚少，它们在受到气候变化严重影响并可能加剧全球变暖的极端环境中茁壮成长。 最终，该研究项目将发现新鲜的雪是如何定殖的，以及物种之间的细胞相互作用如何在营养贫乏、寒冷的栖息地中维持生命。我们将了解藻类如何使用纤毛（鞭状细胞附属物），是否沿着融雪的小溪逆流而上，到达阳光；将细胞附着到基于粘液的群落上；或者认识并紧紧抓住伴侣。我们将了解有性和无性细胞分裂以及孢子的形成如何在雪上产生花朵。同样从长远来看，我们将检验这样一个假设：雪表面捕获和合成的固定碳、复杂代谢物和养分为高山环境的土壤提供了重要的输入。 我们的首要目标是确定生活在当地高山雪原上的藻类、真菌和其他微生物的种类。我和 3 名硕士生将利用荧光激活细胞分选 (FACS)、DNA 测序和显微镜观察来确定当地高山雪原微生物群落的多样性。我们将了解这些社区如何在一个季节中发展以及它们每年如何变化。基因表达研究将为了解各种生物体如何协同工作提供基础。第二个目标是通过我们设备齐全的细胞生物学实验室的现场实验和实验室研究来弄清楚雪藻神秘的生命史。最后，我们的第三个目标是发现每年春天藻类如何重新到达雪的表面。有些是乘风而来，还是随雪而来，还是都是从下面的土壤里游上来的？研究计划每年为 6 名新研究生、3 名本科生和几名公民科学家提供培训机会。 该研究计划将帮助我们了解这些藻类在全球变暖的背景下加速高山雪原融化所发挥的作用。我们将为全球重要的微生物群落提供基础细胞生物学。正如发现科学中所发生的那样，我们还可能发现具有不可预见价值的新细胞机制。