Snow algae: life cycles, motility & community structure

在高山雪地的表面上，一座尚未开发的迷人的细胞生物学金矿正在生长。喜欢寒冷的单细胞藻类在雪中定居，并支持在融化季节盛开的丰富的微生物群落。绿藻产生一种保护性的红色色素，将雪变成绿色、橙色或红色。因为与白雪相比，彩色雪反射的太阳辐射更少，所以它会导致当地气温上升，更多的融化和更多的藻类生长。随着冰雪的范围和季节性持续时间随着全球变暖而减少，有迹象表明，在剩余的雪地中，藻类水华的比例越来越大。我们对这些以藻类为基础的群落知之甚少，它们在极端环境中茁壮成长，受到气候变化的巨大影响，并可能放大全球变暖。*最终，这项研究计划将发现新鲜的雪是如何被殖民的，以及物种之间的细胞相互作用如何在营养贫乏、寒冷的栖息地维持生命。我们将学习藻类如何使用纤毛(鞭状细胞附属物)，是顺着积雪融化的小溪逆流而上到达光线；是将细胞附着在以粘液为基础的群落上；还是识别并紧紧抓住配偶。我们将学习有性和无性细胞分裂和孢子形成是如何在雪地上开花的。同样在长期地平线上，我们将检验这样的假设，即雪表面捕获和合成的固定碳、复杂的代谢物和营养物质为高山环境的土壤提供了重要的输入。*我们的第一个目标是确定生活在当地高山雪地上的藻类、真菌和其他微生物的种类。利用荧光激活细胞分类(FACS)、DNA测序和显微镜观察，我和3名理科硕士学生将在当地高山雪地上建立微生物群落的多样性。我们将学习这些社区在一个赛季的过程中是如何发展的，以及它们每年是如何变化的。基因表达研究将为了解各种生物如何协同工作提供基础。第二个目标是利用现场实验和我们设备齐全的细胞生物学实验室的实验室研究，得出雪藻神秘的生活史。最后，我们的第三个目标是发现藻类是如何在每年春天重新出现在雪地表面的。有些是随风而来的，还是随雪而来的，还是都是从下面的土壤中游上来的？该研究计划包括每年为6名研究生、3名本科生和几名公民科学家提供的培训机会。*该研究计划将帮助我们了解在全球变暖的背景下，这些藻类在加速高山雪地融化方面所起的作用。我们将为一个具有全球意义的微生物群落提供基础细胞生物学。就像发现科学中发生的那样，我们还可能发现具有不可预见的价值的新的细胞机制。

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.