Subventions et des contributions :

Subvention ou bourse octroyée s'appliquant à plus d'un exercice financier. (2017-2018 à 2022-2023)

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.