[Film] Step inside a cell of the snow alga Sanguina nivaloides and see how extraordinarily adapted its architecture is to living in the snowpack. The first film shows how state-of-the-art electron microscopy methods (known as FIB-SEM, meaning focused ion beam scanning electron microscopy) available at Grenoble’s IRIG institute have enabled us to see cells from every angle. The second film shows cellular organization in color. The nucleus containing the genetic material is visible in blue. The chloroplast where photosynthesis takes place is in green. It captures atmospheric CO2 in a central zone called the pyrenoid, shown in gray. This CO2 is used to make sugars, which polymerize into starch, a giant sugar reserve shown in violet. This starch is at the ends of protuberances that decorate the surface of the chloroplast. This sugar is available to the mitochondria, in yellow, a cellular structure that provides Sanguina with energy during the night. Finally, the cell is filled with lipid droplets, visible in red, which form a carbon reserve for spending long months in the snow… Thanks to this work, published in the international journal Nature Communicationsat the end of 2023, we’re beginning to better understand how these tiny cells can thrive in the unique environment of snow!