Arctic Diatoms Glide at Record-Low Temperatures

Ice diatoms are small unicellular algae that have recently set a record for the coldest temperature at which a eukaryotic cell has been observed moving: −15 °C. Eukaryotic cells, found in animals, plants, and fungi, have a central nucleus protected by a membrane, which sets them apart from bacteria.

Diatoms are found throughout the world’s oceans and freshwater environments and play a crucial role as primary producers, forming the base of many aquatic food webs. In polar regions, ice diatoms are particularly important, sustaining life under the ice and contributing to spring blooms that fuel the ecosystem.

The study, recently published in PNAS and led by researchers at Stanford University, shows that these Arctic diatoms do more than just survive in freezing ice. They glide across it using a thin, sticky coating and tiny molecular motors similar to the proteins that allow human muscles to contract. The coating acts like a rope, helping the diatoms pull themselves forward even at extremely low temperatures. Related diatoms from non-polar waters cannot move on ice because they do not adhere to it.

In this study, researchers collected ice cores from the Chukchi Sea, north of the Bering Strait between Alaska and Siberia, and directly imaged the diatoms inside the ice with a microscope aboard the research vessel. Back in the lab, they recreated the icy environment with thin ice layers and microchannels, showing that the diatoms can still move even under extreme cold.

Compared to related diatoms from warmer waters, Arctic diatoms moved faster, suggesting an evolutionary advantage in their harsh environment. How their molecular motors continue to function at subzero temperatures remains an open question for future research.

This discovery highlights the remarkable adaptability of microscopic life in extreme environments and provides new insights into how diatoms navigate ice and influence polar ecosystems and the global carbon cycle.

Léa Zinsli, PolarJournal