New research from the Helliwell, Wheeler, Brownlee groups sheds light onto how diatoms, an important group of marine phytoplankton, are able to sense their external environment and provides new insights into the evolution of electrical excitability in eukaryotes more generally. Diatoms exhibit electrical activity in the form of fast all-or-nothing action potentials, which closely resemble those found in animal nerves and muscles. However, while action potentials are vital for communication in nerves and muscles, their roles and underlying cellular mechanisms in unicellular photosynthetic cells are poorly understood.
The new study by Helliwell and Chrachri et al., published in this week’s issue of Current Biology demonstrates that diatoms generate action potentials via a novel class of ion channels: EukCatAs. By using cutting-edge techniques for targeted gene knockout via CRISPR-Cas9 genome editing, Helliwell et al. show that these channels play an important role in cell signalling. Knock-out mutants were also impaired in their ability for gliding motility: a specialised way certain diatoms move that is vital for finding nutrients and optimising growth conditions. The study reveals that diatoms have evolved novel signalling mechanisms for environmental sensing in the oceans.