Most organisms are exposed to daily light–dark cycles and exhibit rhythms in fundamental biological processes, such that they occur at optimal times of the day.
In the diatom Phaeodactylum tricornutum, we recently identified the first component of the circadian clock system—the bHLH-PAS protein RITMO1—and demonstrated its role in regulating key processes such as cell fluorescence, photosynthesis, and gene expression. We are currently using RITMO1 as a starting point to identify additional components of the diatom circadian clock, alongside characterizing photoreceptors in the input pathways that contribute to its synchronization with the environment.
Physiological analyses of clock mutants will help assess the significance of circadian timing mechanisms for diatom biology. We are investigating the role of diatom photoreceptors and the circadian clock in photoperiodism—the genetic adaptation to latitude and seasonal variations in day length.
Through this research, combined with our participation in the Tara Polar Expedition, we aim to advance the understanding of the mechanisms that regulate diatom seasonal activities in the Arctic Ocean and explain their ecological dominance in this extreme environment.