Molecular mechanisms of biological timekeeping. Gerben joined the University of Edinburgh in 2008 for his postdoctoral with Andrew Millar at the Centre for Systems Biology, where he contributed to the discovery of non-transcriptional circadian rhythms across eukaryotic cell types. He then secured a University Research Fellowship from the Royal Society, London, to continue to study cellular timekeeping at the Institute of Molecular Plant Science. Gerben's lab employ the minimal model cells of Ostreococcus tauri to identify fundamental cellular mechanisms underlying circadian timing across life. Gerben van Ooijen van Ooijen Lab Website Lab members Dr. Uma Jayachandran, Dr. Ana Belen Romero Losada, Dr. Apple Chew, Dr. Natalie Rogers, Hanhan Zhang, Selen Dinge and Irene Aldazabal Research Circadian rhythms are a fundamental feature of life, and circadian disruption increases the risk of infectious diseases as well as the risk of metabolic syndrome, cardiovascular disease, depression, and even some types of cancer. The clear importance of our body clock for health warrants a full understanding of the mechanisms behind timekeeping of cells: circadian rhythms are ultimately a culmination of individual cellular oscillators. In the living cell, virtually nothing stays the same over the course of a day.We study circadian timekeeping on the cell and molecular levels using the minimal model cells of Ostreococcus tauri. These green algal cells have only ~8000 genes, similar to yeast, but unlike yeast they have a strong circadian clock that is coupled to the cell cycle as it is in human cells. Evidence from my lab indicates that the blueprint of cellular circadian organisation translates well from this 'green yeast' to human cells: in 2011 we showed that pharmacological treatments affect the clock in human cells and Ostreococcus identically. We revealed a circadian rhythm in cellular redox state that was identical in Ostreococcus, human cells, and other rhythmic life. In 2016, we revealed circadian oscillations in ion concentrations in Ostreococcus, human, mouse, and fungi. In 2020, we reported that the methyl cycle affects circadian rhythms identically in human cells, Ostreococcus, and more12. Out lab currently continues along these lines, by identifying novel mechanisms of circadian timekeeping in model cells to then test those observations in other eukaryotic cells, such as mammals or plants.Most of our current projects focus on the generation and functional relevance of circadian rhythms in intracellular potassium and magnesium concentrations. These ion rhythms functionally affect some of the most fundamental aspects of cell biology, including translation rate, cytoplasmic conductivity, proteostasis, and cell proliferation. Image Figure Legend3-Dimensional Structured Illumination Microscopy (3D-SIM) imaging of two Ostreococcus tauri cells upon immuno labelling (green) of a STREP-tagged cytosolic protein. Red: chlorophyll autofluorescence. Blue: nuclei. Selected publications Kay H, Grünewald E, Feord HK, Gil S, Peak-Chew SY, Stangherlin A, O'Neill JS, van Ooijen G. (2021) Deep-coverage spatiotemporal proteome of the picoeukaryote Ostreococcus tauri reveals differential effects of environmental and endogenous 24-hour rhythms. Communications Biology 2021 Sep 30;4(1):1147Fustin JM, Ye S, Rakers C, Kaneko K, Fukumoto K, Yamano M, Versteven M, Grünewald E, Cargill SJ, Tamai TK, Xu Y, Jabbur ML, Kojima R, Lamberti ML, Yoshioka-Kobayashi K, Whitmore D, Tammam S, Howell PL, Kageyama R, Matsuo T, Stanewsky R, Golombek DA, Johnson CH, Kakeya H, van Ooijen G, Okamura H. (2020) Methylation deficiency disrupts biological rhythms from bacteria to humans. Communications Biology 3: 211Feeney KA, Hansen LL, Putker M, Olivares-Yañez C, Day J, Eades LJ, Larrondo LF, Hoyle NP, O'Neill JS, van Ooijen G (2016) Daily magnesium fluxes regulate cellular timekeeping and energy balance. Nature 532: 375-9.Edgar RS*, Green EW*, Zhao Y*, van Ooijen G*, Olmedo M*, Qin X, Xu Y, Pan M, Valekunja UK, Feeney KA, Maywood ES, Hastings MH, Baliga NS, Merrow M, Millar AJ, Johnson CH, Kyriacou CP, O'Neill JS, Reddy AB. (2012) Peroxiredoxins are conserved markers of circadian rhythms. Nature, 485: 459-64. *equal contribution O’Neill JS*, van Ooijen G*, Dixon LE, Troein C, Corellou F, Bouget FY, Reddy AB, Millar AJ (2011). Circadian rhythms persist without transcription in a eukaryote. Nature, 469: 554-58. *equal contribution This article was published on 2026-04-23
