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The Ostreococcus circadian clock

The aim of this project was to investigate the relationship between components of the Ostreococcus circadian clock. The circadian clock is a complex network of transcriptional and translational feedback loops with many components, which allows organisms to anticipate regular changes in their environment. Ostreococcus tauri is the simplest eukaryotic organism which is ideal for studying the core components of the circadian clock.


TEM of Ostreococcus, Eikrem and Throndsen University of Oslo

There are two genes which are found in the circadian clock in higher plants which are also present in the simpler Ostreococcus circadian clock: Timing of Cab expression1 (TOC1) and Circadian Clock Associated1 (CCA1). There has been an indication in unpublished results which suggests that the basic helix-loop-helix (bHLH) gene in Ostreococcus affects CCA1 transcription which means that it may be part part of its circadian clock. Chromatin immunoprecipitation (ChIP) and quantitative polymerase chain reaction (qPCR) were used to investigate the relationship of the TOC1 and bHLH genes with CCA1 in Ostreococcus. Western blots were used to confirm the presence of the TOC1 and bHLH proteins in transgenic plant lines. Then DNA associated with the proteins of interest was isolated using ChIP and enrichment for different genomic loci including CCA1 was quantified using qPCR. We showed that the TOC1 and bHLH genome in Ostreococcus is enriched for TOC1 and CCA1.

This project was supervised by Dr.Isabelle Carre