In vivo labelling of functional ribosomes reveals spatial regulation during starvation in Podospora anserina

BACKGROUND: To date, in eukaryotes, ribosomal protein expression is known to be regulated at the transcriptional and/or translational levels. But other forms of regulation may be possible. RESULTS: Here, we report the successful tagging of functional ribosomal particles with a S7-GFP chimaeric protein, making it possible to observe in vivo ribosome dynamics in the filamentous fungus Podospora anserina. Microscopic observations revealed a novel kind of ribosomal protein regulation during the passage between cell growth and stationary phases, with a transient accumulation of ribosomal proteins and/or ribosome subunits in the nucleus, possibly the nucleolus, being observed at the beginning of stationary phase. CONCLUSION: Nuclear sequestration can be another level of ribosomal protein regulation in eukaryotic cells.This may contribute to the regulation of cell growth and division.