MULLEM · MULtiple fission in micro-aLgaE: uncovering conserved Mechanisms

Cell division is fundamental to life, but its regulation differs greatly across eukaryotes. While most divide by binary fission, producing two daughter cells per cycle, many green micro-algae divide by multiple fission, where one cell produces several daughters. This strategy supports rapid proliferation when conditions are favourable. A central checkpoint, the commitment point, ensures that only sufficiently grown cells proceed to division.Despite its importance, the molecular basis of multiple fission remains largely unknown. Current models describe it as a size-dependent ""sizer–oscillator"" system, but the identity of key regulatory components is still unknown.The MULLEM project (MULtiple fission in micro-aLgaE: uncovering conserved Mechanisms) will fill this gap by combining comparative transcriptomics, functional genetics and evolutionary analyses. Time-resolved RNA-seq across three green microalgae (Chlamydomonas reinhardtii, Chlorella sorokiniana, Scenedesmus quadricauda) and a diatom out-group (Phaeodactylum tricornutum) will highlight conserved candidate genes. These will be functionally validated through loss-of-function studies, complementation assays and live-cell imaging in Chlorella and Chlamydomonas. Double mutant analyses in Chlamydomonas will then reconstruct regulatory hierarchies, delivering the first molecular framework for multiple fission control.By revealing the molecular drivers of multiple fission, MULLEM will advance our understanding of eukaryotic division strategies and open new avenues to exploit multiple fission for sustainable biotechnology. The fellowship will strengthen the fellow’s expertise in algal genetics and comparative genomics, providing a strong platform for future independent research leadership.""