Description du sujet de thèse

Role of rad51 proteins in mitotic interhomolog recombination in diatoms.
This PhD project aims to investigate the molecular basis of unusual interhomolog homologous recombination (IH-HR) observed in diatoms—key microalgae in marine ecosystems. Unlike most eukaryotes, diatoms display high levels of IH-HR during mitosis, a process typically suppressed to avoid deleterious genome rearrangements. The goal is to identify the molecular factors responsible for this phenomenon, focusing particularly on the role of the recombinase RAD51.
The PhD candidate will develop mutant lines of Phaeodactylum tricornutum to test the role of different RAD51 family members and their specific variants in recombination template choice. They will use systems to detect IH-HR and sister chromatid exchange, as well as genotoxic stress assays. The project will also include targeted mutational analysis of key RAD51 amino acids involved in DNA binding and mismatch tolerance.
This work is part of a broader effort to elucidate DNA repair mechanisms in microalgae and improve our understanding of the balance between genome stability and genetic variability in marine photosynthetic organisms.
Main Tasks:
• Generate RAD51 knock-out/knock-down mutants and other early HR factor mutants.
• Assess the impact of these perturbations on HR template choice and DNA repair.
• Investigate the effect of targeted RAD51A mutations on recombination template selection.

Contexte de travail

The project will be conducted within the PhytoGenomics team, led by Chris Bowler, in a collegial and supportive environment (ibens.ens.fr). The lab has a strong tradition of research in diatom biology, especially in genomics and cell biology. The team currently includes 3 PhD students, 3 postdocs, 1 assistant professor, 1 CNRS researcher, and 1 CNRS engineer. Research focuses on how environmental factors influence genome structure and dynamics. The PhD project will be supervised by Petra Bulankova, CNRS researcher and PI of the l'ERC Diatomic.
The Institute of Biology of the École Normale Supérieure (IBENS) is an international, multidisciplinary research centre located in the Latin Quarter in central Paris, with easy access to public transportation (RER, metro, bus). IBENS is a joint CNRS/Inserm/ENS unit comprising approximately 320 members across 29 research teams and is committed to promoting diversity and inclusion.

Contraintes et risques

None