Assist.-Prof. Dr. Megan Sørensen

Photosynthetic endosymbioses have driven some of the most important evolutionary transitions in the history of life and continue to play a fundamental role in modern ecosystems. Megan Sørensen's research group leverages microbial eukaryotic systems, protists, to study the evolution and ecology of these important partnerships. 

The group combines diverse techniques, including single-cell molecular approaches, experimental evolution and field-based studies, to uncover how these partnerships are integrated at every level of their cellular biology, and how this enables coordination, and potential manipulation, between the partners. The overall research aim is to advance our fundamental understanding of the molecular mechanisms that underpin the emergence and maintenance of endosymbioses, and how, in rare cases, endosymbionts can evolve into permanent organelles. Megan was recently awarded an ERC Starting Grant.

The ciliate Paramecium bursaria hosts hundreds of green algae endosymbionts (from the Chlorella and Micractinium genera). Despite having synchronised cell cycles and vertical transmission of the endosymbionts, the partnership remains facultative. Meaning that the partners can be separated, cultured independently and the relationship re-established. We will utilise this capability and use this system to study how a photosynthetic endosymbiosis emerges and then stabilises. 

Species within the Paulinella genus of the Cercozoa contain a remarkable photosynthetic organelle known as the chromatophore. The chromatophore is derived from a cyanobacterium, and represents the only known primary plastid endosymbiosis outside the Archaeplastida. Critically, chromatophores were acquired much more recently than the canonical plastids of the Archaeplastida (~100 million years ago versus ~1.6 billion years ago), positioning Paulinella as a unique intermediary. We will use Paulinella as an exciting model system to investigate the transition from endosymbiont to organelle.