SymbioScope: Assessing the ecological diversity and dynamics of symbiotic interactions in a key phytoplankton by automated high-content 3D microscopy

• Applicant: Dr. Marie Walde
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems ; Image and Language Processing, Computer Graphics and Visualisation, Human Computer Interaction, Ubiquitous and Wearable Computing ; Measurement Systems ; Virology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 464344344

Photosynthetic plankton (phytoplankton) are at the heart of global ecological and economic processes. While the revolution in environmental DNA and RNA sequencing provides the power to comprehensively assess plankton taxonomic and metabolic diversity, it conveys no information on the shapes, structures, and behaviour of cells and organisms. However, there is increasing evidence that biotic interactions, including symbioses (sensu lato) between plankton taxa, are major drivers of species and ecosystem ecology and evolution. To study phytoplanktonic symbioses in the environment remains challenging, due to their high morphological complexity. The lack of high-content quantitative techniques to recognize, describe, count, and assess the subcellular structures of phytoplankton extracted from the ocean is a major blind spot in plankton ecology.In the SymbioScope project, I propose to first, develop a technological workflow based on feedback automated fluorescence microscopy to quantitatively measure the subcellular structure and interaction landscape of microbial plankton with both, sufficiently high detail and throughput. I will then apply this new tool to assess the symbiotic complexity in Guinardia delicatula, (a dominant eukaryotic phytoplankton species offshore Roscoff) across its seasonal phenology. By automatically imaging, classifying, and quantifying hundreds of G. delicatula cells across seasons, it will for the first time become possible to quantify its symbiotic interactions with RNA and DNA viruses, prokaryotes, and other eukaryotes, and measure how the symbiotic landscape is changing over time and in response to biotic and abiotic environmental parameters. This project will fill a major technological gap in aquatic ecology and generate fundamental knowledge on the structure and dynamics of eukaryotic symbioses from the single cell to the population level. My profound expertise in bioimaging and microscopy, combined with the exceptional access to the world's largest marine protists collection at the host institute (providing the critical raw material for method development and validation) and a strong connection with partners at the EMBL in Heidelberg, together form a sound foundation for this innovative project to be a success.

• DFG Programme: WBP Fellowship
• International Connection: France
• Hosts: Dr. Nina Simon; Dr. Colomban de Vargas