[Department of Ocean Science] PhD Qualifying Examination Defense Seminar: The Pulse of Giant Viruses in the South China Sea: Diurnal Rhythms, Host Responses, and Co-evolutionary with Ostreococcus
 

Abstract:

Viruses are ubiquitous and crucial players in marine ecosystems, profoundly influencing microbial communities and biogeochemical cycles. The discovery of giant viruses has opened new frontiers in virology, revealing their significant presence and influence on unicellular eukaryotic hosts. Our understanding of giant viruses and their interactions with unicellular eukaryotic hosts is still developing. While environmental metagenomics has significantly expanded the discovery of new giant virus genomes, critical research gaps remain. Future research must focus on underrepresented environments, the in-situ behavior and infection strategies of giant viruses, and laboratory-based studies to dissect infection cycles, host defenses, and co-evolution. This work addresses these gaps through three avenues: first, analyzing metagenome-assembled genomes to reveal genomic adaptations to environmental conditions and using diel-resolved metatranscriptomics to understand how giant viruses temporally regulate infection dynamics in subtropical estuaries. Second, employing laboratory cultivation and gene expression analysis to study prasinovirus- Ostreococcus interactions, comparing transcriptional changes post-infection to understand viral infection mechanisms and host defense strategies. Third, investigating the co-evolution between Ostreococcus and the OEV2 virus through long-term co-cultivation, monitoring population dynamics, identifying mutations under selective pressure, and exploring genetic diversification via whole-genome sequencing and single-cell transcriptomics.