Research Progress in Area 1 方向 ( 一 ) 課題進展 89 Abstract Cyanobacterial viruses (cyanophages) depend on cyanobacteria to replicate and therefore their infection process is also influenced by the daily light-dark (diel) cycle. Recently, Prof. Zeng’s team examined the diel infection patterns of the unicellular picocyanobacteria Prochlorococcus and Synechococcus. They found that cyanophages used three diel-dependent life-history traits when infecting their host cells in the dark. However, the underlying molecular mechanisms have not been explored. The research project lead by Prof. Zeng will give us a comprehensive picture of how cyanobacteria and cyanophages have coevolved to respond to the daily light-dark cycle. Their work will help reveal the molecular mechanisms by which the interactions of cyanobacteria and cyanophages are influenced by the daily lightdark cycle. Their work will demonstrate how cyanophages affect the host’s circadian rhythm, including cell cycle and carbon metabolism. Eventually, they will build a model to predict how the daily light-dark cycle drives cyanobacteria and cyanophage population dynamics in the South China Sea. Therefore, their research work is crucial to understand marine ecosystem health and safety. Research Activities and Progress • Carried out metatranscriptomic analysis of cyanophage transcripts from the North Pacific Subtropical Gyre; • Examined the impact of light-dark cycle on both cellular- and population-scale dynamics in multiple Prochlorococcus-phage systems; • Developed a light-driven population model, including both cellular growth and viral infection dynamics; • Tested the model against measurements of experimental infection dynamics with diel forcing. Key Findings • The significantly later peak expression times of late genes in cyanomyovirus field populations suggest that cyanophage infection of cyanobacteria is synchronized; • Model-data integration reveals that lightdependent adsorption can improve fits to population dynamics for some virus-host pairs; • The study presents a quantitative approach to integrate mechanistic models to reconcile Prochlorococcus-virus dynamics spanning cellular-to-population scales. Research Output Publication 1 Trained personnel 5 Diurnal Rhythms of Cyanophage Infections in the Oceans Prof. Qinglu Zeng The Hong Kong University of Science and Technology Fig 1. Comparison of the peak expression times of early, middle, and late genes in cyanomyovirus field populations (Chen et al. 2020 Microbiome)
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