Phage DNA replication and cyanobacterial DNA degradation in resistant cyanobacteria. Intracellular phage DNA (A, C, and E) and cyanobacterial DNA (B, D, and F) levels were monitored for 10 or 12 h after infection with 3 generalist phages: Syn9 (A and B), P-TIM40 (C and D), and S-TIM4 (E and F) (n = 3). Longer term assessment (144 h) is shown after infection by Syn9 of sensitive Synechococcus WH8102 (G) and resistant Synechococcus WH5701 (H). Results in G and H are representative of 4 independent experiments. Phage DNA was measured by qPCR for g20 (portal protein gene) and is relative to maximal levels in the sensitive strain. Cyanobacterial DNA was measured by qPCR for rbcL (RuBisco gene) and is relative to levels immediately after infection (at t0). Levels during interactions with resistant Synechococcus (Syn.; orange), resistant Prochlorococcus (Pro.; green), and sensitive Synechococcus (blue) strains are shown. Results with specialist phages are shown in SI Appendix, Fig. S3.