Fig. 4: The activation of PICMI₁₁₅ is helper phage specific.

a PICMI₁₁₅ DNA was less or not detected in Φ115 genetically related phages. DNA from viral particles were extracted and separated on SYBR Green stained gel and Southern blotted with an PICMI₁₁₅ or Φ115 probes. M: molecular marker (Smart ladder Eugentec). Uncropped gel and blots are provided as a Source Data file. Images are representative of two independent experiments. b An efficient induction of the satellite is specific to the helper phage Φ115. The Vibrio strain V115 carrying a Cm^R marked PICMI₁₁₅ was infected with the diverse phages at a MOI of 10 for the indicated time, PCR amplicon corresponding to the circular/concatemeric PICMI₁₁₅ were visualized on agarose gel. c The alpA, up1, and prim genes of PICMI₁₁₅ were observed to be upregulated early after infection with Φ115. In the experimental setup, Vibrio strain V115 was subjected to infection with either the pure Φ115 (c) or Φ27 (d). Utilizing qRT-PCR, the expression levels of the six genes from PICMI₁₁₅, as well as the flanking genes fis and zntR, and the housekeeping gene gyrA were assessed. Source data are provided as a Source Data file. Copy numbers were standardized to gyrA for each sample, and the fold change was determined by comparing samples collected at specified time points to the input samples taken immediately before introducing the phage. Bar charts show the mean ± SEM fold change from three independent experiments Individual data points from each experiment are represented by dots. At 15 min post-infection, one-tailed t-test result shows that only alpA, iolg, and prim induction by Φ115 result in a fold change >1 (p < 0.05).