Fig. 5

R-bodies transition between two states. a Type 51 R bodies reversibly transition between a rolled state at neutral pH and a tube state at low pH by the extension of the ribbon from the center of the coil. The state depicted in the middle is transient. b This transition is visible macroscopically; coiled R bodies sediment and extended R bodies remain in solution. c When an R-body-containing bacterium is ingested by a sensitive strain of paramecium after being shed by a “killer” strain, the extension of the R body is triggered by the acidic environment of the food vacuole. Extension causes the rupture of the bacterium and the food vacuole, releasing co-expressed toxins that ultimately result in the death of the sensitive paramecium. Images adapted from [89]