(A and B) Representative micrographs of native (A) or low-pH-treated (B) SMBV particles. Unopened particles are denoted with stars, and those with visible cracks are marked with arrows. One particle in (B), marked with a square, is clearly empty (lacks the internal density of the nucleocapsid), but cracks in the capsid are not visible, as that vertex is not contained within the micrograph. Particles such as these were counted as open when generating the percentages of open particles (POP).
(C) POP following treatment at various pH.
(D) The POP of SMBV particles incubated at elevated temperatures.
(E–H) Bubblegram images of two different native GV particles revealing star-shaped radiation damage patterns caused by the starfish complex (highlighted in F and H). (I and J) Final micrographs in bubblegram series of two different low-pH-treated SMBV particles. Note the lack of any star-shaped radiation damage patterns. See also Figure S1.