Fig. 7: Transmission electron microscopy (TEM) images of putative virion formation in Symbiodiniaceae cells from bleaching colonies of the Pacific stony coral, Acropora hyacinthus, sampled during an in situ heat stress event.
From: Filamentous virus-like particles are present in coral dinoflagellates across genera and ocean basins
A–C Symbiodiniaceae cell with electron-dense viroplasm and putative extruding virions; (B) is a higher resolution of the boxed area from (A); (C) is an inset of (B). Double membranes are visible in (C) of some filaments (white arrowhead). Cross sections with electron-dense cores are indicated by black arrows. D–F and G–I show similar examples of a Symbiodiniaceae cell with putative exocytosis of virions into the cytoplasm. V indicates putative viroplasm; * indicates a cavity with coarse filamentous VLPs; black arrowheads highlight areas with putative virion exocytosis. The identity of these structures cannot be confirmed; other possibilities include viral nucleic acid strands being released for later assembly in the cytoplasm, host cell degradation of filamentous VLPs (visible in the electron-dense putative viroplasm) to recycle nucleic acids, or other non-viral intracellular structure.
