Changes in relative abundance (% of T0) of symbiotic P. bursaria (A), of the cell line with reduced symbiotic algae (B), and of the aposymbiotic (without symbionts) cell line (C) 5 h after exposure to simulated UVR+PAR (photosynthetically active radiation); red bars (left) indicate the relative abundance in the control (i.e., darkness) and orange bars (right) in the UVR treatment; results are reported as the means ± standard deviations for three independent experiments; asterisk indicates a significant difference between control and treatment (p<0.05).