FIG 2.

Impact of hcp on symbiosis establishment by FQ-A001. (A) Luminescence (Lum) of animals at 48 h after initial exposure to an inoculum containing either FQ-A001 (WT) or TIM416 (Δhcp) harboring the YFP expression plasmid pSCV38. The dashed line indicates the 95% tail of luminescence associated with animals within an aposymbiotic group, above which animals are scored as luminescent. Seventeen or 18 animals were used in each group. A Mann-Whitney test determined that the medians for luminescent animals within each group are not significantly different from those for other groups (α = 0.05). n.s., not significant (P > 0.05). The experiment was performed twice, with similar results. RLU, relative light units. (B) Number of crypt spaces per animal in panel A exhibiting YFP fluorescence. A Mann-Whitney test determined that the median for animals within each group was not significantly different from those for other groups (α = 0.05). (C) (Top) Images of a light organ containing fluorescently labeled strains of V. fischeri. In the merged image, crypt spaces that harbor V. fischeri populations are outlined by dotted lines and labeled according to crypt type. (Bottom) Strategy for visualizing the colonization state of the light organ by scoring crypt spaces according to strain type (white, empty; blue, CFP; green, YFP; striped pattern, CFP plus YFP). (D) Number of crypts exhibiting CFP and YFP fluorescence per squid. Squid were exposed to an inoculum in which CFP-labeled ES114 and the indicated FQ-A001-derived strain labeled with YFP (WT, FQ-A001; vasA_2, ANS2098; Δhcp, TIM416) were mixed evenly. A Kruskal-Wallis test determined significant differences among groups (P < 0.0001; H = 22.18), and Dunn’s multiple-comparison test was performed to test for significant differences between specific groups (****, P < 0.0001; ***, P < 0.001). The experiment was performed twice, with similar results. (E) Colonization states of light organs of the squid for which data are shown in panel D. Each row represents an individual animal. The asterisk indicates the light organ imaged in panel C.