Skip to main content
. Author manuscript; available in PMC: 2021 Oct 29.
Published in final edited form as: Nat Microbiol. 2021 Apr 29;6(6):769–782. doi: 10.1038/s41564-021-00897-w

Fig. 2. Non-symbiotic microalgae are removed by expulsion.

Fig. 2

a Only the symbiont was maintained in a LAMP1-positive symbiosome, as early as 6 hpi, while the other microalgae showed no, or only slight, LAMP1 staining. LAMP1 (magenta); nuclei (cyan); microalgae (white). (n=4 with 30 larvae per n). Scale bar represents 10 μm. b During live imaging of larvae, symbionts were rarely expelled and replicated within the host endoderm. M. gaditana, N. oculata, C. velia, and beads were all expelled at some point during 48 hours of imaging. For the symbiont 13 larvae were imaged with a total of 27 algae; M. gaditana: 7 larvae/19 microalgae; N. oculata: 7 larvae/13 microalgae; C. velia: 8 larvae/12 microalgae; beads: 11 larvae/28 beads. Expulsion was significantly higher in N. oculata-containing larvae (p = 0.0077) than in symbiont-containing larvae. Error bars represent mean ± 95 % CI. c Exemplary images during live imaging. Timestamps indicate time after the start of imaging (hh:mm:ss), which coincides with 24 hours post infection. Stills are DIC and red autofluorescence of microalgae photosynthetic pigments, scale bar represents 30 μm, inserts are zoomed 3-fold. For corresponding Supplementary Videos see Supplementary Videos S6-10. d Live imaging during 12 hours after 1-hour infection reveal low levels of symbiont expulsion but significantly higher levels of expulsion of M. gaditana (p = 0.0000058) and N. oculata (p = 0.000021), also compared to compared to C. velia (p = 0.0014, p = 0.0035, respectively). Microalgae that were not expelled during the time of observation were set to 12 for the quantification. Error bars represent mean ± 95 % CI. e Time to the first expulsion was highly stochastic during this time with significant differences between the symbiont and M. gaditana (p = 0.0025) and N. oculata (p = 0.0052) as well as between M. gaditana and C. velia (p = 0.036). f M. gaditana in particular (p = 0.00010), but also N. oculata (p = 0.0049) were frequently reacquired during the observed period compared to the symbiont. d, e, f: n=4 with ~10 larvae each. Statistics are based on a two-sided generalized linear mixed model of the data with pairwise p-values adjusted with the Tukey method. *P < 0.05, **P < 0.01, ***P < 0.001.