Extended Data Fig. 5: Additon of salts induces dissociation-encystation, similar to gradual evaporation.
From: Clonal-aggregative multicellularity tuned by salinity in a choanoflagellate
(a-c) DIC images of C. flexa cells over a 6-day time course experiment where salinity was progressively increased 1-fold daily by the addition of seawater salts after 3 days of growth show that sheets dissociate and cells undergo morphological changes in hypersaline media. At the end of the 6-day time course, cells grown for 6 days at 1X salinity (a, no salinity increase) remain in multicellular sheets composed of flagellated cells (i) with a collar (green pseudocolour) and a flagellum (magenta pseudocolour). Under progressive salinity increase by salts addition, sheets dissociate into unicellular cysts (b-c). Cysts often lack a collar and a flagellum, and exhibit filopodia-like protrusions (pink arrowheads) after 2 days at 3X salinity (b) and after 1 day at 4X salinity (c). Scale bars in (i-iii): 10 µm. (d) Quantification of cell number over a 6-day time course where salinity was progressively increased 1-fold daily by the addition of salts after 3 days of growth. 1X salinity corresponds to 35 ppt. (e) Growth rate of cells over a 6-day time course experiment in d. Black circles represent mean values and error bars represent standard deviation. Mean values of each biological replicate are represented as diamonds. p-values in e by the Mann-Whitney U test. N = 2 biological replicates, two technical replicates each (n = 4). Figure related to Fig. 4f–i, m.
