Exosome secretion affects social motility in Trypanosoma brucei
Fig 12
Wild-type cells crawl over FCS but “escape” from exosomes.
(A) Wild-type cells were plated on semi-solid agar and incubated 3 days while projections fully developed. The cells at the edge of the projections were analyzed by time-lapse microscopy. (a) FCS (10μg) was placed at the edge of one projection (S3 Video); (b) exosomes (10 μg) were placed at another projection, and cell movement was monitored (S4 Video). The images taken from S3 Video (a) and S4 Video (b) are presented at the indicated time points following spotting of FCS or exosomes. Scale bar and time points of recording are indicated. (B) Colony morphology of wild-type cells and a mixture of wild-type and SmD1-silenced cells. Wild-type cells or a mixture of wild-type and SmD1 silenced cells (silenced for 2 days prior to plating) were plated, and the morphology of the colony was recorded after plating. (C) Time lapse microscopy: (a) The social motility of wild-type cells. Wild-type cells were monitored) S10 Video. The images taken from this video are presented at the indicated time points. (b) Effect of cells secreting exosomes on the social motility of wild-type cells. Wild-type and SmD1 silenced cells (silenced for 2 days prior to plating) expressing ZC3H41- GFP (green) were plated as described in Materials and Methods. S11 Video illustrates the effect of SmD1-silenced cells on the development of projections. The upper panel shows images that were taken from this video at the indicated time points. Scale bar and time points of recording are indicated. The lower panel (4X magnification) is at higher magnification showing the “balls” formed by these cultures. Images derived from (S12 Video) at the indicated time point are presented. Scale bar and time points of recording are indicated. (c) Wild-type cells were mixed with SmD1/Vps36 silenced cells (2 days prior to plating) expressing HIS2-RFP. The cells were monitored for 20 hr (S13 Video). The images taken from this video are presented at the indicated time points. Scale bar and time points of recording are indicated.