Fig. 7

Fig. 7

a, b Schematics showing the site of microinjection within a 2 dpf embryo and the evolving fluorescence of pHrodo-containing DOPC:4 → 3 liposomes within the tail region of a wildtype (AB/TL) embryonic zebrafish, over time. The fluorescence intensity of pHrodo increases >100-fold in mildly acidic environments (e.g. late endosomes/lysosomes, pH < 6) and is, therefore, particularly apparent within SECs—cells with exceptionally high lysosomal activity. c Tissue level views of evolving pHrodo-associated fluorescence over time either in the absence of UV irradiation and following in situ UV irradiation (15 min, 370 ± 7 nm, 2.4 J cm⁻²). In the absence of UV irradiation, pHrodo-associated fluorescence is observed within a small number of cells within the CHT of the embryo (white arrowheads). Liposomes contained 1 mol% DOPE-pHrodo for visualisation. Scale bar: 50 μm. d CryoTEM images of SR-B filled, DOPC:4 liposomes before and after in situ irradiation (15 min, 370 ± 7 nm, 202 mW cm⁻²). Scale bars: 100 nm. e Maximum intensity projections of two-photon z-stacks (spanning the full width of the embryo) showing SR-B filled DOPC:4 liposome distribution, before and after UV irradiation. Scale bar: 50 μm. f Time-lapse images of SR-B filled DOPC: 4 → 3 liposome distribution during UV irradiation. Scale bar: 50 μm. g Mean SR-B fluorescence intensity within ROIs (lumen of the DA, orange line; DA vessel wall, green line, shown in e), before and during UV irradiation. SR-B fluorescence intensity in circulation decreases upon UV irradiation with a concomitant increase in SR-B fluorescence intensity associated with the DA blood vessel wall. Liposomes (e–g) containing encapsulated SR-B (10 mM) and otherwise unlabelled.