Airyscan confocal system

Embryos were fixed in 4% PFA and exposed to CellMask™, which stains membranes non-specifically, then imaged by epifluorescence on an inverted LSM710 or LSM880 with Airyscan confocal system (Zeiss). For neural plate morphology, images were re-sliced in Fiji to obtain transverse sections of the Closure 1 region, located at the level of the 3rd somite. The distance between neural folds was measured at ten sequential positions, 20 µm apart, moving rostrocaudally along the Closure 1 region (200 µm in total). For somite morphology, the images were re-sliced in Fiji (from dorsal to ventral surface) to obtain longitudinal sections through the somites. Length (rostrocaudal orientation) and width (mediolateral orientation) measurements were taken half way through the somite at the level of the 3rd/4th somite. Two somite pairs (4 individual somites) were measured per embryo.

The cellular FRAP experiments were performed using the Zeiss Airyscan Confocal system (Zeiss, Germany). Three laser lines of the Argon laser (458, 488, 514 nm) were used to bleach the GFP signals in the areas of interest at 100% transmission and 10 iterations. The bleach was started after one acquisition scan, and the images were acquired at the indicated intervals.