V16 axiozoom

Brains of E18.5 embryos were removed and embedded in 7% low gelling temperature agarose in DMEM medium with 1% penicillin/streptomycin. Embedded brains were crudely sectioned at a thickness of ∼1–2 mm. Approximately 0.5 µl of DiI (Invitrogen) was injected into the cortical WM tracts at rostral and caudal axial levels and incubated for 8 h in Tyrode's solution. Tissues were then fixed overnight at 4°C in 4% paraformaldehyde before incubating for two weeks at room temperature in PBS with 1% penicillin/streptomycin. Images were captured using a Zeiss V16 Axiozoom fluorescent stereomicroscope equipped with an Axiocam 506 mono digital camera (Zeiss).

30 zebrafish larvae were randomly collected into an EP tube containing 1 mL dd H₂O and 30 μL 10 μg/mL AO staining solution was added to avoid light staining for 1 h. The fluorescence in the zebrafish larvae were observed and photographed immediately by using a pose fluorescence microscope (Zeiss V16 Axio Zoom, 546 nm filter).

Extracellular polysaccharide in the supernatant of R. solanacearum was determined quantitatively, in vitro growth of R. solanacearum strains were measured, and twitching motility examined as described by Ahmad et al. (2017) (link), except that twitching motility was visualized using a Zeiss AxioZoom v16 stereo zoom microscope (Carl Zeiss Microscope GmbH, Germany). Two replicates were used for each strain in the EPS assay and the experiment was repeated three times.