Figure 4

Mortality rate and distribution of P. caribaeorum ShK toxin-like peptide. (A) Fluorescent images of in vivo distribution of rhodamine B-conjugated peptide in Tg(fli1:EGFP)y1 zebrafish. Bright field pattern of zebrafish (6 dpf) treated with 20 μM of RhoB-PcShK3 (A-1) and free rhodamine B as negative control (A-2) for 24 h. Green fluorescence pattern of EGFP expression in transgenic Tg(fli1:EGFP)y1 zebrafish (B-3,B-4). Fluorescent images (A-5,A-6) from zebrafish (6 dpf) after incubation with rhodamine B-conjugated PcShK3 (20 μM) and free rhodamine B (20 μM) for 24 h. Merged images (A-7) of blood vessels (green) and rhodamine B conjugated PcShK3 (red). Merged fluorescent images (A-8) of blood vessels (green) and free rhodamine B (red); (B) Mortality rate of zebrafish larvae after exposure to peptide. The mortality rate reached 50% when zebrafish larvae was exposed to peptide (40 µM) for 8 h. The mortality rate reached 100% of zebrafish larvae exposed to peptide (75 µM) for 48 h. The LD₅₀ is estimated to 43.53 ± 6.45 µM.