Western blot analysis of zebrafish embryo lysates shows that BCNSia is present in sialoglycoproteins. A) Structure of affinity probe 5 used in Western blot experiments. B) Western blot of lysates. Embryos were injected with BCNSia or vehicle, grown to 48 hpf, deyolked, and lysed. The resulting lysates were treated with sialidase followed by 5 and then analyzed by Western blot with an anti-dinitrophenyl horse-radish peroxidase conjugate. AU = Arthrobacter ureafaciens, DNP = dinitrophenyl, VC = Vibrio cholerae.