Cell death in the adult zebrafish SAG upon lesion. (A) Antibody staining of the adult zebrafish SAG labeling ubiq:secAnnexinV-mVenus-positive cells and HuC/D-positive neurons. In contrast to unlesioned sides (ULS), a strong ubiq:secAnnexinV-mVenus-signal was present in the SAG following sham treatment or NaCl and Ouabain injections at 12 h post lesion (hpl). In the medial part of the SAG, which harbors the neurogenic niche and the neuronal cell bodies, only very few HuC/D-positive cells showed a weak ubiq:secAnnexinV-mVenus staining in all samples (arrows in b and f). In the distal part of the SAG, where the neurites of the sensory neurons innervate the sensory patch, a strong ubiq:secAnnexinV-mVenus staining was observed in sham-treated as well as NaCl- and ouabain-injected SAGs, but almost no signal was detected in unlesioned control sides (arrowheads in c, e, and g). Magenta dotted line and asterisk in ouabain-injected SAG indicates a massive hemorrhage in this injected site. (B) Colabeling of mVenus with calretinin revealed the presence of ubiq:secAnnexinV-mVenus in neurites (arrowhead in c) of sham-treated SAGs but not in unlesioned control sides. (C) Antibody staining labeling neurons (elavl3:GFP and calretinin) combined with TUNEL assay. TUNEL assay revealed presence of apoptotic neurons in the SAG of adult elavl3:GFP zebrafish in all three lesion types at 12 hpl, whereas no TUNEL-positive neurons were found in the unlesioned control side. Scale bars: (A) 200 μm; (B): 50 µm.
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