il1b knockdown or Dex treatment rescued the clo from apoptosis.
(A) Simultaneous detection of apoptosis by TdT-mediated dUTP nick end labeling (TUNEL) and the il1b-expressing cell at 12 hpa in the clo mutant carrying the transgene il1b:egfp. Most of the TUNEL-positive cells were detected in close association with the il1b-expressing epithelial cells. Vertical and horizontal lines indicate the approximate sites of the optical sections. Scale bar, 100 μm. (B) RT-PCR analysis of il1b and actinb1 expression in zebrafish larvae injected with il1b MO. The il1b MO was targeted to the splice donor site. Arrowhead indicates the aberrant transcript. (C) TUNEL analysis in amputated WT or clo larvae (12 hpa) after il1b knockdown. Injection of il1b MO substantially reduced the apoptosis of regenerative cells in the clo mutant, whereas the apoptosis was unaffected by std MO. Scale bars, 50 μm. (D) Quantification of TUNEL staining in the areas bracketed in (C). (E) ISH analysis of il1b expression at 3 hpa in larvae treated with Dex. DMSO: dimethyl sulfoxide, used as the vehicle. Dex treatment abolished il1b expression. Scale bar, 50 μm. (F) TUNEL staining in the amputated fin fold at 12 hpa in Dex-treated WT and clo larvae. Scale bars, 50 μm. (G) Quantification of TUNEL staining in the areas bracketed in (F). In (D) and (G), data are presented as means ± SEM. Student’s t test, **p<0.01; ***p<0.001; N.S., not significant (p=0.172).