Fig. 1.

Expression of Wnt signaling pathway genes during zebrafish mesonephric kidney development and adult regeneration. (A-C) Whole-mount in situ hybridization showing the trunk kidney region of juvenile zebrafish at 35 days post fertilization (dpf). Juvenile zebrafish are rapidly growing and adding new nephrons. The transcription factor lhx1a is expressed in cell aggregates comprising newly forming nephrons (A), while the canonical Wnt receptor fzd9b (B) and canonical Wnt transcription factor lef1 (C) appear in similar aggregates, as well as in smaller clusters and single cells. (D-I) Whole-mount in situ hybridization showing the anterior trunk kidney region of adult zebrafish (between 6 months and 2 years). (D-F) Adult zebrafish are no longer actively forming new nephrons and only rarely express lhx1a, fzd9b or lef1 in aggregates. (G-I) In response to acute kidney injury by gentamicin injection, nephron formation is reinitiated by 7 days post-injury (dpi), and lhx1a, fzd9b and lef1 are strongly expressed in large aggregates and small clusters of cells. Representative images from n=12 (lhx1a), n=9 (fzd9b) and n=10 (lef1) juveniles, and n=3 (uninj lhx1a), n=13 (7 dpi lhx1a), n=3 (uninj fzd9b), n=5 (7 dpi fzd9b), n=3 (uninj lef1) and n=5 (7 dpi lef1) adult fish per condition from two independent experiments. Scale bars: 0.1 mm in A-C; 0.2 mm in D-I.