Fig. 1

Damage of kidney by nephrotoxic gentamicin induces tubular regeneration and neonephrogenesis in N. furzeri. a Comparison of kidney anatomy of zebrafish and b N. furzeri after preparation and c, d after injection of fluorescent dextran-FITC, which is reabsorbed in the proximal parts of the tubule. Scale bar: 1 mm e Transverse section of N. furzeri kidney, stained with h and e. Different compartments of the nephron are indicated. Brush border, BB, of proximal tubule is shown in higher magnification. Abbreviations: G, glomerulus; PT, proximal tubule; DT, distal tubule; H, hematopoietic tissue. Scale bar: 50 μm. f After gentamicin application fish were injected with dextran-FITC 24 h prior to preparation every second day, to obtain information about recovery of kidney functionality after damage. g TUNEL-assay was performed to study apoptotic processes in kidneys after damage. Red color labels apoptotic cells, nuclei are labeled with DAPI in blue. h Fish were injected with EdU 2 h prior to being sacrificed. Encircled areas mark tubules in kidney of fish. Red staining shows incorporation of EdU into DNA, DAPI counterstaining is seen in blue. i H and E staining of kidneys after injection of PBS or gentamicin, white arrows label damaged tubules, black arrows indicate newly developing nephrons. Inset shows a tubule with an intact brush border. Scale bar g, h, i: 20 μm. Kidney function j, apoptotic cells k and proliferation l was quantified. To assess kidney function, all kidneys being positive for dextran-FITC were counted and related to all kidneys, n = 15 fish/time point. For quantification of apoptosis and proliferation, red labeled cells in tubules were counted and related to total number of tubules, n = 3–4 fish/time point