Activity of putative matrix metalloproteinases 2 and 9 was detected with gelatin zymography. Ten ontogenetic and 10 regenerated zebrafish scales were cultured for 20 h in 100 μl MEMα (Invitrogen). Zymography was done according to Bildt and co-workers [48]. Relative MMP activity was calculated from band intensity with Quantity One software (Bio-Rad, Hercules, USA) and related to 2 ng human recombinant

Sunitinib price proMMP-2. GM6001 (ilomastat) from Millipore (Billerica, USA) was dissolved in DMSO at a concentration of 1 mg/ml. From two groups of six fish each, approximately 50 scales were removed from the left side of the fish. To specifically investigate MMP activity during scale plate remodelling, GM6001 exposure (100 nM) was started at day 2 in one group while the other group was exposed to the vehicle. Water was replaced every other day. On day 4 and day 7, three fish from each tank were sacrificed. Medium from overnight scale cultures was concentrated approximately fivefold by vacuum drying. Samples were loaded on a SDS-PAGE gel according to standard procedures. Proteins were transferred to an Immobilon-P PVDF membrane (Sigma-Aldrich) and used for Western blot with anti-MMP-9 (Anaspec) at a dilution of 1:1000. Biotinylated anti-rabbit IgG (Vector Laboratories, Burlingame, USA) was used as second antibody at a dilution of 1:1500. The Western

blot was developed with Vectastain ABC kit (Vector Laboratories) according to manufacturer’s instructions for staining with nickel-diaminobenzidine PR171 (Ni-DAB). Twenty scales (ontogenetic or 6 days regenerating) were taken from 6 fish and cultured overnight Vasopressin Receptor in 200 μl MEMα. Collected culture medium was mixed with 400 μl 100% ethanol and allowed to precipitate overnight. Samples were centrifuged 15 min at 1710 g and supernatants were collected. Pellets were washed with 200 μl 70% ethanol and supernatants

were added to previously obtained supernatants. Samples were dried in a hot stove and then resuspended in 50 μl 2 M NaOH. Samples were autoclaved for 30 min and hydroxyproline was measured according to the method described by Reddy and Enwemeka [49]. In ontogenetic (non-plucked) scales of adult male zebrafish, mmp-9 expression was confined to cells on the episquamal side, along the radii and margins of the scale (see Figs. 1A, B, and D for whole-mounts and Figs. 1C and E for histological sections). Scleroblasts on the hyposquamal side showed no hybridisation; the mmp-9-positive cell population was confined mainly to the episquamal surface of the scale and included both mononucleated cells ( Figs. 1C and D) and multinucleated cells ( Figs. 1B and E). Fig. 1F shows a superimposed confocal image of plasma membranes stained with concanavalin A FITC conjugate. No separate plasma membranes were seen dividing the cytoplasmic mass of cells similar to the mmp-9 expressing cell in Fig. 1B.