Fig. 9. (A,B) Immunofluorescence of mouse anti-human Na+/K+/2Cl– cotransporter (NKCC) and goat anti-mouse IgG Oregon Green 488 in seawater-adapted killifish posterior intestine shows the distribution of Na+/K+/2Cl– cotransporter (green fluorescence) in an intestinal villus. (A) In approximately 20 % of sections, NKCC immunofluorescence is evenly distributed throughout the enterocyte cytoplasm but is absent from the brush border and nuclei (white arrow) and from goblet cells (asterisk). In some cells, NKCC immunofluorescence is seen in the brush border (broad yellow arrow). (B) Same section, bright field overlaid with green fluorescence. (C) NKCC immunofluorescence in most sections (approximately 80 %) is present in the cytoplasm and in the brush border (yellow arrow) and is absent from nuclei (white arrow) and goblet cells (asterisk). (D) Same section but with bright field overlaid with green fluorescence. (E,F) Immunofluorescence of mouse anti-chicken Na+/K+-ATPase and goat anti-mouse IgG Oregon Green 488 in seawater-adapted killifish posterior intestine showing the distribution of Na+/K+-ATPase (green fluorescence) in an intestinal villus. (E) Na+/K+-ATPase immunofluorescence is distributed throughout the basal two-thirds of the enterocytes but not in the nuclei (white arrow), the goblet cells (asterisk) or the brush border, which stains (non-specifically) with Mitotracker Red. (F) Na+/K+-ATPase immunofluorescence overlaid with bright field. Scale bars, 20 µm.
