Figure 1.
Gene expression of sodium (potassium) chloride (nkcc/ncc) cotransporters.
Expression levels of nkcc1a (a), nkcc1b (b), nkcc2 (c), ncc (d), in the gills and EGI tract of tilapia acclimated to freshwater (FW), seawater (SW) and hypersaline water (HSW). Each histogram bar represents the mean ± s.d. of the expression levels (log10 copies of transcript per 50 ng cDNA). Expression levels labeled with different lowercase alphabets are significantly different (one-way ANOVA followed by Duncan's post-hoc test; P<0.05) within the same tissue.
Figure 2.
Gene expression of cystic fibrosis transmembrane conductance regulator (cftr) and sodium potassium ATPases (nka).
Expression levels of cftr (a), nka-α1 (b), nka-α3 (c) in gills and EGI tract of tilapia acclimated to freshwater (FW), seawater (SW) and hypersaline water (HSW). Each histogram bar represents the mean ± s.d. of the expression levels (log10 copies of transcript per 50 ng cDNA). Expression levels labeled with different lowercase alphabets are significantly different (one-way ANOVA followed by Duncan's post-hoc test; P<0.05) within the same tissue.
Figure 3.
Gene expression profiles in gills and gastro-intestinal tract of tilapia acclimated different salinities.
Heatmap representing quantity (log10 copies per 50 ng cDNA) of nkcc1a, nkcc1b, nkcc2, ncc, cftr, nka-α1, and nka-α3 in the gills and EGI tract segments, including the esophagus, stomach, anterior intestine (AI), middle intestine (MI), and posterior intestine (IG) of tilapia acclimated freshwater (FW), seawater (SW) and hypersaline water (HSW). Different alphabets indicates significant (P<0.05) differential gene expression between the salinity conditions (refer to text for the scoring system) within a tissue.
Figure 4.
Immunohistochemical localization of transporters in gills of tilapia acclimated to different salinities.
Representative micrographs of immunohistolocalization of Nka (green) with either Nkcc/Ncc (a–c; red) or Cftr (d–f; red) in the gills of tilapia acclimated to FW (a,d), SW (b,e) or HSW (c,f). Co-localization of red and green fluorochromes results in yellow-orange staining. Higher magnification (10×) of boxed areas in (a–f) correspond to panels (a′–f′). Sections are counter stained with the nuclear stain DAPI and overlaid with the DIC image for tissue orientation. Arrows indicate apical staining and arrowheads tubular system (basolateral) staining. Scale bar 100 µm (a–f), 10 µm (a′–c′).
Figure 5.
Immunohistochemical localization of transporters in anterior and posterior intestine of tilapia acclimated to different salinities.
Representative micrographs of immunolocalization of Nka (green) with Nkcc/Ncc (red) (a–d, f–h) from FW (a, f), SW (b, g) and HSW (c, h) acclimated tilapia. (d) A representative higher magnification micrograph of Nkcc/Ncc staining of the brush border of enterocytes with basolateral Nka staining from the anterior intestine of SW-acclimated fish. (e) Apical Cftr (red) double labeling with Nka (green) in the anterior intestine of a FW-acclimated fish. Panels (a–e) are sections of anterior intestine (AI) while panels (f–h) are sections of posterior intestine (PI). Sections are counter stained with the nuclear stain DAPI and overlaid with the DIC image for tissue orientation. Scale bar 100 µm (a–c, f–h); 25 µm (d,e).
Table 1.
Normalized luminosity indices of Nkcc/Ncc and Nka immunostaining in the gills, anterior intestine (AI) and posterior intestine (PI) of Mozambique tilapia.