Fig. 5. Changes in the levels of mRNA encoding NKCC1a, NCC, NHE3 and the H⁺-ATPase A-subunit following transfer of Mozambique tilapia embryos from (A) freshwater to seawater and (B) vice versa, quantified using real-time PCR. Each value represents the mean ± s.e.m., N=7. The data from both transfer experiments (which were conducted simultaneously and assays run at the same time) were normalized to the highest value for each gene (NKCC1a, at 6h of freshwater-to-seawater transfer; NCC, at 72h of seawater-to-freshwater transfer; NHE3, at 24h of seawater-to-freshwater transfer; H⁺-ATPase, at 72h of freshwater-to-seawater transfer), which were assigned an arbitrary value of 1. The data at 0h were derived from the same samples as used in Fig. 4. Unfilled circles, values in freshwater; filled circles, values in seawater. Values with different lowercase letters are significantly different (e.g. a significant difference is observed between `a' and `b', but not between `a' and `a,b', or between `b' and `a,b'; P<0.0125, Tukey–Kramer test).