Fig. 5.

Temporal expression of PtAP-1 in the gill after low-salinity challenge at 0, 3, 9, 12, 24, 36, and 48 h. PtAP-1 mRNA level was normalized against the control group, with β-actin used as the internal control in order to calibrate cDNA-template levels for all samples. Each bar represents the mean ± standard error (n = 5 individuals). Data for the same challenge time point with different letters indicate significant differences (P < 0.05) among different time points or groups