Figure 4

Gene expression pattern and functional characterization of teleost Aqp1b. (A-D) Representative RT-PCR analysis of aqp1b (upper panels) and bactin (lower panels) transcripts in sea bream (A), European eel (B), Senegalese sole (C) and zebrafish (D) tissues. PCR products were detected by Southern blot. Minus indicates absence of RT during cDNA synthesis. The size (kb) of PCR products and molecular markers are indicated on the left and right, respectively. (E) P_f and Hg²⁺ inhibition of X. laevis oocytes expressing teleost Aqp1a or Aqp1b. Oocytes were injected with cRNAs encoding sea bream Aqp1a or Aqp1b (1 ng), eel Aqp1b (10 ng), Senegalese sole Aqp1b (10 ng) or zebrafish Aqp1b (10 ng), or with 50 nl of water (control). The P_f was assayed in the presence or absence of 0.7 mM HgCl₂. Some oocytes treated with HgCl₂ were incubated with 5 mM β-mercaptoethanol (βME) for 15 min before swelling measurements. Values represent the mean ± SEM (n = 6–10 oocytes) from a representative experiment.