Fig. 5. Tissue distribution of eel AQP1 (S-AQP and L-AQP) mRNA determined by northern hybridization in freshwater (FW)- and seawater (SW)-adapted eels. Hybridization signals were detected as a single band of approximately 1.3 kb (arrows) in the heart, intestine, spleen and swim bladder, but not in the other tissues examined.