Figure 2

Expression of V-type H⁺ ATPase protein on the apical membrane of posterior rectal cells and P-type Na⁺/K⁺ ATPase protein expressed on basolateral membrane of anterior rectal cells of A. taeniorhynchus larvae. (A) Whole mount of the two-part rectum from larval A. taeniorhynchus acclimated to 100% seawater showing immunolocalization of V-type H⁺ ATPase protein (blue) to the posterior rectum (PR) and P-type Na⁺/K⁺ ATPase protein (red) to the anterior rectum (AR). (B) Sectional preparation of segmented rectum from a larva acclimated to 100% seawater indicating expression of the V-type H⁺ ATPase protein (dark grey staining, indicated by black arrows), on the apical membrane of PR facing the rectal lumen. P-type Na⁺/K⁺ ATPase protein (red staining, indicated by red arrows) was localized to the basolateral membrane of the AR that would face the hemocoele. Scale bars, 100 μm (A) and 25 μm (B).