Fig. 3.

dfsAC is present in the gill, and cAMP-producing activity in the gill matches recombinant dfsAC. (A) Adenylyl cyclase activity in gill homogenates measured in the presence 50 mM NaCl or NaHCO₃ in the presence or absence of 50 μM KH7. Shown are the averages of quadruple determinations with SEM. Equivalent results were obtained with 4CE. Lowercase letters denote levels of activity that are not significantly different from each other by repeated-measures two-way ANOVA (P < 0.05 for treatment, time, and interaction), Bonferroni’s posttest. (B) KH7-sensitive cAMP activity in gill homogenates measured as indicated in A. EC₅₀ = 2.9 mM NaHCO₃. (C) Western blot of dogfish shark gill homogenate (crude) and high-speed supernatant (sup) using anti-dfsAC in the absence or presence of immunizing peptide. (D) Immunofluorescence using anti-dfsAC (green) in dogfish gill. Nuclei were labeled with DAPI (blue). (E) Staining using anti-dfsAC antisera preabsorbed with excess immunizing peptide; similar results were obtained with preimmune serum. (F and G) Higher magnification pictures of dfsAC immunolabeling. (G) Immunolabeling in pillar cells. (Scale bars = 10 μm.)