Figure 2.
DdNHE1 expression is developmentally regulated and is necessary for increased pHi in response to cAMP but is not necessary for developmentally regulated expression of cAR1 and Gα2. (A) Expression of the DdNHE1 transcript in Ax2 cells is induced after 6 h of starvation (left). DdNHE1 transcript is lost in a representative clone of Ddnhe1 − cells (right). (B) Ddnhe1 −cells identified by the presence of a 1-kb PCR product that is absent from Ax2 cells. Samples from three independently generated Ddnhe1 − clones are shown. (C) Expression of cAR1 and Gα2 is similar in Ax2 and Ddnhe1 − cells, as determined by Northern blot analysis. Expression of the ribosomal gene IG7 was used as a loading control. (D) pHi in the absence and presence of cAMP in chemotactically competent Ax2 (closed squares), Ddnhe1 − (open squares), and Ddnhe1 − /DdNHE1 (closed circles) cells was determined in cells loaded with the fluorescent pH-sensitive dye BCECF. Data are expressed as the mean ± SEM of three independent experiments.