Fig. 6. Acidocalcisomes from ap3 promastigotes contain a soluble pyrophosphatase, but are devoid of electron-dense material. (A) Western blot analysis of whole-cell lysates from L. major promastigotes with the anti-VSP1 antibody. EF1- was used as a loading control. Molecular masses are indicated on the left. (B) Immunofluorescence analysis of L. major promastigotes using anti-VSP1 antibody. The corresponding DIC images are shown. (C, left panels) electron spectroscopic whole cell imaging of WT, ap3 and ap3::P_RRNA AP3 promastigotes showing presence or absence of electron-dense polyphosphate in acidocalcisomes (arrowheads). (Right panels) Corresponding transmission electron microscopy of sections of these cell types. Acidocalcisomes are indicated with arrowheads. Nuclei (n) and glycosomes (arrows) are indicated as other organelles for reference; k, kinetoplast. Scale bars, 10 µm (B) and 2.0 µm (C).