Figure 4. The exocyst regulates alae formation independently of RAL-1. (A) Quantitative electron microscopy analysis reveals that the MVB density issimilar in
sec-5(
pk2358) and
sec-8(
ok2187) null mutants and WT controls. MVB density is increased after
sec-8(RNAi) but not
sec-15(RNAi) comparedwith control(RNAi) (P values, Mann-Whitney test). (B) Example of an MVB attached to the apical plasma membrane in
sec-5(
pk2358) (enlarged in B').(C) Small vesicles (<100 nm diameter; black arrows) accumulating under the plasma membrane in
sec-8(
ok2187) mutants. (D and E) The exocyst subunitsSEC-8 (D) and SEC-15 (E) do not colocalize with VHA-5 in the epidermis. The scale bars in D apply to E. APM, apical plasma membrane; Cu, cuticle; Cy,cytoplasm; MVBm, MVB outer membrane