Disruption of the Golgi apparatus and secretory mechanism in the desmid, Closterium acerosum by brefeldin A

The mucilage-secreting desmid, Closterium acerosum, issensitive to the secretory inhibiting drug, brefeldin A (BFA). After 5 minof treatment with 5 gml^-1 of BFA, the Golgi body displays the followingalterations: the number of cisternae decreases from 12-15 to 6-7;peripheries of cisternae from the same Golgi body often fuse to yieldunique profiles; secretory vesicles still merge from the Golgi body; thecisternal stack dissociates to form irregular masses in the alleys ofcytoplasm created by the lobes of the chloroplast. Fluoresbrite beadlabelling shows that mucilage production ceases in cells treated with BFAeven after only 5 min of treatment. Immunogold labelling usinganti-mucilage antibody reveals that mucilage production still occurs in theGolgi body and associated vesicles. Helix pomatialectin-gold labelling shows that wall synthesis still occurs in BFA-treatedGolgi bodies and wall precursors accumulate in the perforatecisternal/vesicular masses seen in the TGN region of the Golgistack.