Figure 3.

Short-Term Effects of BFA on the Morphology of Golgi Stacks in BY-2 Cells.

Electron micrographs of Golgi stacks in high-pressure frozen/freeze-substituted BY-2 cells before (A) or early during ([B] to [F]) BFA treatment.

(A) Control. Typical appearance of a Golgi stack in untreated BY-2 cells. The stack has a clear cis-to-trans polarity indicated by the differences in membrane staining and cisternal morphology. Intercisternal elements (arrowhead) are seen only between trans-cisternae.

(B) BFA (5 min). This Golgi stack consists of only three cisternae that all have medial or trans appearance (cf. with [A]). Part of a clathrin coat still is present at one of the cisternae (arrow). The ER morphology is not altered at this time.

(C) BFA (10 min). Golgi (G) remnants that consist of only medial- and trans-like cisternae often are surrounded by accumulations of vesicles that appear to have originated at the trans-Golgi network. One of the stacks in this image has an ER cisterna associated with it (arrow).

(D) BFA (10 min). A clear example of an ER cisterna stacked onto a Golgi cisterna of medial/trans appearance (arrow).

(E) BFA (15 min). At this time, most cisternae resemble trans-cisternae and carry intercisternal filaments between them (arrowheads). Note the large number of Golgi-derived vesicles in the vicinity of the stack. The dilated membrane-bound compartment near the bottom appears to be ER because it has ribosomes associated with it.

(F) BFA (20 min). A single trans-like cisterna sandwiched between two ER cisternae (note the ribosomes on the outer membrane). Short patches of intercisternal filaments are present between the cisternae (arrowheads).