Poster: Protein Targeting & Vesicular Trafficking

Abs # 1191: Assembly of the Golgi apparatus and the role of microtubules

Presenter:	Owen, T. Page , tpowe@conncoll.edu
Authors	Owen, T. Page  (A)   Fahey, Laura M (A)   Grigg, Sage E (A)
Affiliations:	(A): Connecticut College

When cultured tracheary elements from Zinnia elegans mesophyll cells are treated the inhibitor brefeldin A during early secondary cell wall biosynthesis, the Golgi apparatus dissipates into the cytoplasm while the ER remains intact. Concurrently, the arrested cell wall development becomes a useful marker for Golgi activity. We treated differentiating tracheary elements with brefeldin A for 2 hours, washed the cells with fresh culture media, then fixed the cells for electron microscopy over time (10 to 120 min). Early during recovery, cells had cisterna with numerous small vesicles apparently fusing to each other on both sides of the Golgi. By 50 min, two Golgi stacks with outlying rows of punctuated membrane surrounded the assembly; by 60 min, the cells typically had 3 well-formed cisternae. Clathrin-coated vesicles commonly appeared during reassembly but not in close contact to the Golgi. After 2 h the Golgi were fully formed and secondary cell wall thickenings became more apparent by fluorescent staining. An early developmental step of tracheary element differentiation is the realignment of the microtubule cytoskeleton. We are currently examining microtubules stabilized with paclitaxel to prevent their restructuring, and then examining post-brefeldin-treated and washed cells for perturbations in Golgi reassembly. Supported by the Keck Undergraduate Science Program.