Caulobacter cultures (strain Snc04) induced for 1 hour at 30 degrees C, labeled in M2G medium for 2 hours at 30 degrees C (in the presence of 1.8 micromolar ReAsH-EDT2) and photoconverted. Samples were fixed with 2.5% glutaraldehyde with 1% acrolein in 0.05M sodium cacodylate pH 7.4 with 3 mM CaCl2 and 1 % sucrose followed by conventional osmium tetroxide/potassium ferrocyanide post-fixation, dehydration and embedding. Film images were acquired using a JEOL 4000, at a magnification of 30,000X.