Figure 2: Reorganization of the ER upon TRI production.

(a–e) Reporter strains Hmr1-GFP (a), GFP-HDEL (b), Sec22-GFP (c) as well as the wild type PH-1 (d and e) were grown in MM (left panels) or TIM (right panels). (a) Fluorescence of Hmr1-GFP and ER-Tracker co-localize at reticulate peripheral ER (red arrow) and circular perinuclear ER (red arrowhead) in MM, and at ovoid structures (white arrow) and crescent structures (white arrowhead) upon TRI induction. Smaller circular structures (unfilled white arrowhead) stained with ER-Tracker, do not co-localize with Hmr1-GFP and were identified as lipid bodies (see d). (b and c) Similar differences in ER pattern in MM or TIM are observed with GFP-HDEL (b), Sec22-GFP (c) and with the wild type PH-1 stained with ER-Tracker (d). (d) Dual staining of PH-1 with ER-Tracker and BODIPY shows that lipid bodies (unfilled arrowheads) co-localize with ER-Tracker in MM and TIM. (e) Super resolution microscopy of the ER of PH-1 stained with ER-Tracker (yellow) in MM or TIM. Single images from z-stacks of the ER (row 1) and 3D reconstruction (row 2 x/y view, and 3 y/z view; Supplementary Movies S1, S2) demonstrate the reticulate pattern of the perinuclear ER (red arrowhead) and peripheral ER (red arrow) in MM and the thickened perinuclear ER (white arrowhead) and peripheral ER (white arrow) in TIM in detail. The focal x/y view of a z-stack image shows a fine network of ER tubules and vesicular structures. This fine network (asterisk) seems to be connected to other parts of the ER as well as to lipid bodies (unfilled arrowheads).