Fig. 6

Reduction of shrub activity causes moderate enlargement of MVBs. (A–D) Ultra-structural analysis of shrub mutant cells partially rescued by BAC^shrub-CHMP4B (shrub^4-1; BAC^shrub-CHMP4B/+). Representative TEM pictures of MVBs of wild-type (A) and partially rescued shrub mutant (B) wing disc cells. (B”) Colourized overlay of estimated ILV area (50.6% of total MVB area) with the original EM image of the MVB shown in (B’). The area that is not considered as ILV content/electron-dense material within the MVB is highlighted in bright red. (C) Statistical analysis of the MVBs of wild-type (blue) and partially rescued shrub mutant (red) cells. The average area of MVBs in shrub mutant cells is significantly increased. (D) Quantification of electron-dense material per area within the lumen of wt (blue) and partially rescued (red) MVBs to measure ILV formation (as shown in B’). There is no change in the ILV content in the partially rescued shrub mutant cells in comparison to wild-type [(C, D) wt n = 337 MVBs; (C) shrub^4-1; BAC^shrub-CHMP4B/+ n = 271; (D) shrub^4-1; BAC^shrub-CHMP4B/+ n = 263; (C) Mann-Whitney test, two-tailed p < 0.0001 (****). (C) Values greater than 0.5 μm² are not shown (wt, 1 out 337 MVBs; shrub^4-1; BAC^shrub-CHMP4B/+, 10 out of 271 MVBs). (D) Unpaired t test, p < 0.05 (*) (box plot: whiskers: 5–95 percentile; mean shown as “+”)]. Scale bar (A, B, B’) 250 nm