Figure 7.

PI-permeable feeder cells underlie the sporulation layer in colonies and colocalize in colonies with active Rlm1. (A) Sections of 4-day colonies containing the ime2Δ-GFP allele (SH5071) overlaid with agar containing PI (see Materials and Methods): (top) GFP, (middle) PI, and (bottom) overlay. (B) Six-day colonies as in A resuspended in PI/sorbitol and visualized by bright-field microscopy (top left), red fluorescence microscopy (top right), green fluorescence microscopy (bottom left), and merge of green and red images (bottom right). (C) Six-day spot colonies containing the UAS_Rlm-lacZ allele (SH5065) were overlaid with agar containing 120 μg/ml X-gal and 0.1% SDS and incubated for 2 days; then they were resuspended as in B and visualized by bright-field (left) and fluorescent microscopy (right). Arrows indicate representative cells that are both blue and red. (D) Quantification of cell populations in B and C. (Left) Cells as in B that fluoresce only red (R), only green (G), or both colors (R + G) (n = 4). (Right) Cells as in C, except that incubation after overlay was only 1 day, staining only red (R), only blue (B), or both colors (R + B) (n = 3).